Scientia Agricultura Sinica

Genome-Wide Association Analysis for Rice Submergence Seedling Rate

SUN Kai, LI DongXiu, YANG Jing, DONG JiChi, YAN XianCheng, LUO LiXin, LIU YongZhu, XIAO WuMing, WANG Hui, CHEN ZhiQiang, GUO Tao

Scientia Agricultura Sinica. 2019, 52(3): 385-398. doi:10.3864/j.issn.0578-1752.2019.03.001

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【Background】 The low seedling rate of direct seeding rice is an important factor limiting its yield. Mining rice materials with high seed viability and low oxygen germination ability is the key to improving the seedling rate and solving the problem of seedlings in direct seeding rice. 【Objective】 The key phenotypic traits affecting the rate of emergence and tolerance of seedlings were analyzed, and the relevant genetic loci and candidate genes were mined to provide a theoretical and material basis for the study of direct seeding rice cultivars and the mechanism of resistance to flooding. 【Method】 Using 200 rice germplasms from a wide range of sources. The germination test was carried out in an aerobic environment, and the seed viability phenotype was measured including germination rate, germination index and viability index; The coleoptile length and coleoptile diameter were measured under hypoxic conditions. The flood-tolerant seedling experiment was carried out, the water depth was 10cm, and the flood-tolerant seedling rate was measured after 20d. The correlation between various traits was analyzed, and the key traits affecting the rate of tolerance to flooding were explored. Genome-wide association analysis was performed on the above six phenotypes by simplified genome sequencing, and SNP sites significantly associated with traits were identified and within the correlation interval. Screening candidate genes related to the research purpose; transcriptome detection under the conditions of aerobic, anaerobic and oxygen content conversion of 02428 and YZX two materials, combined with genome-wide association analysis results, analysis of differences in expression patterns of candidate genes. 【Result】 Seed viability, coleoptile phenotype and seedling rate showed extensive genetic variation among 200 materials. Among them, the variation of coleoptile length and viability index was the most abundant, and the coefficient of variation was the largest. At the same time, the results of correlation analysis showed that there was a significant positive correlation between the coleoptile length, viability index and the seedling rate. Through genome-wide association analysis, 8 sites significantly associated with the viability index and 15 sites significantly associated with the coleoptile length were identified. Based on the correlation of seed growth and development and stress resistance, six candidate genes related to viability index and seven candidate genes related to the coleoptile length were screened in the relevant interval. Further comparison of 13 genes in aerobic and anaerobic the expression patterns and expression changes under oxygen conversion conditions showed that the three genes Os02g0657000, Os03g0592500 and Os08g0380100 showed different expression patterns when the oxygen content changed, and the expression amount changed significantly, showing sensitivity to oxygen treatment. 【Conclusion】 Seed viability and coleoptile length were closely related to the rate of flooding and seedling emergence, which could be used as an important trait for screening flood-tolerant rice materials. Combining genome-wide association analysis, transcriptome analysis and gene expression pattern can improve the screening efficiency of candidate genes for hypoxia tolerance germination of rice seeds; flooding tolerance of rice seedlings may be regulated by genes related to stress and photosynthesis..

Genome-Wide Association Analysis of Tribenuron-Methyl Tolerance Related Traits in Brassica napus L. Under Germination

ZHOU QingYuan, WANG Qian, YE Sang, CUI MinSheng, LEI Wei, GAO HuanHuan, ZHAO YuFeng, XU XinFu, TANG ZhangLin, LI JiaNa, CUI Cui

Scientia Agricultura Sinica. 2019, 52(3): 399-413. doi:10.3864/j.issn.0578-1752.2019.03.002

