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    Special Focus: 20 years development of super rice in China
    20 years’ development of super rice in China- The 20th anniversary of the super rice in China
    CHEN Wen-fu, XU Zheng-jin, TANG Liang
    2017, 16(05): 981-983.  DOI: 10.1016/S2095-3119(16)61612-X
    Abstract ( )   PDF in ScienceDirect  
    Section 1: Perspective and review
    Advances and prospects of super rice breeding in China
    TANG Liang, XU Zheng-jin, CHEN Wen-fu
    2017, 16(05): 984-991.  DOI: 10.1016/S2095-3119(16)61604-0
    Abstract ( )   PDF in ScienceDirect  
    Super rice breeding in China has been very successful over the past 3 decades, and the Chinese government has made great efforts to support breeding and cultivation of both conventional and hybrid super rice.  In this review, we focus on the progress in and potential of super rice breeding.  After the establishment of the breeding theory and strategy of “generating an ideotype with strong heterosis through inter-subspecies hybridization, by using gene pyramiding to combine elite traits through composite-crossing to breed super rice varieties with both ideotype and strong hybrid vigor”, a series of major breakthroughs have been achieved in both conventional and super hybrid rice breeding.  A number of new genetic materials with ideotype have been created successfully, and the Ministry of Agriculture of China has approved 156 novel super rice varieties and combinations for commercialization.  During the Developing the Super Rice Varieties Program, great attention has also been paid to the integration and demonstration of the rice production technology.  Collaboration between industry and university researchers has led to technological innovations and initiation of a demonstration system for super hybrid rice.  With widespread cultivation of super rice with higher quality and yield, as well as resistance or tolerance to abiotic or biotic stresses, the yield of rice production per unit has reached a new level.  In addition to increased quality and yield, hybrid rice breeding has also led to improvements in many other agronomic traits, such as resistance to pests and diseases, resistance to lodging, and optimized light distribution in population.  Achievements in super rice breeding and innovation in rice production have made major contributions to the progress in rice sciences and worldwide food security.
    Research progress on the breeding of japonica super rice varieties in Jiangsu Province, China
    WANG Cai-lin, ZHANG Ya-dong, ZHU Zhen, CHEN Tao, ZHAO Qing-yong, ZHONG Wei-gong, YANG Jie, YAO Shu, ZHOU Li-hui, ZHAO Ling, LI Yu-sheng
    2017, 16(05): 992-999.  DOI: 10.1016/S2095-3119(16)61580-0
    Abstract ( )   PDF in ScienceDirect  
    In this study we report the results of a decade-long breeding program for japonica super rice made by Nanjing Branch of Chinese National Center for Rice Improvement in Jiangsu Academy of Agricultural Sciences.  We concluded that selection of parents with good comprehensive traits and complementary advantages and disadvantages of both parents in the hybrid combination, and early selection of high heritability traits in earlier segregating generations could significantly improve the breeding efficiency.  The use of closely-linked functional markers in pyramiding of multiple genes could greatly increase breeding efficiency, avoiding time-consuming and laborious steps that were used in traditional breeding program.  It is also important to coordinate the yield components with variety characteristics such as yield stability, wide adaptability, lodging resistance, and an attractive grain appearance during late growth stage of rice.
    Yield potential and nitrogen use efficiency of China’s super rice
    WANG Fei, PENG Shao-bing
    2017, 16(05): 1000-1008.  DOI: 10.1016/S2095-3119(16)61561-7
    Abstract ( )   PDF in ScienceDirect  
    In 1996, a mega project that aimed to develop rice varieties with super-high yield potential (super rice) was launched by the Ministry of Agriculture (MOA) in China using a combination of the ideotype approach and intersubspecific heterosis.  Significant progress has been made in the last two decades, with a large number of super rice varieties being approved by the MOA and the national average grain yield being increased from 6.21 t ha−1 in 1996 to 6.89 t ha−1 in 2015.  The increase in yield potential of super rice was mainly due to the larger sink size which resulted from larger panicles.  Moreover, higher photosynthetic capacity and improved root physiological traits before heading contributed to the increase in sink size.  However, the poor grain filling of the later-flowering inferior spikelets and the quickly decreased root activity of super rice during grain filling period restrict the achievement of high yield potential of super rice.  Furthermore, it is widely accepted that the high yield potential of super rice requires a large amount of N fertilizer input, which has resulted in an increase in N consumption and a decrease in nitrogen use efficiency (NUE), although it remains unclear whether super rice per se is responsible for the latter.  In the present paper, we review the history and success of China’s Super Rice Breeding Program, summarize the advances in agronomic and physiological mechanisms underlying the high yield potential of super rice, and examine NUE differences between super rice and ordinary rice varieties.  We also provide a brief introduction to the Green Super Rice Project, which aims to diversify breeding targets beyond yield improvement alone to address global concerns around resource use and environmental change.  It is hoped that this review will facilitate further improvement of rice production into the future.
