Table of Content

16 September 2016, Volume 49 Issue 18

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CROP GENETICS & BREEDING·GERMPLASM RESOURCES·MOLECULAR GENETICS

Progresses in Research on Cotton High Yield Breeding in China

YU Shu-xun, FAN Shu-li, WANG Han-tao, WEI Heng-ling, PANG Chao-you

Scientia Agricultura Sinica. 2016, 49(18):  3465-3476.  doi:10.3864/j.issn.0578-1752.2016.18.001

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Cotton is an important economic crop in China, the stable development of cotton production is concerned with the interests of 20 million of farmers. Yield is the most important trait on the premise of the comprehensive development of other traits, so high yield is the most important goal of cotton planting. From 1950 to 2015, the cotton yield per unit area in China was increased by more than 9 times, and the introduction and improvement of varieties have made a great contribution to the increase of cotton yield. In recent years, the improvement of cotton yield per unit area was slow because of the narrow genetic diversity, hindering seriously the development of cotton industry. Cotton yield per unit area contains four major components, stock number per unit area, boll number per plant, single boll weight and lint percentage. This paper analyzed the roles of four components in cotton planting. Boll number per plant and lint percentage are more important for the cotton yield breeding, but the improvement of cotton yield is a complex progress which need every trait coordinated properly. At the same time, this paper discussed the important ways and its research progress to be used for high-yield breeding. Germplasm introduction has played an important role in raising cotton yield and replaced the Gossypium arboreum varieties of lower productivity and poor quality in China, and promoting the development of cotton breeding in China. Some significant varieties were cultivated by conventional breeding, for example, early maturing cotton CCRI 16, high-yielding cotton variety Lumian1, high-yielding and disease-resistant variety CCRI 12 etc. These varieties promoted the development of cotton industry in China, and which were the important parents of cotton breeding. The utilization of heterosis is an effective approach to cotton breeding of high yield and good quality. Lots of significant hybrids were cultivated by cross breeding. For example, the planting area of CCRI 29 once accounted for 50% of hybrid cotton in Yangtze River basin of China. And the research of male sterility line plays a key role for sustainable development of heterosis utilization. The development of molecular marker technology provides technical supports for molecular breeding of cotton, and multiple stable QTL related with yield trait has laid a foundation for molecular mark assisted breeding. The development of transgenic technology provides an opportunity for cotton molecular design breeding. The discovered genes related with yield trait are few, so more work should be done on the excavation of new genes. At present, the cotton yield per unit area in China is at the international leading level. Because China has more people and less land, the increase of cotton yield per unit area is a way out for cotton industry based on the premise that not to reclaim land under food crops. So the following suggestions were put forward: It is necessary to collect plant resources and pay more attention to the innovation of germplasm resources; the cytoplasmic male sterility (CMS) research should be strengthened, the seed production technology and cost should be simplified and promoting the potential of hybrid breeding; exploring the high yield related genes using high-throughput sequencing technologies in whole genome for molecular marker assisted breeding and genome-wide selective breeding; it is significant to cultivate new varieties with high-yield, good quality, early-maturing and suitable for mechanization planting with pyramiding breeding.

Development of Wheat -Thinopyrum elongatum Translocation Lines Resistant to Fusarium Head Blight

ZHANG Lu-lu, CHEN Shi-qiang, LI Hai-feng, LIU Hui-ping, DAI Yi, GAO Yong, CHEN Jian-min

Scientia Agricultura Sinica. 2016, 49(18):  3477-3488.  doi:10.3864/j.issn.0578-1752.2016.18.002

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【Objective】The objective of this study was to transfer the chromosome 7E of Thinopyrum elongatum into cultivated common wheat (Triticum aestivam L.) to develop translocation lines resistant to Fusarium Head Blight (FHB) and thereby to provide new germplasm for improving FHB resistance in common wheat.【Method】The F₂ seeds from the cross between Yangmai16 and DS7E(7B) were radiated using ⁶⁰Co (at 30 000 rad), DS7E(7B) being a substitution line in which the chromosome 7B of Chinese Spring common wheat was substituted with the chromosome 7E of Th. elongatum. The survived M₁ plants were harvested, after visual selection for agronomic traits. The M₂ to M₄ populations were selected for agronomic traits, FHB resistance under single drop injection with Fusarium graminearum, and molecular markers specific to the chromosome and chromosomal arm of 7E for Th. elongatum, followed by cytological confirmation for the presence of 7E chromosomes using Th. elongatum genomic DNA as probe by genomic in situ hybridization (GISH). 【Result】Thirteen M₁ plants with varying degrees of FHB resistance were selected, and the corresponding M₂ plants were examined for the presence of previously developed molecular markers specific to chromosome 7E . Seven plants were found to carry the long arm of 7E and 14 were found to carry the short arm of 7E. After selfing, 13 plants carrying markers specific to the long arm of 7E chromosome and 3 plants carrying markers specific to the short arm of 7E chromosome were identified out of 223 M₃ plants. GISH analysis was conducted for the progenies (M₄) derived from 12 M₃ plants and it was found that the progenies from nine of the M₃ lines were wheat-Th. elongatum translocation lines (2n=42), and those from two other M₃ plants were chromosome addition lines with the short arm of 7E (2n=44). Continued selection led to the development of three translocation lines carrying the long arm of 7E, which were named as TW-7EL1, TW-7EL2 and TW-7EL3, respectively. A fourth line was a chromosome addition line with the short arm of 7E and was named as W-DA7ES. These four lines were derived from two different M₁ plants. Evaluation of FHB resistance indicated that the translation lines were similar to Sumai 3 in FHB resistance, better than Chinese Spring and Yangmai 16, while the addition line was considerably poorer in FHB resistance.【Conclusion】Translocation lines with chromosome 7EL that are resistant to FHB were developed effectively and accurately by joint use of phenotypic selection, screening for chromosome-specific molecular markers to 7E, and genomic in situ hybridization. The chromosome 7EL of Th.elongatum carries FHB-resistant genes. 

QTL Analysis of Heading Date and Yield Traits in Japonica Rice Under Cold Water Stress in Different Years

YANG Luo-miao, SUN Jian, ZHAO Hong-wei, WANG Jing-guo, LIU Hua-long, ZOU De-tang

Scientia Agricultura Sinica. 2016, 49(18):  3489-3503.  doi:10.3864/j.issn.0578-1752.2016.18.003