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【Objective】 To investigate the effect of residual tribenuron-methyl in soil on seed germination, genome-wide association analysis (GWAS) of 52157 SNPs with genome-wide coverage was used to identify the candidate genes for the germinating traits of rapeseed under tribenuron-methyl stress. The results of this study may provide a theoretical basis for tribenuron-methyl tolerance in oilseed rape.【Method】 In the germination experiment, 241 rape varieties (lines) were treated with tribenuron-methyl solution of 25 mg·L ^-1, and distilled water was added to the control. At the 7th day of germination, the phenotypic data including relative germination rate, relative root length and relative fresh weight were measured and calculated. Using the TASSEL software, tribenuron-methyl tolerance related traits were explored in B. napus under germination with a 60K Brassica Illumina ^? Infinium SNP array. Then, the structure of the population was analyzed by the software STRUCTURE, and the genetic relationship and LD attenuation were analyzed by the software TASSEL, respectively. In order to determine the optimal model for GWAS analysis of each trait, 6 models involved the general linear model and mixed linear model were used to analyze and compare the effects of group structure and relationship. The software TASSEL was employed to analyze the relative values of the 3 traits under the optimal model. Meanwhile, the candidate genes were predicted based on the LD interval sequence of the associated SNP locus. 【Result】 The population structure analysis showed the population could be divided into two subgroups, P1 with 94 materials and P2 with 147 materials. Meanwhile, the result of genetic relationship analysis showed that about 56.28% of the materials had no kinship relationship. In the optimal GWAS model (K+PCA), we found that 16 SNP loci significantly associated with 3 traits including relative root length, relative fresh weight and relative germination rate, and each locus explained phenotypic variations ranging from 9.42% to 13.14%. By analyzing the LD interval of the significant SNP locus and the corresponding interval sequence of Brassica napus, twenty-five candidate genes related to tribenuron-methyl tolerance were screened out in the LD interval of these significant SNP loci, in which nine of them belonged to cytochrome P450 gene families, five were involved in glutathione synthesis or metabolic processes, and two were multidrug-tolerance associated protein. At the same time, it was revealed that the gene ATGSTU19 significantly related to germination rate encodes glutathione transferase, which participates in the process of toxin decomposition and plays an important role in various stress responses. In addition, BnaC02g27690D was identified at relative root length and relative fresh weight. However, its function was not clear. 【Conclusion】 In this study, 16 SNP loci were detected to be significantly associated with tribenuron-methyl tolerance, and 25 candidate genes were screened out.

Mutagenic Effects of ⁶⁰Co-γ-rays on Two Species of Pennisetum Genus Forages

WU BingChao, TONG Lei, DU ZhaoChang, HU JiaLing, ZHANG Huan, CHEN Yi, LIU Wei, ZHANG XinQuan, HUANG LinKai

Scientia Agricultura Sinica. 2019, 52(3): 414-427. doi:10.3864/j.issn.0578-1752.2019.03.003

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【Objective】 Exploring the mutagenic effects of ⁶⁰Co-γ-rays on P. purpureum × P. americanurn. cv. Reyan No.4 and P. purpureum Schum. cv. Huanan and creating new germplasm, which aims to promote the process of Pennisetum breeding. 【Method】 Based on the pre-dose screening, using stems of the two species of Pennisetum as materials and irradiated by ⁶⁰Co-γ-rays and the dose was 30 Gy, the dose rate was 1 Gy·min ^-1. Then, the irradiated stems were planted in the field and conventional field cultivation management was performed. The survivor rate was counted one month later. After the plants to be survived mature, we randomly selected 30 individual plants from the two species Pennisetum and 7 morphological indicators of them were measured. Then, molecular markers were used to explore the effects of radiation on genetic variation. 【Result】 30 individual plants of the two species Pennisetum were selected randomly to measure the morphological indicators, respectively. The heights of 28 mutants, internodes of 21 mutants and leaf breadth of 17 mutants of Reyan No.4 have significant differences at 0.05 or 0.01 levels with the control. The heights of 20 mutants of Huanan have significant differences at 0.05 or 0.01 levels with the control, but there were no significant differences in other morphological indicators with the control. Most of the two species of Pennisetum mutants showed a decrease in plant height, and the biomass also decreased. However, we found that a mutant RY4-17 whose biomass is more than control because it has more tillers. The results of SSR molecular markers indicated that the average PIC of the 20 primers was 0.245 in the Reyan No.4 mutants, and a total of 83 bands were obtained, of which 52 bands were polymorphic. The GS between the mutants and the control was 0.67-0.89, the average was 0.81, the number of different sites was 9-27, with an average of 15.9. The UPGMA cluster showed that the distance between RY4-9, RY4-23 and control was the longest and indicated the mutation degree was greatest. In the Huanan mutants, the average PIC of the 20 primers was 0.394, a total of 81 bands were obtained, of which 65 bands were polymorphic. And the GS between the mutants and the control was 0.54-0.86, the average was 0.77, the number of different sites was 10-38, with an average of 18.8. The UPGMA cluster showed that the distance between HN-24 and control was the longest and indicated the mutation degree was greatest. 【Conclusion】 The appropriate dose of ⁶⁰Co-γ-rays radiation can significantly reduce the survival rate of the two species Pennisetum, and can effectively induce the mutations in the morphological and genetic. The method is an effective way to solve the lack of genetic resources caused by asexual reproduction of Pennisetum.