    Yield potential and stability in super hybrid rice and its production strategies
    HUANG Min, TANG Qi-yuan, AO He-jun, ZOU Ying-bin
    2017, 16(05): 1009-1017.  DOI: 10.1016/S2095-3119(16)61535-6
    Abstract ( )   PDF in ScienceDirect  
    China’s Super Hybrid Rice Breeding Program has made significant progress over the past two decades.  In this paper, we reviewed our studies on the yield potential and stability in super hybrid rice and discussed the strategies for super hybrid rice production.  The results of our studies show that rice yield potential has been increased by 12% in super hybrid cultivars as compared with ordinary hybrid and inbred cultivars.  The higher grain yields in super hybrid rice cultivars are attributed to larger panicle size coupled with higher biomass production or higher harvest index.  However, grain yields in super hybrid rice cultivars vary widely among locations depending on soil and climatic factors.  Therefore, it is important to tailor target yield to local conditions in super hybrid rice production.  The target yield for super hybrid rice production can be determined by the average yield method or the regression model method.  Improving soil quality is critical to achieving the target yield in super hybrid rice production.  Favorable crop rotations such as rice-oilseed rape and novel soil management practices, such as biochar addition, are effective approaches to improve soil quality.  It is needed to develop simplified cultivation technologies for super hybrid rice to meet the changes in socioeconomic environments during the period of transition.  There are such technologies as no-tillage direct seeding and mechanized transplanting at high hill density with single seedling per hill.
    Section 2: Efficient utilization of resources
    Effects of nitrogen level on yield and quality of japonica soft super rice
    ZHU Da-wei, ZHANG Hong-cheng, GUO Bao-wei, XU Ke, DAI Qi-gen, WEI Hai-yan, GAO Hui, HU Ya-jie, CUI Pei-yuan, HUO Zhong-yang
    2017, 16(05): 1018-1027.  DOI: 10.1016/S2095-3119(16)61577-0
    Abstract ( )   PDF in ScienceDirect  
    Although studies on the balance between yield and quality of japonica soft super rice are limited, they are crucial for super rice cultivation.  In order to investigate the effects of nitrogen application rate on grain yield and rice quality, two japonica soft super rice varieties, Nanjing 9108 (NJ 9108) and Nanjing 5055 (NJ 5055), were used under seven N levels with the application rates of 0, 150, 187.5, 225, 262.5, 300, and 337.5 kg ha–1.  With the increasing nitrogen application level, grain yield of both varieties first increased and then decreased.  The highest yield was obtained at 300 kg ha–1.  The milling quality and protein content increased, while the appearance quality, amylose content, gel consistency, cooking/eating quality, and rice flour viscosity decreased.  Milling was significantly negatively related with the eating/cooking quality whereas the appearance was significantly positively related with cooking/eating quality.  These results suggest that nitrogen level significantly affects the yield and rice quality of japonica soft super rice.  We conclude that the suitable nitrogen application rate for japonica soft super rice, NJ 9108 and NJ 5055, is 270 kg ha–1, under which they obtain high yield as well as superior eating/cooking quality.
    Grain yield and water use efficiency of super rice under soil water deficit and alternate wetting and drying irrigation
    ZHOU Qun, JU Cheng-xin, WANG Zhi-qin, ZHANG Hao, LIU Li-jun, YANG Jian-chang, ZHANG Jian-hua
    2017, 16(05): 1028-1043.  DOI: 10.1016/S2095-3119(16)61506-X
    Abstract ( )   PDF in ScienceDirect  
    This study investigated if super rice could better cope with soil water deficit and if it could have better yield performance and water use efficiency (WUE) under alternate wetting and drying (AWD) irrigation than check rice.  Two super rice cultivars and two elite check rice cultivars were grown in pots with three soil moisture levels, well watered (WW), moderate water deficit (MWD) and severe water deficit (SWD).  Two cultivars, each for super rice and check rice, were grown in field with three irrigation regimes, alternate wetting and moderate drying (AWMD), alternate wetting and severe drying (AWSD) and conventional irrigation (CI).  Compared with that under WW, grain yield was significantly decreased under MWD and SWD treatments, with less reduction for super rice than for check rice.  Super rice had higher percentage of productive tillers, deeper root distribution, higher root oxidation activity, and greater aboveground biomass production at mid and late growth stages than check rice, especially under WMD and WSD.  Compared with CI, AWMD increased, whereas AWSD decreased grain yield, with more increase or less decrease for super rice than for check rice.  Both MWD and SWD treatments and either AWMD or AWSD regime significantly increased WUE compared with WW treatment or CI regime, with more increase for super rice than for check rice.  The results suggest that super rice has a stronger ability to cope with soil water deficit and holds greater promising to increase both grain yield and WUE by adoption of moderate AWD irrigation.