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【Objective】Heading date, seed setting rate, thousand grain weight and grain weight per plant are traits associated with yield and these traits are greatly influenced by cold water. Therefore, the QTL analysis of heading date, seed setting rate, thousand grain weight and grain weight per plant of rice under cold water stress were conducted in the present study in order to provide a scientific basis for the rice genetic mechanism of cold tolerance and molecular marker assisted breeding. 【Method】 Totally 190 recombinant inbred line (RIL) populations derived from two rice varieties (Dongnong 422 and Kongyu131) were used as materials under cold water irrigation at booting stage, a linkage map was constructed using 155 SSR markers. The correlation analysis on the initial heading (IHD) date, full heading (FHD) date, seed setting rate, thousand grain weight and grain weight per plant were conducted to detect (QTL) these traits by stepwise joint QTL mapping method. The correlations between QTLs of different traits were determined by using the hypergeometric probability function. 【Result】 IHD and FHD were postponed under cold water irrigation in two parents and RIL. Seed setting rate, thousand grain weight and grain weight per plant had significant changes. Those traits had a positive or a negative correlation. A total of 71 QTLs were detected by using stepwise joint QTL mapping method, among them, 37 QTL were associated with cold tolerance, among them, 28 were detected under single- environment, 11 QTL explained beyond 10% of phenotypic variance, 10 QTL were detected under the single-treatment, 6 QTL explained beyond 10% of phenotypic variance, all 17 QTL were associated with cold tolerance. Five QTL had significant QE interaction under the Joint QTLs combining data of all environments. Twenty pairs of additive×additive epistasis were detected, and two main-effect QTL had epistatic interaction. Hypergeometric probability function showed that QTL was associated among those traits. By comparing the mapping results, some of the detected QTLs were in the same or adjacent chromosomal regions of previously reported QTLs, which include qIHD7-2, qFHD7-2, qFHD7-1 and qIHD7-1. These four QTL were stable in different environments, meanwhile, qIHD7-1, qIHD7-2, qFHD7-1, qSSR7-1 and qSSR7-2 were associated with cold tolerance. These QTL loci may provide a basis for molecular breeding for cold resistance in rice.【Conclusion】Seed setting rate has similar genetic mechanism with heading date, thousand grain weight and grain weight per plant under cold water stress. However, heading date, thousand grain weight and grain weight per plant are independently inherited. Meanwhile, it is more harder to breed the rice has high seed setting rate than heading date, thousand grain weight and grain weight per plant under cold water stress.

TILLAGE & CULTIVATION·PHYSIOLOGY & BIOCHEMISTRY

Guidance: Nitrogen Management with High Yield and High Efficiency for Oilseed Rape in China

LU Jian-wei

Scientia Agricultura Sinica. 2016, 49(18):  3504-3505.  doi:10.3864/j.issn.0578-1752.2016.18.004

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Integrated Nitrogen Management Strategy for Winter Oilseed Rape (Brassica napus L.) in China

REN Tao, LU Jian-wei

Scientia Agricultura Sinica. 2016, 49(18):  3506-3521.  doi:10.3864/j.issn.0578-1752.2016.18.005

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Oilseed rape is one of the predominant oil crops in China. Yangtze River Basin is the key winter oilseed rape production region in China, where the specific climatic conditions, soils and cultivation practices induce the different characteristics of soil nutrient supply, crop growth and nutrient demand. High crop yield, high economic benefit and high nutrient use efficiency are the determinants of agricultural production and sustainable development. Asynchrony between oilseed rape nitrogen (N) demand and soil N supply in space and time is the major reason that excessive N or deficient N input is the most important limiting factor of rapeseed yield and economic benefit. Optimal N fertilization is critical to achieve high seed yield and high N fertilizer use efficiency. In this paper, the authors reviewed the recent perspectives on oilseed rape N management, including crop N uptake, soil N supply, the critical N fertilizer application methods and the matching techniques. Further, considering the characteristics of crop growth and soil N supply, an integrated N management strategy, of which the key is “promotion in early and stabilization in late” to match crop N uptake and soil N supply, is put forward. The core content of the strategy includes (1) adjusting the timing and proportion of N fertilization and N sources to satisfy N requirement in the seedling period, focusing on soil N supply to promote N transfer and re-utilization since stem elongation period; (2) Depending on soil N supply under different rotations and/or crop straw incorporation, coordinating the distribution of N fertilizer in whole growing season; (3) Synergistic interaction with other practices including optimal plant density, fertigation, application with other nutrients and mechanization to obtain high seed yield and high N fertilizer use efficiency.

Effects of Nitrogen and Planting Density on Accumulation, Translocation and Utilization Efficiency of Carbon and Nitrogen in Transplanting Rapeseed with Blanket Seedling

Scientia Agricultura Sinica. 2016, 49(18):  3522-3531.  doi:10.3864/j.issn.0578-1752.2016.18.006

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【Objective】 In order to discuss the relationship between carbon (C) and nitrogen (N) metabolism and yield in transplanting rapeseed with blanket seedling, the effects of different N application rates and planting densities on accumulation, translocation and utilization efficiency of carbon and nitrogen were studied. 【Method】 In this study, Ningza 1818 was planted by artificial transplanting with blanket seedling. The differences of C and N accumulation and translocation rates before and after flowering period, carbon utilization efficiency for grain production (CUEg) and nitrogen utilization efficiency for grain production (NUEg) under different years, nitrogen application rates and densities were studied. 【Result】The results showed that transplanting rapeseed with blanket seedling could obtain high yield (3 750 kg·hm^-2) under suitable conditions. The yield increased significantly with increased densities under 0 and 225 kg·hm^-2 N rates. There was no significant difference among 1 plant per spot, 2 plants per spot and 3 plants per spot with 125 000 spots/hm² transplanting density under 300 kg·hm^-2 N rate. The ability of C accumulation was significantly higher than that of N accumulation in rapeseed. The average C/N ratio before and after the early flowering period was 16.30 and 114.37, respectively. The CUEg and NUEg were declined with the increased N application, and the decline rates of NUEg were higher than those of CUEg. From the flowering period to the ripening period, the N translocation rate of the leaf was the highest, while that of the stem and the root ranked the second and the last, respectively. The N translocation rate of the leaf, stem and root from the flowering period to the ripening period ranged from 73.90% to 78.56%, 38.96% to 67.08% and 24.45% to 37.06% under different treatments. The differences of the N translocation rates of the leaf were slight, whereas those of the stem and root increased with increased N rates. From the flowering period to the ripening period, the C translocation rates of the leaf were positive values, which ranged from 23.16% to 29.08%. It increased generally as the N rates increased, and the differences resulted from N treatments were slight. From the flowering period to the ripening period, the root and the stem still accumulated C, and the C translocation rates of the root and the stem were negative values.【Conclusion】In the areas with the late harvest date of former crops, mechanical transplanting technology with blanket seedling could improve the production capacity of rapeseed. The ability of N metabolism before flowering was higher than that of after-flowering period while the ability of C metabolism had an opposite trend. N supply at early stage was conducive to form nutrition framework, which promoted the accumulation of C and yield formation from the flowering period to the ripening period.

Characteristics of Photosynthetic Nitrogen Allocation in Leaves of Different Positions in Winter Oilseed Rape at Seedling Stage Under Suitable Nitrogen Level

LIU Tao, LU Jian-wei, REN Tao, WANG Wei, WANG Zhen, WANG Shao-hua

Scientia Agricultura Sinica. 2016, 49(18):  3532-3541.  doi:10.3864/j.issn.0578-1752.2016.18.007