    Influence of water potential and soil type on conventional japonica super rice yield and soil enzyme activities
    ZHANG Jing, WANG Hai-bin, LIU Juan, CHEN Hao, DU Yan-xiu, LI Jun-zhou, SUN Hong-zheng, PENG Ting, ZHAO Quan-zhi
    2017, 16(05): 1044-1052.  DOI: 10.1016/S2095-3119(16)61575-7
    Abstract ( )   PDF in ScienceDirect  
    We carried out a pool culture experiment to determine the optimal water treatment depth in loam and clay soils during the late growth stage of super rice.  Three controlled water depth treatments of 0–5, 0–10 and 0–15 cm below the soil surface were established using alternate wetting and drying irrigation, and the soil water potential (0 to –25 kPa) was measured at 5, 10 and 15 cm.  A 2-cm water layer was used as the control.  We measured soil enzyme activities, root antioxidant enzyme activities, chlorophyll fluorescence parameters, and rice yield.  The results showed that the 0–5-cm water depth treatment significantly increased root antioxidant enzyme activities in loam soil compared with the control, whereas soil enzyme activities, chlorophyll fluorescence parameters and yield did not differ from those of the control.  The 0–10- and 0–15-cm water depth treatments also increased root antioxidant enzyme activities, whereas soil enzyme activities, chlorophyll fluorescence parameters and yield decreased.  In clay soil, the soil enzyme activities, root antioxidant enzyme activities, chlorophyll fluorescence parameters, and yield did not change with the 0–5-cm water treatment, whereas the 0–10- and 0–15-cm water treatments improved these parameters.  Therefore, the appropriate depths for soil water during the late growth period of rice with a 0 to –25 kPa water potential were 5 cm in loam and 15 cm in clay soil.
    Effects of soilless substrates on seedling quality and the growth of transplanted super japonica rice
    LEI Wu-sheng1, 2, DING Yan-feng1, LI Gang-hua1, TANG She1, WANG Shao-hua1
    2017, 16(05): 1053-1063.  DOI: 10.1016/S2095-3119(16)61588-5
    Abstract ( )   PDF in ScienceDirect  
    This study was conducted to investigate the effects of soilless substrates of hydroponically grown long-mat seedlings (HLMS) on seedling quality and field growth characteristics of transplanted super japonica rice.  A widely grown conventional super japonica rice cultivar (Wuyunjing 23) was selected as the test material.  The effect of HLMS on seedling quality, mechanical transplantation quality, field growth characteristics, yield, and benefit-cost ratio were compared with seedlings grown in organic substrates and traditional nutritive soil, which was selected as the control.  Root number, root twisting power and root activity of seedlings cultivated by HLMS were decreased compared to that of the organic substrates and control.  However, seedling root length as well as aboveground growth were increased compared to the organic substrates and control seedlings.  In the HLMS, the content of gibberellin acid (GA3) decreased while abscisic acid (ABA) content increased compared to that of the organic substrates and control seedlings.  During the early stages after transplanting, the re-greening of HLMS was delayed compared to that of the organic substrates and control seedlings.  Nevertheless, there were no significant differences in tiller dynamics and crop yield among the HLMS, organic substrates and control treatments.  The effects of HLMS on seedling production were similar to those of the organic substrates and traditional nutritive soil in the present study, suggesting that HLMS have the potential to replace traditional nutritive soil in seedling production without decreasing crop yield.  Finally, it is important to reduce organic substrates and topsoil dependence during rice seedling production and worthwhile to consider HLMS popularization and its application on a larger scale.
    Effects of straw and biochar addition on soil nitrogen, carbon, and super rice yield in cold waterlogged paddy soils of North China
    CUI Yue-feng, MENG Jun, WANG Qing-xiang, ZHANG Wei-ming, CHENG Xiao-yi, CHEN Wen-fu
    2017, 16(05): 1064-1074.  DOI: 10.1016/S2095-3119(16)61578-2
    Abstract ( )   PDF in ScienceDirect  
    The additions of straw and biochar have been suggested to increase soil fertility, carbon sequestration, and crop productivity of agricultural lands.  To our knowledge, there is little information on the effects of straw and biochar addition on soil nitrogen form, carbon storage, and super rice yield in cold waterlogged paddy soils.  We performed field trials with four treatments including conventional fertilization system (CK), straw amendment 6 t ha–1 (S), biochar amendment 2 t ha–1 (C1), and biochar amendment 40 t ha–1 (C2).  The super japonica rice variety, Shennong 265, was selected as the test crop.  The results showed that the straw and biochar amendments improved total nitrogen and organic carbon content of the soil, reduced N2O emissions, and had little influence on nitrogen retention, nitrogen density, and CO2 emissions.  The S and C1 increased NH4+-N content, and C2 increased NO3-N content.  Both S and C1 had little influence on soil organic carbon density (SOCD) and C/N ratio.  However, C2 greatly increased SOCD and C/N ratio.  C1 and C2 significantly improved the soil carbon sequestration (SCS) by 62.9 and 214.0% (P<0.05), respectively, while S had no influence on SCS.  C1 and C2 maintained the stability of super rice yield, and significantly reduced CH4 emissions, global warming potential (GWP), and greenhouse gas intensity (GHGI), whereas S had the opposite and negative effects.  In summary, the biochar amendments in cold waterlogged paddy soils of North China increased soil nitrogen and carbon content, improved soil carbon sequestration, and reduced GHG emission without affecting the yield of super rice.