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【Objective】 This study was carried out to investigate the effects of nitrogen allocation on the photosynthetic apparatus of leaves at different positions in winter oilseed rape under suitable nitrogen level at seedling stage and to analyze the limiting factors that affect the photosynthetic nitrogen use efficiency by nitrogen nutrition, and provide a theoretical basis for the reasonable application of nitrogen fertilizer.【Method】A field experiment was carried out with designed four nitrogen levels (0, 45, 180, 360 kg·hm^-2, marked as N₀, N₄₅, N₁₈₀ and N₃₆₀, respectively). The dry matter at seedling stage and seed yield were determined. Then the N₀ and N₁₈₀ treatments were selected, the plant leaves were equally divided into 3 groups (upper, middle and lower) by leaf number from top to bottom. Some physiology and photosynthetic parameters (e.g., net photosynthetic rate (Pn _max), nitrogen content (N_A), chlorophyll content (Cc) and soluble protein nitrogen content (N_S)) tested on leaves at different positions were measured to calculate nitrogen allocation in the photosynthetic apparatus (carboxylation, bioenergetics and light-harvesting components). 【Result】 Seed yield was increased significantly by nitrogen fertilization, compared with N₀ treatment, N₄₅, N₁₈₀ and N₃₆₀ were increased by 170%, 505.6% and 604.1%, respectively and the dry matter accumulation was consistent with the yield. Compared with N₀ treatment, N_A, Cc and Pn _max were significantly increased in different leaf positions by nitrogen fertilization, but photosynthetic nitrogen use efficiency (PNUE) has significantly declined in the upper and middle leaves. For nitrogen allocation on the photosynthetic apparatus, the proportion of the carboxylation (P_C), bioenergetics (P_B) and light harvesting system (P_L) in the upper and middle leaves of N₁₈₀ treatment were lower than that of N₀ treatment, but the nitrogen contents of those components were higher than that of N₀ treatment and the increasing extent of the components were 20.6%, 11.8% and 28.8%, respectively. The ratio between soluble protein nitrogen content (N_S) and non-soluble protein nitrogen content (N_non-S) was not significantly influenced by whether nitrogen fertilization or not in the same position leaves, but the photosynthetic component partitioning in N_S or N_non-S was significantly influenced, which the ratio of nitrogen content of the carboxylation (N_C) to N_S was an average of 83.4% in all leaves in N₀ treatment, while that of the N₁₈₀ treatment was only 60.3%. Based on boundary line approach to quantify the influence of each component of the photosynthetic apparatus for PNUE, the results indicated that the influence degrees of P_C and P_B were 26.8% and 42.6%, significantly higher than that of P_L. The influence of nitrogen nutrition on PNUE was dominated by P_C and P_B, which the average proportion reached 77.8%. P_C was the main limiting factor of PNUE in upper leaves, which the influence degree reached 83.3%, while dominated by P_B and P_L in the lower leaves.【Conclusion】 Nitrogen fertilizer had a significant effect on increasing yield of winter rape and the optimum nitrogen application rate was 180 kg·hm^-2. More nitrogen was allocated to photosynthetic apparatus by plant, and the photosynthetic nitrogen can be degraded earlier in the lower leaves under nitrogen deficiency. Suitable nitrogen level can maintain the distribution of the photosynthetic proteins within the types of their proteins. The effect of nitrogen nutrition on photosynthetic nitrogen use efficiency is dominated by allocation of nitrogen to the carboxylation and bioenergetics. The dominant effect by the distribution of the carboxylation was transformed to the dominant effect by the distribution of the light harvesting system and bioenergetics along with the decline of leaf position.

Differences in Carbon Accumulation and Transport in Brassica napus with Different Nitrogen Use Efficiency and Its Effects on Oil Formation

ZHANG Xiao-long, ZHANG Zhen-hua, SONG Hai-xing, YU Jia-ling, GUAN Chun-yun

Scientia Agricultura Sinica. 2016, 49(18):  3542-3550.  doi:10.3864/j.issn.0578-1752.2016.18.008

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【Objective】The differences in carbon (C) accumulation and transport in Brassica napus with different nitrogen use efficiencies (NUE), were studied in order to supply a theoretical basis for elucidating the mechanism of high NUE genotypes in coordinating the contradiction between C and N metabolism and promoting oil formation.【Method】A soil culture experiment was conducted to study the differences of C accumulation and distribution in different organs of B. napus with different NUE at different growth stages (stem elongation stage, flowering stage, silique stage and harvest stage) under normal- and limited-N conditions, and using ¹³C isotope labeling to determine the C redistribution proportion and amount from vegetative organs to reproductive organs, analyze the contribution of C accumulation and transport to grain yield and oil accumulation.【Result】No significant differences in grain oil content between high- and low-NUE genotypes under the normal and limited-N application levels were observed, but the oil yield of high-NUE genotype was significantly higher than that of low-NUE genotype. Compared with limited-N, oil content was slightly decreased, but oil production was increased significantly under normal-N. There was no differences in C accumulation amount between high- and low-NUE genotypes, while the differences in C accumulation amount at different N application levels was significant, C accumulation amount of normal –N was significantly higher than that of limited-N. C allocation proportion in plant organs between high- and low-NUE genotypes was different, C allocation proportion in roots and leaves of high-NUE genotype was higher than that of low-NUE genotype at stem elongation stage and flowering stage, and C allocation proportion in silique and grain of high-NUE genotype was higher than that of low-NUE genotype at silique stage and harvest stage. While, C allocation proportion in stem of high-NUE genotype was lower than that of low-NUE genotype at the whole growth stage, and C allocation proportion in stem and root of high-NUE genotype was lower than that of low-NUE genotype at the whole growth stage. Compared with limited-N, C allocation proportion in leaves was increased at stem elongation stage and flowering stage under normal-N, while C allocation proportion in root was decreased. In addition, C allocation proportion in grain at harvest stage under normal-N was higher than what was observed in limited-N. As the development of plant growth stages, C distribution proportion and amount from vegetative organs to reproductive organs was gradually increased, the differences between genotypes were increased. Redistribution proportion and amount of C from vegetative organs to silique at silique stage and redistribution proportion and amount of C from vegetative organs to grain at harvest stage in high-NUE genotype was higher than that in low-NUE genotype, the significant different was occurred under normal-N. Redistribution proportion and amount of C in silique of high-NUE genotype was lower than that in low-NUE genotype under limited-N, and reversed results was observed under normal-N, the significant difference was occurred under limited-N. The 50% or more of C accumulation at stem elongation stage was left from vegetative organs, which was corresponding with redistribution proportion into reproductive organs, but C reduction proportion was significantly higher than C re-distribution proportion, which was because of the carbohydrate respiration consumption. 【Conclusion】 There was no significant difference in C accumulation between high- and low-NUE B. napus genotypes at different growth stages. However, higher proportion of C was redistributed from vegetative organs to reproductive organs in high-NUE genotype than that in low-NUE genotype at later growth stages. This is one of the important mechanisms for high-NUE genotype possesses with higher C source to relieve the contradictions between C and N, and promote oil formation during the process of grain formation.

Effects of Different Cultivations and Nitrogen Application Methods on Seed Yield and Nitrogen Use Efficiency of Oilseed Rape (Brassica napus L.)