    Section 3: Quality improvement of super rice
    Discussion on strategy of grain quality improvement for super high yielding japonica rice in Northeast China
    MAO Ting, LI Xu, JIANG Shu-kun, TANG Liang, WANG Jia-yu, XU Hai, XU Zheng-jin
    2017, 16(05): 1075-1083.  DOI: 10.1016/S2095-3119(16)61563-0
    Abstract ( )   PDF in ScienceDirect  
    japonica rice is mainly distributed in Northeast China and accounts for 44.6% of the total cultivated area of japonica rice in China.  The comprehensive using of inter-subspecies heterosis is the main breeding mode of super japonica rice varieties in this region.  Improving rice quality at relative high yielding level is the current research focus.  Performing crosses between indica and japonica lines allows for the recombination of regulatory genes and genetic backgrounds, leading to complicated genetic rice quality characteristics, which can be used to explore patterns of quality improvement.  In the present study, we utilize recombinant inbred lines (RILs) derived from indica-japonica hybridization to analyze the effect factors of rice quality derived from genetic factors, which contain both regulatory genes concerning rice quality and genetic backgrounds’ random introduction frequency coming from indica (Di value), and the improvement strategy was further discussed.  The regulatory genes involved in amylase content (Wx) and nitrogen utilization efficiency (NRT1.1B) were the major factors affecting the amylose content (AC) and protein content (PC) in RILs, respectively.  Both the Di value and the major grain width gene (GS5) had regulatory effects on milled rice width (MRW) in RILs, and their interaction explained the major variance of MRW in the RILs.  With the mediation of MRW and chalkiness degree (C), Di value had a further impact on head rice rate (HR), which was relatively poor when the Di value was over 40%.  In Northeast China, the Di value should be lowered by backcrossing or multiple crosses during the breeding of indica-japonica hybridization to maintain the whole better HR and further to emphasize the use of favorable genes in individual selection.
    Identification of QTLs for seed storability in rice under natural aging conditions using two RILs with the same parent Shennong 265
    DONG Xiao-yan, FAN Shu-xiu, LIU Jin, WANG Qi, LI Mei-rong, JIANG Xin, LIU Zhen-yu, YIN Ye-chao, WANG Jia-yu
    2017, 16(05): 1084-1092.  DOI: 10.1016/S2095-3119(16)61579-4
    Abstract ( )   PDF in ScienceDirect  
    Seed storability (SS) is an important trait for agronomic production and germplasm preservation in rice (Oryza sativa L.).  Quantitative trait locus (QTL) for seed storability in three storage periods was identified using two sets of recombinant inbred lines (RILs) derived from the crosses with a common female parent Shennong 265 (SN265).  Ten QTLs for seed storability were detected on chromosomes 1, 2, 3, 4, 6, 8, and 12 in SL-RILs (SN265/Lijiangxingtuanheigui (LTH)), and a total of 12 QTLs were identified on chromosomes 2, 3, 4, 6, 9, and 10 in SH-RILs (SN265/Luhui 99 (LH99)) in different storage periods.  Among these QTLs, five major QTLs were identified in more than one storage period.  The qSS3-1, qSS3-2, qSS12-1, and qSS12-2 were detected in SL-RILs.  Similarly, qSS2-2, qSS2-3, qSS6-2, qSS6-3, qSS6-4, qSS9-1, and qSS9-2 were detected in SH-RILs.  In addition, the maximum phenotypic variation was derived from the qSS6-1 and qSS9-2, explaining 53.58 and 29.09%, respectively, while qSS6-1 was a new stable QTL for seed storability.  These results provide an opportunity for pyramiding and map-based cloning major QTLs for seed storability in rice.
    Crop Genetics · Breeding · Germplasm Resources
    Rapid gene expression change in a novel synthesized allopolyploid population of cultivated peanut×Arachis doigoi cross by cDNA-SCoT and HFO-TAG technique
    HE Liang-qiong1, TANG Rong-hua1, JIANG Jing1, XIONG Fa-qian1, HUANG Zhi-peng1, WU Hai-ning1, GAO Zhong-kui1, ZHONG Rui-chun1, HE Xin-hua2, HAN Zhu-qiang1
    2017, 16(05): 1093-1102.  DOI: 10.1016/S2095-3119(16)61462-4
    Abstract ( )   PDF in ScienceDirect  
    Allopolyploidy has played an important role in plant evolution and heterosis.  Recent studies indicate that the process of wide hybridization and (or) polyploidization may induce rapid and extensive genetic and epigenetic changes in some plant species.  To better understand the allopolyploidy evolutionism and the genetic mechanism of Arachis interspecific hybridization, this study was conducted to monitor the gene expression variation by cDNA start codon targeted polymorphism (cDNA-SCoT) and cDNA high-frequency oligonucleotide-targeting active gene (cDNA-HFO-TAG) techniques, from the hybrids (F1) and newly synthesized allopolyploid generations (S0-S3) between tetraploid cultivated peanut Zhongkaihua 4 with diploid wild one Arachis doigoi. Rapid and considerable gene expression variations began as early as in the F1 hybrid or immediately after chromosome doubling.  Three types of gene expression changes were observed, including complete silence (gene from progenitors was not expressed in all progenies), incomplete silence (gene expressed only in some progenies) and new genes activation.  Those silent genes mainly involved in RNA transcription, metabolism, disease resistance, signal transduction and unknown functions.  The activated genes with known function were almost retroelements by cDNA-SCoT technique and all metabolisms by cDNA-HFO-TAG.  These findings indicated that interspecific hybridization and ploidy change affected gene expression via genetic and epigenetic alterations immediately upon allopolyploid formation, and some obtained transcripts derived fragments (TDFs) probably could be used in the research of molecular mechanism of Arachis allopolyploidization which contribute to thwe genetic diploidization of newly formed allopolyploids.  Our research is valuable for understanding of peanut evolution and improving the utilization of putative and beneficial genes from the wild peanut.
    Molecular cloning and functional characterization of MdPIN1 in apple
    AN Jian-ping, LIU Xin, LI Hao-hao, YOU Chun-xiang, SHU Jing, WANG Xiao-fei, HAO Yu-jin
    2017, 16(05): 1103-1111.  DOI: 10.1016/S2095-3119(16)61554-X
    Abstract ( )   PDF in ScienceDirect  
    Auxin has been identified to play critical roles in regulating plant growth and development.  The polar transport of auxin is regulated by auxin transporters.  In the present study, an auxin efflux carrier gene MdPIN1 was cloned from Malus×domestic, Royal Gala, and introduced into wild-type Arabidopsis thaliana (Col-0).  The transgenic plants exhibited the phenotype of inhibition of primary root (PR) elongation and increased lateral root (LR) number in compared with Col-0.  Overexpression of MdPIN1 affected auxin transport, and enhanced phototropic responses and geotropism reaction, whereas had no significant difference in the auxin biosynthesis.  These findings suggest that the MdPIN1 gene plays a vital role in auxin transport and root development.
    Establishment of a tetracycline-off and heat shock-on gene expression system in tobacco
    ZHOU You, LI Jin-hua, PAN Yu, ZHENG Yu, PAN Yang-lu, DING Yu-mei, SU Cheng-gang, ZHANG Xing-guo
    2017, 16(05): 1112-1119.  DOI: 10.1016/S2095-3119(16)61514-9
    Abstract ( )   PDF in ScienceDirect  
    The tetracycline (Tet)-off gene expression regulation system based on the TetR-VP16/Top10 construct has not been widely utilized in plants, for its highly expressed TetR-VP16 activator is toxic to some plants and repeatedly replenishing tetracycline to turn off the constitutively active system is a tedious process.  To solve these problems, a Tet-off and heat shock (HS)-on gene expression regulation system was constructed in this study.  This system is composed of a chimeric transactivator gene TetR-HSF that is derived from a Tet repressor (TetR) and a HS transcription factor (HSF) controlled by a HS promoter HSP70m, and a Tet operator containing hybrid promoter, Om35S, that drives expression of the β-glucuronidase (GUS) gene.  The resultant system yields a GUS expression pattern similar to that of the HSP70m promoter under inducing temperatures and at 35 and 40°C drives GUS expression to a similar level as the Cauliflower mosaic virus (CaMV) 35S promoter.  Further examination revealed that the TetR-HSF and GUS genes were induced by HS, reaching peak expression after 1 and 6 h treatment, respectively, and the HS induction of the expression system could be inhibited by Tet.  This system will provide a useful tool for transgenic studies of plants in the laboratory and in the field, including transgene function analysis, agronomic trait improvement, biopharmaceutical protein production and others.
    Animal Science · Veterinary Science
    Effect of sucrose on cryopreservation of pig spermatogonial stem cells
    PAN Chuan-ying, YU Shuai, ZHANG Peng-fei, WANG Bo, ZHU Zhen-dong, LIU Ying-ying, ZENG Wen-xian
    2017, 16(05): 1120-1129.  DOI: 10.1016/S2095-3119(16)61489-2
    Abstract ( )   PDF in ScienceDirect  
    Sucrose is known to play an important role in the cryopreservation of sperm and female gonads; however, its effect on the cryopreservation of pig spermatogonial stem cells (pSSCs) has not been tested.  The aim of this work was to study the effect of sucrose during pSSC cryopreservation and to find the most effective concentration in freezing medium.  pSSCs were cryopreserved with freezing media containing different concentrations of sucrose (70, 140, 210, and 280 mmol L–1) and a control group without sucrose.  The survival rates, plasma membrane integrity, and mitochondrial membrane potential of thawed cells were detected by trypan blue (TB) staining, SYBR-14/propidium iodide (PI) dual staining, and JC-1 staining, respectively.  All the staining results showed an obvious increase in cell survival in the sucrose-treated groups as compared to that in the control group, with the exception of 280 mmol L–1 sucrose.  Moreover, the 210 mmol L–1 sucrose group yielded the highest survival rate among all the groups (P<0.05).  The results of SYBR-14/PI dual staining and JC-1 staining were consistent with those of TB staining as above described.  Quantitative real-time PCR (qRT-PCR) indicated that the mRNA levels of three apoptosis-promoting genes (BAX, APAF1 and CASPASE9) were significantly higher in thawed cells than in cells before freezing (P<0.05).  Moreover, the mRNA level of one anti-apoptotic gene (XIAP) was significantly lower in thawed cells than in cells before freezing (P<0.05).  When comparing the mRNA expression of apoptosis-related genes in thawed cells, the mRNA level of the anti-apoptotic genes in the control group was significantly lower than that in the sucrose-treated
    groups (P<0.05).  Western blot analyses showed that the expression levels of cleaved CASPASE9, CASPASE3 and PARP-1 in the sucrose-treated groups were lower than those in the control group and were the lowest in the 210 mmol L–1 sucrose group.  Both qRT-PCR and Western blot analyses suggested that sucrose inhibited cell apoptosis during freezing and thawing.  Briefly, sucrose promoted pSSCs survival after freezing and thawing, especially at a concentration of 210 mmol L–1, which possibly assisted pSSC dehydration and inhibited cell apoptosis.  These findings hold great promise for further studies of the regulatory mechanism of proliferation and differentiation of pSSCs. 