LIU Bo, LU Jian-wei, LI Xiao-kun, CONG Ri-huan, WU Li-shu, YE Chuan, ZHENG Wei, XU Wei-ming, YAO Zhong-qing, REN Tao

Scientia Agricultura Sinica. 2016, 49(18):  3551-3560.  doi:10.3864/j.issn.0578-1752.2016.18.009

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【Objective】Field experiments were carried out to study the effect of different cultivations and nitrogen (N) application methods on seed yield and N use efficiency of oilseed rape (Brassica napus L.) in the main planting areas, and provide theoretical support for high efficient fertilization management in oilseed rape.【Method】 Field trials were conducted in Hubei and Jiangxi provinces during the period of 2010-2011. Three methods of N application (i.e., surface broadcast placement, plough placement, and concentrate placement) were taken to analyze the impact on rapeseed yield, dry matter accumulation and N uptake between the transplanted oilseed rape (Brassica napus L.) (TOR) and direct-sown oilseed rape (DOR).【Result】 Under the same processing conditions, the seed yield level of TOR was higher than DOR and the difference value was 299.1-544.2 kg·hm^-2. The TOR could obtain higher biomass compared to DOR between aboveground and underground according to the dry matter dynamics, furthermore, N accumulation increased significantly by 33.1%-54.8% on average for TOR. Moreover, the agronomic efficiency (AE_N) and N apparent recovery efficiency (RE_N) were significantly increased in TOR compared to the DOR, respectively, which AE_N increased by 20.2% from 6.5 to 7.8 kg·kg^-1, and RE_N increased by 37.5% from 27.6% to 37.5%. N application had a significant effect on seed yield, especially for TOR. Different N application methods resulted in a noticeable impact on yield, dry matter accumulation, N uptake and N use efficiency, following as concentrating> ploughing > broadcasting. The concentrating could increase yield and N accumulation compared to broadcasting, increased yield by 18.2%-23.8% and N accumulation increased by 19.0%-37.0% for TOR and DOR，respectively. Compared with broadcasting, the AE_N of concentrating increased by 27.7% ranged from 6.9 to 8.8 kg·kg^-1 and RE_N increased by 27.2% ranged from 33.3% to 42.3% in TOR, meanwhile, the AE_N of concentrating increased by 31.7% ranged from 5.7 to 7.5 kg·kg^-1 and RE_N increased by 50.7% ranged from 22.0% to 33.2% in DOR. The increase amplitude in underground biomass accounted for 61.8% under concentrating during the whole period and the aboveground portion was 50.5% compared with broadcasting for TOR, while it was 78.5% and 66.7% for DOR, respectively.【Conclusion】 The growth and yield formation were more sensitive to different N application methods in DOR. Dry matter accumulation including underground and aboveground part after anthesis can be coordinately achieved synchronous accumulative under Concentrating. Therefore, both Banding and Holing can efficiency during the oilseed rape production among all the N application methods.

PLANT PROTECTION

Effect of Induced Resistance of Oligosaccharins·Plant Activator Protein on Wheat to WYMV

XU Run-dong, SHENG Shi-ying, YANG Xiu-fen, LIU Yong

Scientia Agricultura Sinica. 2016, 49(18):  3561-3568.  doi:10.3864/j.issn.0578-1752.2016.18.010

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【Objective】Plant activator could trigger effective, persistent and broad-spectrum resistance in plants. The objective of this experiment is to study the resistance induced by oligosaccharins·plant activator protein against wheat yellow mosaic virus (WYMV), thus providing a technical basis for the research and promotion of the use of activator proteins on a large scale.【Method】In laboratory, WYMV susceptible wheat cultivar ‘Aikang 58’ was sowed in the soil that was collected from the WYMV infested field and grown in the incubator under (27±2)℃. When the wheat grown up to five-leaf stage, the 6% oligosaccharins·plant activator protein that was diluted 1 000 times was sprayed. After 7 days, the wheat was put in incubator for 30 days under (12±1)℃, so as to get WYMV inoculated plants. Then the height of wheat plant, chlorophyll content, disease index, and control efficiency were measured or calculated. In filed, wheat was sowed in the plot that infested with WYMV for many years. The oligosaccharins·plant activator protein was sprayed once a week for successive three times of spray when wheat plant was at returning green stage. At the same time, the height of wheat plant, chlorophyll content, disease index, and control efficiency were measured or calculated. Moreover, 20 upper first fully expanded leaves in each plot were taken every week to detect the copy number of WYMV-CP by qPCR during the field investigation. The thousand grain weight, the seeds per ear and the yields were measured and calculated at harvest.【Result】The laboratory experiment showed that after 30 days of the activator spray, the chlorophyll content increased dramatically (P＜0.05), the disease index decreased as the result of the control efficiency reached up to 63.32%, but no difference was found in plant height compared to the control. The field experiment showed that no significant control efficiency after one time spray, but the control efficiency reached up to 46.67% after two times of spray. The suppression rate of the copy number of WYMV-CP reached up to 69.30% in the first week, 85.50% in the second week, and the highest suppression reached up to 99.20% in the third week. However, the chlorophyll content and the height of wheat plants showed no significant differences. Although the seed numbers per ear significantly increased, but no difference was observed in thousand grain weight. As a result, the yields were significantly increased.【Conclusion】Oligosaccharins·plant activator protein could induce wheat plant resistance to WYMV. The copy number of WYMV-CP dramatically decreased in activator protein treated plants. It was showed that the activator could relieve WYMV damage and reduce yield loses in wheat fields.

Molecular Characterization and Biological Function of Argonaute1 in Locusta migratoria

WANG Yan-li, YANG Mei-ling, SONG Tian-qi, MA En-bo, ZHANG Jian-zhen

Scientia Agricultura Sinica. 2016, 49(18):  3569-3577.  doi:10.3864/j.issn.0578-1752.2016.18.011

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【Objective】 MicroRNAs (miRNAs) are small (approximately 22 nt), noncoding RNA molecules that play important roles through post-transcriptional regulation in a wide range of biological process. As an essential component of miRNA silencing complex (RISC), Argonaute1 (AGO1) protein plays a key role in miRNA regulatory pathway. The purpose of this study is to explore the biological function of LmAGO1, and determine its impacts on growth and development in the migratory locust. These results will provide an important theoretical basis for biogenesis mechanism of insect miRNAs and effective pest control. 【Method】 The cDNA sequence of LmAGO1 was identified from the locust transcriptome database by using bioinformatics approaches, and was translated into protein sequence using online protein translation software (ExPASy). The conserved domains were analyzed by SMART based on the deduced protein sequence. A phylogenetic tree of insect AGO was constructed with the locust AGO1, the homologous amino acid sequences from Bombyx mori, Drosophila melanogaster, Tribolium castaneum and other insects using the Phyml program. The double-strand RNAs (dsRNAs) of AGO1 gene were synthesized in vitro using T7 RiboMAX^TM Express RNAi System. The RNA interference (RNAi) experiment was preformed to explore the biological function of LmAGO1 during growth and development in locusts. The dsLmAGO1 was injected into the locust nymphs on day 2 of the 4th-instar and 5th-instar stages, respectively. The injection of dsGFP was used as the control. At the 48 h and 72 h after dsRNA injection, the whole body of locust nymphs was collected for total RNA isolation and cDNA synthesis. The reverse transcript quantitative PCR (RT-qPCR) analyses of the LmAGO1 were performed to determine the gene silencing efficiency. In order to evaluate the influences of the LmAGO1 RNAi on miRNA biogenesis, the five abundantly expressed miRNAs were selected to quantify their expression level by using RT-qPCR after dsLmAGO1 injection.【Result】 The amino acid analysis showed that LmAGO1 protein of locust contains 845 amino acids and has the typical AGO protein family conserved domains, including PAZ (Piwi-Argonaute-Zwille) domain which is located in the region from nucleotide 213 to 348 and PIWI (P-element Induced Wimpy Testis) domain which is located in the region from nucleotide 502 to 804. The phylogenetic analysis showed that LmAGO1 was clustered with the AGO1s of other insect species. The multiple protein sequence alignments indicated that the amino acid sequence identity is 82.2% between LmAGO1and DmAGO1, and is 86.9% between LmAGO1 and BmAGO1, respectively; RNAi results showed that the expression of LmAGO1 was significantly reduced at 48 h and 72 h after dsLmAGO1 injection into locust nymphs. The silencing efficiency of LmAGO1 was 88.1% and 93.0%, respectively. The locust nymphs with dsLmAGO1 treatment did not show any obvious phenotypic defects at the 4th-instar stage. However, compared with dsGFP injected control, the dsLmAGO1 treatment resulted in a high mortality at the 5th-instar stage. A total of 89.3% locust nymphs were dead in dsLmAGO1 injected group. The RT-qPCR results of LmAGO1 showed that LmAGO1 was significantly silenced at 48 h and 72 h after dsRNA injection. Moreover, the expression analysis of miRNA results indicated that the expression levels of miRNA-252 and miRNA-8 were significantly decreased at 48 h after dsLmAGO1 treatments, and that the expressions of miRNA-7, let-7, miRNA-252 and miRNA-8 were significantly down-regulated at 72 h after dsLmAGO1 treatments. 【Conclusion】Besides the role in RSIC formation, LmAGO1 can enhance the processing of miRNA maturation and regulate the normal development in the migratory locust.