    Comparison of rumen archaeal diversity in adult and elderly yaks (Bos grunniens) using 16S rRNA gene high-throughput sequencing
    WANG Li-zhi, WANG Zhi-sheng, XUE Bai, WU De, PENG Quan-hui
    2017, 16(05): 1130-1137.  DOI: 10.1016/S2095-3119(16)61454-5
    Abstract ( )   PDF in ScienceDirect  
    This study was conducted to investigate the phylogenetic diversity of archaea in the rumen of adult and elderly yaks.  Six domesticated female yaks, 3 adult yaks ((5.3±0.6) years old), and 3 elderly yaks ((10.7±0.6) years old), were used for the rumen contents collection.  Illumina MiSeq high-throughput sequencing technology was applied to examine the archaeal composition of rumen contents.  A total of 92 901 high-quality archaeal sequences were analyzed, and these were assigned to 2 033 operational taxonomic units (OTUs).  Among these, 974 OTUs were unique to adult yaks while 846 OTUs were unique to elderly yaks; 213 OTUs were shared by both groups.  At the phylum level, more than 99% of the obtained OTUs belonged to the Euryarchaeota phylum.  At the genus level, the archaea could be divided into 7 archaeal genera.  The 7 genera (i.e., Methanobrevibacter, Methanobacterium, Methanosphaera, Thermogymnomonas, Methanomicrobiu, Methanimicrococcus and the unclassified genus) were shared by all yaks, and their total abundance accounted for 99% of the rumen archaea.  The most abundant archaea in elderly and adult yaks were Methanobrevibacter and Thermogymnomonas, respectively.  The abundance of Methanobacteria (class), Methanobacteriales (order), Methanobacteriaceae (family), and Methanobrevibacter (genus) in elderly yaks was significantly higher than in adult yaks.  In contrast, the abundance of Thermogymnomonas in elderly yaks was 34% lower than in adult yaks, though the difference was not statistically significant.  The difference in abundance of other archaea was not significant between the two groups.  These results suggested that the structure of archaea in the rumen of yaks changed with age.  This is the first study to compare the phylogenetic differences of rumen archaeal structure and composition using the yak model. 
    Protein requirements of early-weaned Dorper crossbred female lambs
    MA Tao, DENG Kai-dong, TU Yan, ZHANG Nai-feng, SI Bing-wen, XU Gui-shan, DIAO Qi-yu
    2017, 16(05): 1138-1144.  DOI: 10.1016/S2095-3119(16)61455-7
    Abstract ( )   PDF in ScienceDirect  
    The net protein (NP) and metabolizable protein (MP) requirements of Dorper crossbred female lambs from 20 to 35 kg body weight (BW) were assessed in a comparative slaughter trial.  Thirty-five Dorper×thin-tailed Han crossbred lambs weaned at approximately 50 d of age ((19.1±2.37) kg of BW) were used.  Seven randomly selected lambs were slaughtered at the beginning of the trial as baseline group (BL).  An intermediate group of seven randomly selected lambs fed ad libitum (AL) intake was slaughtered when the lambs reached an average BW of 28.6 kg.  The remaining 21 lambs were allotted randomly to three levels of dry matter intake: AL or restricted to 70 or 40% of the AL intake.  All lambs were slaughtered when the sheep fed AL intake reached 35 kg of BW.  Total body N and N retention were determined.  The results showed that the maintenance requirements for NP and MP were 1.75 and 3.37 g kg–1 metabolic shrunk body weight (SBW0.75), respectively.  The partial efficiency of protein use for maintenance was 0.52.  The NP requirements for growth ranged from 10.9 to 42.4 g d–1 for the lambs gaining 100 to 350 g d–1 from 20 to 35 kg BW.  The partial efficiency of MP for growth was 0.52.  In conclusion, the NP and MP requirements for the maintenance and growth of Dorper crossbred female lambs were lower than those reported by AFRC (1993) and NRC (2007) recommendations.