SOIL & FERTILIZER·WATER-SAVING IRRIGATION·AGROECOLOGY & ENVIRONMENT

Characteristics of CO₂ Emissions and Changes in Carbon Fractions after Application of Biochar Under Various Fertilization Regimes in Vegetable Soil

WEI Xue-qin, SUN Nan, ZHANG Xu-bo, ZHANG Chong-yu, WANG Dao-long, SHEN Hua-ping

Scientia Agricultura Sinica. 2016, 49(18):  3578-3587.  doi:10.3864/j.issn.0578-1752.2016.18.012

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【Objective】In order to clarify the effects of application of biochar on soil CO₂ emissions and changes in different forms of organic carbon, soil CO₂ emissions and dynamics of dissolved organic carbon (DOC) and microbial biomass carbon (SMBC) were measured after application of biochar under various fertilization regimes.【Method】An incubation was designed to investigate the CO₂ emission and dynamics of DOC and SMBC after application of 2% (biochar/dry soil) and 4% biochar under various fertilization regimes (no fertilizer (CK), organic manure (M), inorganic fertilizer (F), M+F). The correlation among DOC, SMBC and CO₂ were analyzed.【Result】 In the F and M+F treatments added with biochar, soil CO₂ emission rates in the early period (2-8 d) was significantly higher than those without adding biochar, while during the 10-60 d, CO₂ release rates in both treatments were no significant differences. In the CK and M treatments, the CO₂ emission rates were no significant differences between the treatments with or without adding biochar throughout the incubation. In CK treatment, the cumulative CO₂ emission with application of biochar was not differed with that without biochar. In the F and M+F treatments, the cumulative CO₂ emissions were significantly increased after application of 2% and 4% biochar (20.6% and 19.8%, 29.9% and 40.7%, respectively). The correlation showed that there was no relationship between DOC/SMBC and CO₂ emissions without adding biochar, however, there was an obvious correlation when biochar was applied. 【Conclusion】Soil CO₂ emissions did not change when biochar was applied to the unfertilized soil. However, the cumulative CO₂ emission increased by application of biochar into the soil with manure application. Furthermore, the increment of CO₂ emission was dramatically increased when biochar was applied into the soil with inorganic fertilizers plus manure.

The Relationships Between Magnesium Deficiency of Tomato and Cation Balances in Solar Greenhouse Soil

YAN Bo, ZHOU Ting, WANG Hui-min, CHEN Zhu-jun, CAO Jing-yang, LIU Shu-min, ZHOU Jian-bin

Scientia Agricultura Sinica. 2016, 49(18):  3588-3596.  doi:10.3864/j.issn.0578-1752.2016.18.013

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【Objective】It is generally considered that the contents of calcium and magnesium (Mg) in calcareous soil are rich. Therefore, Mg deficiency usually occurs in acidic soil in south China, where the weathering is very strong. However, Mg deficiency of tomato under solar greenhouses in calcareous soil in north China becomes common. It is urgent to understand the reason of Mg deficiency of tomato under solar greenhouses in the region, which will provide scientific knowledge to solve the Mg deficient problem in the solar greenhouse. 【Method】The different degrees of Mg deficiency of tomatoes with the same transplanting times and varieties in the greenhouses in Dazhai, Yangling, Shaanxi were chosen. The degrees of tomato Mg deficiency were divided into three types based on the severity of the symptoms. The three types of Mg deficiency included the leaves without Mg deficiency, the leaves with moderate (half of the upper leaves showed deficiency) and severe (all leaves showed deficiency) Mg deficiency. The soil samples (0-20 cm), lower leaves samples (the leaves between the second and third fruit sets) and upper leaves samples (the fully developed leaves on the top plant) were taken from different greenhouses. The basic soil properties were determined, including soil pH, electric conductivity (EC), organic matter, available nitrogen, phosphorus, and potassium, and soil exchangeable K⁺, Ca²⁺, and Mg²⁺, and their contents in tomato leaves. The ratios of exchangeable K⁺, Ca²⁺, and Mg²⁺ ions, and their saturation percentages in soil colloid were calculated. The fruit yields of different greenhouses were also surveyed. The relationships between Mg deficiency of tomato and the parameters determined were analyzed.【Result】There were significant differences in soil properties between the greenhouses with different degrees of Mg deficiency. The soil EC, contents of nitrate, readily available K in soil of tomato with severe Mg deficiency were significantly increased. The content of exchangeable Mg ions in soils was higher than the critical value of Mg deficiency both in tomatoes with and without Mg deficient symptoms. With the severity of Mg deficiency of tomato, the saturation percentage of K ion was increased and the ratios of Ca/Mg, and K/Mg also increased. On the contrary, the saturation percentages of Ca²⁺ and Mg²⁺ ions, and the ratio of Ca/K were decreased. Compared with tomatoes without Mg deficiency, the saturation percentage of K⁺ and the ratio of K/Mg in soil with moderate Mg deficiency were increased both by 22%, and soil with severe Mg deficiency increased by 56% and 88%, respectively. Compared to soil without tomato Mg deficiency, the ratios of Ca/Mg in soil with severe Mg deficiency was increased by 17%, and the ratios of Ca/K in soil with moderate and severe Mg deficiency were decreased by 19% and 37%, respectively. The soil Ca/Mg ratio of tomato with moderate Mg deficiency was slightly higher than optimum value of Ca/Mg ratio (7.0), and K/Mg ratios was higher than optimum value (0.6) by 47%. The ratios of soil Ca/Mg, and K/Mg were higher than optimum value by 28% and 125%, respectively. The Mg contents in both upper and lower leaves and fruit yield of tomato were significantly and negatively correlated with the readily available K, exchangeable K⁺, saturation percentages of K⁺, and K/Mg ratio, and positively correlated with soil organic matter content and Ca/K ratio; and their correlations with exchangeable Mg²⁺ and its saturation percentages, and the ratio of Ca/Mg were not significant. With the severity of Mg deficiency, the tomato fruit yields were decreased rapidly. The decreasing rates of fruit yields in moderate and severe Mg deficiency were 38% and 60%. 【Conclusion】 The contents of soil exchangeable Mg²⁺ was at optimum levels for tomatoes with or without Mg deficiency; however, the Mg²⁺ saturation percentages was lower. The ratios of Ca/Mg, and K/Mg in soil with different Mg deficiency were imbalance, especially for the K/Mg ratio. The high level of K resulted in imbalances of cation ions was the main reason of Mg deficiency in solar greenhouse of calcareous soil. Therefore, more attentions are needed to deal with this problem.