    Role of duck plague virus glycoprotein C in viral adsorption: Absence of specific interactions with cell surface heparan sulfate
    JING Yan-chun, WU Ying, SUN Kun-feng, WANG Ming-shu, CHENG An-chun, CHEN Shun, JIA Ren-yong, ZHU De-kang, LIU Ma-feng, YANG Qiao, JING Bo, CHEN Xiao-yue
    2017, 16(05): 1145-1152.  DOI: 10.1016/S2095-3119(16)61550-2
    Abstract ( )   PDF in ScienceDirect  
    Many mammalian herpes viruses utilize heparan sulfate (HS) moieties present on cell surface proteoglycans as receptors for cell entry, and this process also requires viral glycoprotein C (gC) homologues.  However, our understanding of the role of gC in facilitating attachment of other alpha-herpes viruses such as the duck plague virus (DPV) remains preliminary.  To study the role of gC during DPV infection, we used a gC-deleted mutant virus (DPV-ΔgC-EGFP).  Examination of the viral copy number by real-time PCR, as well as time course studies of viral adsorption and proliferation revealed that gC was involved in the viral binding to the cell surface.  The affinity of viral glycoproteins (gB-DPV, gC-DPV, and gE-DPV) to HS was assessed using a prokaryotic expression system and HiTrapTM Heparin HP column chromatography.  In addition, to confirm that gC played a role in the interaction between DPV and HS, viruses were treated with the HS analogue heparin and host cells were treated with its inhibitors heparinase prior to exposure to DPV-ΔgC-EGFP or wild-type strain Chinese virulent duck plague virus (DPV-CHv).  The effects of heparin and heparinase on virus infectivity demonstrated that function of gC on viral adsorption is independent of interactions between gC and heparin sulfate on cell surface.  All in all, this study demonstrated that the gC of DPV can mediate viral adsorption in an HS-independent manner, which distinguish it from the gC of some other alpha-herpes viruses.  Future studies will be required to identify the receptors involved in gC protein binding to cells.  This work provides us a foundation for further studies of examining the roles of gC in the adsorption during duck plague virus infection.
    Soil & Fertilization﹒Irrigation﹒Plant Nutrition﹒ Agro-Ecology & Environment
    Response of yield, quality, water and nitrogen use efficiency of tomato to different levels of water and nitrogen under drip irrigation in Northwestern China
    DU Ya-dan, CAO Hong-xia, LIU Shi-quan, GU Xiao-bo, CAO Yu-xin
    2017, 16(05): 1153-1161.  DOI: 10.1016/S2095-3119(16)61371-0
    Abstract ( )   PDF in ScienceDirect  
    The objective of this study was to investigate the effects of applying different amounts of water and nitrogen on yield, fruit quality, water use efficiency (WUE), irrigation water use efficiency (IWUE) and nitrogen use efficiency (NUE) of drip-irrigated greenhouse tomatoes in northwestern China.  The plants were irrigated every seven days at various proportions of 20-cm pan evaporation (Ep).  The experiment consisted of three irrigation levels (I1, 50% Ep; I2, 75% Ep; and I3, 100% Ep) and three N application levels (N1, 150 kg N ha–1; N2, 250 kg N ha–1; and N3, 350 kg N ha–1).  Tomato yield increased with the amount of applied irrigation water in I2 and then decreased in I3.  WUE and IWUE were the highest in I1.  WUE was 16.5% lower in I2 than that in I1, but yield was 26.6% higher in I2 than that in I1.  Tomato yield, WUE, and IWUE were significantly higher in N2 than that in N1 and N3.  NUE decreased with increasing N levels but NUE increased with increase the amount of water applied.  Increasing both water and N levels increased the foliar net photosynthetic rate.  I1 and I2 treatments significantly increased the contents of total soluble solids (TSS), vitamin C (VC), lycopene, soluble sugars (SS), and organic acids (OA) and the sugar:acid ratio in the fruit and decreased the nitrate content.  TSS, VC, lycopene, and SS contents were the highest in N2.  The harvest index (HI) was the highest in I2N2.  I2N2 provided the optimal combination of tomato yield, fruit quality, and WUE.  The irrigation and fertilisation regime of 75% Ep and 250 kg N ha–1 was the best strategy of water and N management for the production of drip-irrigated greenhouse tomato.
    Ridge-furrow rainwater harvesting with supplemental irrigation to improve seed yield and water use efficiency of winter oilseed rape (Brassica napus L.)
    GU Xiao-bo, LI Yuan-nong, DU Ya-dan, YIN Min-hua
    2017, 16(05): 1162-1172.  DOI: 10.1016/S2095-3119(16)61447-8
    Abstract ( )   PDF in ScienceDirect  
    Ridge-furrow rainwater harvesting (RFRH) planting pattern can lessen the effect of water deficits throughout all crop growth stages, but water shortage would remain unavoidable during some stages of crop growth in arid and semiarid areas.  Supplemental irrigation would still be needed to achieve a higher production.  Field experiments were conducted for two growing seasons (2012–2013 and 2013–2014) to determine an appropriate amount of supplemental irrigation to be applied to winter oilseed rape at the stem-elongation stage with RFRH planting pattern.  Four treatments, including supplemental irrigation amount of 0 (I1), 60 mm (I2) and 120 mm (I3) with RFRH planting pattern and a control (CK) irrigated with 120 mm with flat planting pattern, were set up to evaluate the effects of supplemental irrigation on aboveground dry matter (ADM), nitrogen nutrition index (NNI), radiation use efficiency (RUE), water use efficiency (WUE), and seed yield and oil content of the oilseed rape.  Results showed that supplemental irrigation improved NNI, RUE, seed yield and oil content, and WUE.  However, the NNI, RUE, seed yield and oil content, and WUE did not increase significantly or even showed a downward trend with excessive irrigation.  Seed yield was the highest in I3 for both growing seasons.  Seed yield and WUE in I3 averaged 3 235 kg ha–1 and 8.85 kg ha–1 mm–1, respectively.  The highest WUE was occurred in I2 for both growing seasons.  Seed yield and WUE in I2 averaged 3 089 kg ha–1 and 9.63 kg ha–1 mm–1, respectively.  Compared to I3, I2 used 60 mm less irrigation amount, had an 8.9% higher WUE, but only 4.5 and 0.4% lower seed yield and oil content, respectively.  I2 saved water without substantially sacrificing yield or oil content, so it is recommended as an appropriate cultivation and irrigation schedule for winter oilseed rape at the stem-elongation stage.