HORTICULTURE

Effects of After-Reap Soil on Physiological Indexes and Leaf Antioxidant Activity of the Different Apple Cultivars With the Same Rootstock

NI Wei-ru, WANG An-ran, HE Xi-yan, XU Jin, WU Shu-jing, CHEN Xue-sen, MAO Zhi-quan, SHEN Xiang

Scientia Agricultura Sinica. 2016, 49(18):  3597-3607.  doi:10.3864/j.issn.0578-1752.2016.18.014

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【Objective】 Disease caused by after-reap soil is a challenge for planting young apple (Malus domestica) trees with this kind of soil, the effect of after-reap soil on growth and leaf antioxidant activity of different young apple trees were studied for providing evidence for alleviate after-reap disease of apple trees. 【Method】Five apple cultivars (‘Yanfu3’, ‘RedGeneral’, ‘Fuji2001’, ‘Miyakiji’, ‘Shoufu1’) were grafted on rootstocks (M. hupehensis) and planted in pots filled with after-reap soil. The same quantities of five apple cultivars were planted in sterilized soil as control. The dynamic changes of plant growth, chlorophyll content, leaf antioxidant activity, the net photosynthetic rate (Pn) and fluorescent parameters were determined.【Result】After-reap soil had different degrees of inhibition on the growth, chlorophyll content, net photosynthetic rate, fluorescence parameters and leaf antioxidant activity of different cultivars. Compared with sterilized soil (control), there were no significant difference in the growth of ‘Fuji2001’ and ‘Miyakiji’, while other cultivars showed significant differences. From July to September, leaf SOD activity of all apple cultivars in after-reap soil were lower than that of the controls. For example, ‘Fuji2001’ was reduced by 40.24%, 20.96%, and 18.16% compared with the control, and the gap with control becomes small; ‘Yanfu3’, ‘Red General’, ‘Miyakiji’, ‘Shoufu1’ were significantly lower than controls. Leaf POD activity was increased first and then decreased thereafter. In August and September, ‘Fuji2001’ and ‘Miyakiji’ were reduced by 3.02% and 5.76% in average, and there were no significant differences with their controls, however, ‘Yanfu3’, ‘Red General’ and ‘Shoufu1’ were significantly lower than controls from July to September. The leaf CAT activity in ‘Miyakiji’ was higher than other cultivars, it was 27.21% higher than the control in August; in contrast, the leaf CAT activity of other cultivars were all significantly lower than that of controls. From July to September, the net photosynthetic rate of ‘Yanfu3’ and ‘Red General’ was significantly lower than their controls, ‘Shoufu1’ was significantly lower than the control throuthout the experimental period, and others showed no significant differences. ‘Fuji2001’ and ‘Miyakiji’ had no significant differences in fluorescent parameters when compared with controls; ‘Yanfu3’, ‘Red General’ and ‘Shoufu1’ were significantly higher in NPQ than their controls. 【Conclusion】 The effects of after-reap soil on the physiological indexes and leaf antioxidant activity of young apple trees with the same rootstock were different. ‘Fuji 2001’ and ‘Miyakiji’ could resist the effects from the after-reap soil in a certain extent, however, ‘Yanfu3’, ‘Red General’ and ‘Shoufu1’ could not protect themselves well. ‘Fuji2001’ and ‘Miyakiji’ maight be the preferrable varieties for old orchards and further investigations should be carried out.

Estimating the Number of Apple Tree Flowers Based on Hyperspectral Information of a Canopy

LIU Ying, Wang Ke-jian, XIE Rang-jin, Lü Qiang, HE Shao-Lan, YI Shi-lai, ZHENG Yong-qiang, DENG Lie

Scientia Agricultura Sinica. 2016, 49(18):  3608-3617.  doi:10.3864/j.issn.0578-1752.2016.18.015

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【Objective】To study a technology for estimating the number of apple flowers which is based on the hyperspectral image information of a canopy at full-bloom stage, in order to lay a foundation for the establishment of the technologies used for the management and the productivity prediction of the flowers and fruits of a plant. 【Method】 The 5-year-old Malus pumila ‘Mitch Gala’ trees with M₉ clonal rootstocks in the shape of high spindles were studied. The visible and near infrared hyperspectral images of the canopy at full-bloom stage were collected, and the number of the flowers of the trees was selected and then counted manually. Finally, comparatively analyze the effects of the Partial Least Squares (PLS) models based on the original reflectance spectra (OS) and the spectra pretreated by five kinds of methods including savitzky–golay smoothing(SG), standardization of normal variables (SNV), Normalize, first derivation(l^st Der), second derivation(2^nd Der), the PLS, the back-propagation neural network (BPNN) and the least squares support vector machines (LS-SVM) based on characteristic wavelengths obtained by x-loading weight (x-LW) on the accuracy of the real-time estimation of the amount of flowers per unit area per tree. 【Result】 Both the number of flowers per tree and the number of flowers per unit area per tree have high correlation coefficients, which means using the number of flowers per unit area of the canopy as a substitute for the total number of flowers per tree to predict the number of flowers of all the trees is feasible. The number of flowers per unit area per tree had a very significant positive correlation with the reflectivity of the trees’ canopy in the ultraviolet and visible wavelength (308-700 nm), but the correlation between the two was not significant in the near-infrared wavelength (750-1 000 nm). Based on full wavelength, the PLS model based on spectra pretreated by Normalize predicts the number of flowers per unit area per tree most accurately, whose determination coefficients of the calibration sets (R_c²) and of the prediction sets (R_p²) were 0.794 and 0.804, the root-mean-square errors of the calibration sets (RMSEC) and of the prediction sets (RMSEP) were 0.084, 0.062, and whose relative error (RE%) of prediction sets was 3.940. Based on characteristic wavelengths, the stability of BPNN model is bad，the LS-SVM model has better modeling results, with the R_c² and the R_p² being 0.826 and 0.804, RMSEC and the RMSEP being 0.077 and 0.064, the RE% of prediction sets is 12.160. 【Conclusion】 The PLS prediction model based on Normalize pretreatment has the best prediction results of the number of flowers of apple trees in the shape of high spindles per unit area per tree’s canopy, at the same time, after obtaining the spectral data by hyperspectral imager, analysis and processing to extract feature information through simplification, which can provide a basis for the application of multispectral remote sensing data.

STORAGE·FRESH-KEEPING·PROCESSING

Thermal Transition Properties of Soybean Protein Isolate-Corn Starch-Wheat Gluten Mixtures

SU Xiao-fang, LI Shu-jing, ZHANG Bo, ZHANG Jin-chuang, ZHANG Wei

Scientia Agricultura Sinica. 2016, 49(18):  3618-3627.  doi:10.3864/j.issn.0578-1752.2016.18.016

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【Objective】 Thermal transition properties of protein-starch mixtures, which are not fully understood, are important for the food processing, such as optimizing the thermal treatment parameters, controlling final product quality and even saving the processing energy.【Method】 Soybean protein isolate (SPI), corn starch (CS) and wheat gluten (WG) were selected as raw materials. The mixtures of SPI-CS, SPI- WG, WG-CS, SPI-CS-WG were blended at the range of 0-100%. Their thermal transition properties were determined using differential scanning calorimetry (DSC),with water content of 50% and heating rate of 10℃·min^-1 over 20 to 130℃.【Result】 With an increase at the water content from 30 to 70%, onset temperature (T_o) and peak temperature (T_p) of SPI 11 S subunits decreased from 105℃ to 95℃ and from 114℃to 99℃, respectively, meanwhile, thermal transition enthalpy (△H)of 11 S subunit increased from 2.8 to 6.2 J·g^-1.△H of CS increased from 3.6 to 14.1 J·g^-1. No thermal transition was observed in WG at 20 to 130℃. It was probably due to the high moisture increasing the molecular mobility of protein or starch. When the moisture was 50%, compared with 100% ingredient, △H of 11 S subunit in SPI-CS mixtures significantly decreased by about 1.41 J·g^-1 in average, meanwhile, T_o and T_p of CS remarkably increased by about 14℃ and 13℃, respectively. Only thermal transition of SPI was observed in SPI-WG mixtures. T_o and △H of 11 S subunit decreased by 2.40 J·g^-1 in SPI-WG mixtures compared with those of 100% SPI. Similarly, only thermal transition of CS was observed in CS-WG mixtures. In WG-CS mixtures, T_p of CS dramatically increased by about 12℃ compared with 100% CS. In SPI-CS-WG mixtures, when CS:WG was 1﹕1, T_o, T_p and △H of 11 S subunit obviously decreased by about 4℃, 5℃ and 1.64 J·g^-1, respectively, compared with 100 % SPI. Competition between protein and starch for absorbing water was probably the reason for the increasing of thermal transition temperature of CS, and steric hindrance of WG or CS may be the reason for the decreasing thermal transition enthalpy of 11 S subunit.【Conclusion】Addition of wheat gluten or corn starch could decrease thermal transition enthalpy of soybean protein and addition soybean protein isolate or wheat gluten could increase thermal transition temperature of corn starch.

Effects of High Oxygen Modified Atmosphere Packaging on Protein Oxidation, Calpain Activity and Protein Proteolysis of Pork During Postmortem Refrigerated Storage

CHEN Lin, ZHOU Guang-hong, XU Xing-lian, ZHANG Wan-gang

Scientia Agricultura Sinica. 2016, 49(18):  3628-3638.  doi:10.3864/j.issn.0578-1752.2016.18.017

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【Objective】 The objective of this study was to investigate the effect of high oxygen modified atmosphere packaging (HiOx, 80% O₂/20% CO₂）on protein oxidation, calpain activity and protein proteolysis of pork during refrigerated storage. This could help explaining the mechanism of regulation behind HiOx in pork quality. 【Method】 Twelve longissimus dorsimuscles of Duroc × Landrace × Yorkshire crossbred pork were precooled at 4℃ for 24 h, and then randomly assigned to either HiOx or vacuum packaging (VP) and stored for 1, 4 and 6 d at 4℃. The carbonyl content and distribution, sulfhydryl content, sarcomere changes, calpain activity, titin and troponin-T degradation were determined, respectively. 【Result】 Carbonyl content of samples from HiOx was significantly higher than the samples from VP at 4 and 6 d of storage (P＜0.05). HiOx samples showed fluorescence signal in the peripheral area of cell membrane and then the fluorescence signal spread to the internal cellular environment at 1 and 4 d of postmortem refrigerated storage. At 6 d of postmortem refrigerated storage, samples under HiOx presented a strong fluorescence light, with a glaring fluorescence intensity more pronounced in a peripheral area corresponding to the cell membrane and to a region in close contact with the cell membrane, while VP samples presented weaker fluorescence signal. Sulfhydryl content of HiOx samples was significantly lower compared with VP samples at 6 d of postmortem storage (P＜0.05). Samples from VP showed weakening M line, blurry A band as well as broken Z line during postmortem refrigerated storage, whereas samples under HiOx remained less affected. μ-Calpain activity was less in samples from HiOx compared with that from VP at 1 d of storage (P＜0.05). Titin and troponin-T showed less proteolysis in samples from HiOx than that from VP at 4 and 6 d of postmortem refrigerated storage (P＜0.05). 【Conclusion】 Increased protein oxidation under HiOx could inhibit μ-calpain activity and protein proteolysis of pork during postmortem refrigerated storage.

ANIMAL SCIENCE·VETERINARY SCIENCERE·SOURCE INSECT

Sequence Cloning, Tissue Expression Profile and Polymorphism of VRTN Gene in Suhuai Pig

WU Yi-chen, DU Xing, LI Ping-hua, WU Yan, WANG Jun-shun, LIU Hong-lin, LI Qi-fa

Scientia Agricultura Sinica. 2016, 49(18):  3639-3648.  doi:10.3864/j.issn.0578-1752.2016.18.018

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【Objective】The aim of this study is to obtain the coding region sequence of Suhuai VRTN gene, identify its characteristics and expression patterns, analyze the polymorphism of VRTN ins291 in Suhuai pig population. 【Method】The coding sequence of Suhuai pig VRTN gene was isolated by cloning and sequencing. The BioEdit 7.0 software was used to analyze the molecular characteristics and physicochemical properties of Suhuai pig VRTN. Nucleotide and amino acid sequences alignment was performed using Clustal W. Genomic organization and chromosomal locations were investigated by comparing the cDNA and corresponding genomic sequence (UCSC server and NCBI database). Motif analysis was performed using the online programs SMART, and protein tertiary structure was predicted by CPHmodels server. Tissue samples of heart, liver, spleen, lung, kidney, hypothalamus, ovary and skeleton muscle were obtained from adult female Suhuai pigs (n=3). Total RNA was extracted using a Trizol kit, and the expression patterns of VRTN gene of Suhuai pig were analyzed by RT-PCR. The ear samples were obtained from adult female Suhuai pigs (n=106), and genomic DNA was extracted by a conventional phenol-chloroform extraction method. PCR-Gel electrophoresis was performed to analyze the polymorphism of VRTN ins291. 【Result】The full length of the coding sequences of Suhuai pig VRTN gene is 2097 bp, which shared similarities of 84.98%, 74.53%, 85.84% and 86.45% to human, mouse, cattle and sheep, respectively, but only 54.42% to chicken. Genomic structure analysis showed that pig VRTN gene includes 2 exons and 1 intron, and is located on chromosome 7. The Suhuai pig VRTN gene encodes 698 amino acid residues, which shared similarities of 85.55%, 70.07%, 86.20% and 86.06% to human, mouse, cattle and sheep, respectively, but only 51.17% to chicken, indicated that VRTN is conserved in the evolution process of mammalian. Protein structure analysis found that VRTN protein of Suhuai pig contains several typical domains including HTH domain, and comprised 6 α-helices, 5 β-sheets and many random coils. Real-time PCR analysis revealed that the VRTN gene is expressed in heart, liver, spleen, lung, kidney, hypothalamus, ovary and skeleton muscle of Suhuai pig, suggesting that VRTN is widely expressed in various tissues of pig. Genotyping ins291 of VRTN gene in 106 Suhuai pigswas done, and three genotypes were detected. In Suhuai pigs, the frequencies of wt/wt, wt/Q and Q/Q genotypes were 0.717, 0.198 and 0.085. The frequencies of high vertebrate number of Q allele was 0.184. The polymorphic information content of VRTN ins291 in Suhuai pigs was 0.331. The heterozygosity of VRTN ins291 in Suhuai pigs was 0.40. 【Conclusion】 The coding region of VRTN gene was isolated, and its expression showed no tissue-specificity. The presence of high number of vertebrate Q allele in Suhuai pig population was confirmed.