    Peach yield and fruit quality is maintained under mild deficit irrigation in semi-arid China
    ZHOU Han-mi, ZHANG Fu-cang, Roger Kjelgren, WU Li-feng, GONG Dao-zhi, ZHAO Na, YIN Dong-xue, XIANG You-zhen, LI Zhi-jun
    2017, 16(05): 1173-1183.  DOI: 10.1016/S2095-3119(16)61571-X
    Abstract ( )   PDF in ScienceDirect  
    We conducted a two-year study of deficit irrigation impact on peach yield and quality in semi-arid northwest China.  Over two years, four-year-old peach trees were irrigated at 100, 75, 50 and 25% of peach evapotranspiration (ETc), here, ETc= Coefficient (Kc)×Local reference evapotranspiration (ETo).  During the April-July fruit production season we measured root zone soil water depletion, sap flow velocity, net photosynthetic rate (Pn), transpiration rate (Tr), stomatal conductance (Gs), water use efficiency (WUE=Pn/Tr), fruit quality, and yield under a mobile rain-out shelter.  Increased soil water depletion reasonably mirrored decreasing irrigation rates both years, causing progressively greater water stress.  Progressive water stress lowered Gs, which in turn translated into lower Tr as measured by sap flow.  However, mild deficit irrigation (75% ETc) constricted Tr more than PnPn was not different between 100 and 75% ETc treatments in both years, and it decreased only 5–8% in June with higher temperature than that in May with cooler temperature.  Concurrently under 75% ETc treatment, Tr was reduced, and WUE was up to 13% higher than that under 100% ETc treatment.  While total fruit yield was not different under the two treatments, because 75% ETc treatment had fewer but larger fruit than 100% ETc trees, suggesting mild water stress thinned fruit load.  By contrast, sharply decreased Tr and Pn of the driest treatments (50 and 25% ETc) increased WUE, but less carbon uptake impacted total fruit yield, resulting 13 and 33% lower yield compared to that of 100% ETc treatment.  Irrigation rates affected fruit quality, particularly between the 100 and 75% ETc trees.  Fewer but larger fruit in the mildly water stressed  trees (75% ETc) resulted in more soluble solids and vitamin C, firmer fruit, and improved sugar:acid ratio and fruit color compared to the 100% ETc treatment.  Overall, trees deficit irrigated at 75% ETc maintained yield while improving fruit quality and using less water. 
    Water and nutrient management effects on water use and yield of drip irrigated citrus in vertisol under a sub-humid region
    P Panigrahi, A K Srivastava
    2017, 16(05): 1184-1194.  DOI: 10.1016/S2095-3119(16)61500-9
    Abstract ( )   PDF in ScienceDirect  
    Scarcity of water and nutrients in orchards are the major causes of low productivity and decline of citrus in tropics.  With a hypothesis that the optimal amount of water and nutrients application through drip irrigation (DI) could save substantial irrigation and fertilizers comparative to that under traditional basin irrigation (BI) with band placement of fertilizer (BPF), this study was conducted in citrus in vertisol of central India.  Three DI regimes: I1, I2 and I3 scheduled at 50% class-A pan evaporation rate (Ep), 75% Ep, and 100% Ep along with three fertilizer doses: F1, F2 and F3 at 50% recommended dose of fertilizer (RDF, N:P2O5:K2O=600 g:200 g:100 g), 75% of RDF and 100% of RDF were applied to mandarin plants respectively.  BI with band placement of fertilizer (BPF) at 100% RDF was taken for comparison.  All the drip-fertigation treatments (except I1F1) produced higher plant growth and fruit yield, with better quality fruits compared with BI+BPF.  The highest fruit yield (16.39 t ha–1), water use efficiency (3.9 kg m–3) and fertilizer use efficiency (87.3 kg kg–1) were observed in I2F2.  The concentrations of N, K and Fe in leaves were significantly higher in I2F2 compared to other treatments.  The leaf photosynthesis, stomatal conductance (Gs) and transpiration were the highest in I3F3.  However, leaf water use efficiency (LWUE, photosynthesis/transpiration) was the highest in I2F2.  The overall results of this study demonstrated that the application of optimum quantity of water and fertilizers (I2F2) through DI could be a productive and water efficient option in citrus production in vertisol.