The Effect of MyoG and MEF2a Gene Pyramiding on Slaughter Traits of Ducks

ZHAO Zhong-hai, LI Hui, YI Heng-jie, YANG Sheng-lin, PENG Bang-xing, BU Xiao-yan

Scientia Agricultura Sinica. 2016, 49(18):  3649-3661.  doi:10.3864/j.issn.0578-1752.2016.18.019

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【Objective】 The aim of the present study was to explore the polymerization effects of MyoG and MEF2a genes on duck slaughter traits in order to provide a research foundation for further determining the molecular genetic markers related to duck growth traits, also provide a basis of polygene pyramiding breeding of slaughter traits of ducks.【Method】 A total of 240 individuals of Sansui ducks were selected as experimental material in the study, MyoG gene and MEF2a gene were amplificated and had PRC direct sequencing to detect the single nucleotide mutation (SNPs) of all exons of two genes. Base mutation (SNPs) was detected by direct sequencing of the PCR products. GLM statistical model of SPSS 18.0 software was used to analyze the association with different genotypes corresponding to the SNPs MyoG gene and MEF2a gene with Sansui duck slaughter traits. Based on the single gene association analysis results, the polymorphic sites of MyoG and MEF2a genes with significant influence on slaughter traits were employed to build polymerization genotype by using software PHASE 2.0. 【Result】The result showed that eight SNPs were found in MyoG gene and MEF2a gene, and six SNPs were found in MyoG gene and two SNPs were found in MEF2a gene. In all mutations, the G/C mutation in the g.2977G＞C SNP of MyoG gene resulted in the change of codon from GAG to GAC, and the coding amino acid changed from Glu to Asp; While 2 polymorphic site in the MEF2a gene, the G/A mutation at the g.47915G＞A SNP and the G/A mutation at the g.47918G＞A SNP led to codon change from GAA to AAA and GAT to AAT, and the coding amino acid from Glu/Lys and Asp/Asn. The other five SNPs belonged to synonymous mutations, which did not cause the variation of encoding amino acids. Besides, the SNPs fit with Hardy-Weinberg equilibrium except that g.1131C＞T of MyoG and g.47915G＞A, g.47918G＞A of MEF2a gene which were tested by ?2. The results of correlation analysis between polymorphism sites and slaughter traits showed that the SNP of g.1131C＞T and the SNP of g.2204G＞A in MyoG gene had significant influence over the breast muscle percentage, the body weight and eviscerated weight, and the correspondings to homezygote genotype CC and GG were dominant genotypes. The SNP of g.47915G＞A and g.47918G＞A in MEF2a gene affected the eviscerated weight, and the GA genotype individuals belong to dominant genotype individuals. The g.1131C＞T and g.2204G＞A in MyoG gene and g.47915G＞A and g.47918G＞A in MEF2a gene, which relating to slaughter traits (body weight, eviscerated weight, breast muscle rate and eviscerated rate) were selected and the multiple gene polymerizations (interaction) were analyzed, the results showed that after polymerization, the eviscerated rate of eight kinds of aggregated genotype individuals were not significantly different among different genotypes, the mean value of TTGAGA genotype was the highest, followed by CCGGGA genotype. The differences of other three indexes among different genotypes reached a significant level, and weight and eviscerated weight were positively correlated, and the CCGAGA genotype was the highest, followed by CTGGGA genotype; The average rate of chest muscle of CCGGGG genotype was the highest, followed by CCGGGA genotype. The result indicated that the highest main value of genotype of single gene was CC, GG and GA. After two genes combined, CCGGGA genotype in the four indicators was not the optional combination, which showed that there exist interactive effect between MyoG gene and MEF2a gene.【Conclusion】The results revealed that one single molecular marker breeding maybe not good and cannot obtain good result from the interaction of two genes. However, regnant aggregated genotype individuals was not more than enough, more samples should be selected to investigate the aggregated effect of more genes in further study, and to obtain effective molecular markers for poultry breeding.

Effects of Queen-Rearing Without Larvae-Grafting and Two Esters of Brood Pheromone on the Queen Quality of Apis cerana cerana

ZOU Chui-bin, ZHOU Lin-bin, HU Jing-hua, XI Fang-gui, YUAN Fang, YAN Wei-yu

Scientia Agricultura Sinica. 2016, 49(18):  3662-3670.  doi:10.3864/j.issn.0578-1752.2016.18.020

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【Objective】The objective of this study is to compare the queen quality of queen-rearing with and without larvae-grafting and investigate whether methyl palmitate (MP) and methyl linoleate (ML) used in the process of queen rearing could improve the queen quality.【Method】Three colonies of Apis cerana cerana were chosen as experimental colonies, each colony with 5 combs, were basically the same in the honeybee population, queen age and brood comb area. These colonies were maintained using standard beekeeping techniques. Another strong colony with well egg-laying queen was served as egg-laying colony. The queen was reared at least 3 times in each colony during the queen-rearing with and without larvae-grafting experiment. And the queen was reared at least 3 times for different brood pheromone in each colony with queen-rearing with larvae-grafting method. Stimulated fed the colony to improve the worker nursing enthusiasm during the period of queen-rearing. Comparing the queen quality by testing the acceptance rate of queen cells, the weight, thorax weight and width of newly-emerged queens reared from the queen-rearing with and without larvae-grafting. The gene expression of vitellogenin (Vg) and transferrin (Trf) of the queens were tested by qRT-PCR, and the ovarioles were counted by paraffin section. In order to verify whether MP or ML used in the process of queen-rearing can improve the queen quality, 1µL solution which contains 0, 0.1%, 1.0% and 10.0% of MP or ML was added into the queen cells with 60-63 h old queen larvae, respectively. The queen quality was also detected.【Result】The rate of brood accepted and the percent of queen emerged in queen-rearing without larvae-grafting was 40.87% and 38.52%. In queen-rearing with larvae-grafting it was 74.38% and 69.13%, respectively. So apparently it is easier to accept the wax queen cell than the plastic for workers. No significant difference in the newly-emerged weight, thorax weight and width, ovarioles number in one side and Trf expression was observed between these two queen-rearing methods (P＞0.05). It was also similar in the average value. Nevertheless, Vg expression in queens from queen-rearing without larvae-grafting was significantly higher than that in the larvae-grafting (P＜0.05). 0.1% ML and all concentrations of MP showed no significant effect on all parameters (P＞0.05), and gene expression of Trf was also not different among all treatments (P＞0.05). 1.0% ML significantly reduced the newly-emerged weight, thorax weight and Vg expression of queens (P＜0.05), and 10.0% ML significantly reduced the index, ovarioles number and Vg expression of queens (P＜0.05). There was no significant effect on Trf expression level in both MP and ML (P＞0.05).【Conclusion】The acceptance rate of queen cell was significantly lower (P＜0.05) in queen-rearing without larvae-grafting compared with larvae-grafting. There was no significant difference in the newly-emerged weight, thorax weight and width, ovarioles number and Trf expression of the queens between queen-rearing with and without larvae-grafting (P＞0.05), but Vg expression was considerably higher whereas the acceptance rate of queen cells was lower in queen-rearing without larvae-grafting (P＜0.05). ML and MP used in queen-rearing process could not improve the queen quality.