Effects of Coupling of Irrigation and Nitrogen Application as well as Planting Density on Photosynthesis and Dry Matter Accumulation Characteristics of Maize in Oasis Irrigated Areas

WEI TingBang, CHAI Qiang, WANG WeiMin, WANG JunQiang

Scientia Agricultura Sinica. 2019, 52(3): 428-444. doi:10.3864/j.issn.0578-1752.2019.03.004

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【Objective】 In oasis irrigation agricultural region, some problems has caused serious influenced of maize production, such as soil available water and nitrogen hunger, premature senescence and unreasonable planting density. To provide technical support for high and stable maize yield, the effects of different ratio of application irrigation and nitrogen and planting density on photosynthesis, dry matter accumulation characteristics and maize yield were studied. 【Method】 Photosynthetic ability, dry matter accumulation characteristics and yield were determined under two-years field experiment, which was carried out in Hexi Oasis irrigation region of Gansu province from 2016 to 2017. In this research, the cultivar “Xianyu335” was applied as research material. A split-split plot design was used as this experiment, with two irrigation application amount treatments (namely 4 050 m ³·hm ^-2 (W₁) and 3 720 m ³·hm ^-2 (W₂)) as the main plot, three nitrogen application amount treatments (namely 0 (N₀), 300 kg·hm ^-2(N₁) and 450 kg·hm ^-2 (N₂)) as the split plot, and three plant densities (namely 7.5×10 ⁴ plant/hm ²(D₁), 9.75×10 ⁴ plant/hm ²(D₂) and 1.2×10 ⁵ plant/hm ²(D₃)) as the split-split plot. 【Result】 Nitrogen fertilizer application and planting density had significant influence on photosynthetic rate, maximum dry matter accumulation rate, emergence days of maximum dry matter accumulation rate, dry matter accumulation amount, grain yield, water use efficiency and nitrogen fertilizer use rate in growth stages of maize. The coupling of irrigation and nitrogen fertilizer management increased photosynthesis, the highest dry matter accumulation rate and advanced the days of emergence of the highest dry matter accumulation rate, and enhanced dry matter accumulation amount and grain yield in growth stages of maize. Under the reduced 20% irrigation and the level of higher nitrogen application in growth stages of maize, compared with the low planting density and high planting density treatments, the photosynthetic rate under the medium planting density treatment was increased by 17.31% and 11.43%, respectively. While, compared with the low planting density treatment, the maximum dry matter accumulation rate and days of emergence of the highest dry matter accumulation rate under the treatment with the high planting density and medium planting density was increased by 21.07% and 7.52%, respectively, and advanced by 6.7, 4.1 days, respectively, meanwhile, the dry matter accumulation of the high planting density treatment was increased by 4.27% and 10.59%, respectively; Compared with the low planting density treatment and the high planting density treatment, the grain yield, water use efficiency and nitrogen fertilizer use rate of maize with the medium planting density treatment was increased by 24.2%, 11.4%, 29.9% and 29.2%, 18.4%, 13.8%, respectively. Under the reduced 20% irrigation and same planting density treatment in growth stages of maize, compared with medium nitrogen application treatment and no nitrogen application treatment, the photosynthetic rate, the dry matter accumulation and grain yield of maize under the treatment with high nitrogen application treatment was increased by 7.34%, 11.63%, 14.63% and 49.54%, 44.53%, 69.03%, under the medium planting density treatment, respectively; Compared with medium nitrogen application treatment and no nitrogen application treatment, the maximum dry matter accumulation rate and days of emergence of the highest dry matter accumulation rate of maize with the high nitrogen application treatment was increased by 19.07% and 54.35% and advanced by 3.9 and 6.8 days under the high planting density treatment, respectively. Compared with no nitrogen application treatment, nitrogen fertilizer use rate of maize with the high nitrogen application treatment was increased by 24.50%. The facts showed that the coupling of reduced 20% irrigation and high nitrogen application had regulated dry matter accumulation, grain yield with the improvement of photosynthesis, dry matter accumulation rate, water use efficiency, nitrogen fertilizer use rate and extending the duration of dry matter accumulation. 【Conclusion】 The treatment with application coupling of irrigation and nitrogen (i.e. reduced 20% irrigation amount during growth 3 720 m ³·hm ^-2(W₂) and N application with 450 kg·hm ^-2 at growth stage and medium density of 9.75×10 ⁴ plant/hm ² at growth stage of maize) could be considered as the best feasible cultivation pattern management, which could provide technical guidance for further exploring high yield and efficient cultivation of close planting maize in Oasis irrigation region.

A Method of Ecological Suitability Evaluation and Its Application for Maize Planted in Mountain Farmland Based on GIS (Case Study: Xundian County)

LI Chao, LI WenFeng, ZHAO Yao, SHANG JingMin

Scientia Agricultura Sinica. 2019, 52(3): 445-454. doi:10.3864/j.issn.0578-1752.2019.03.005

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【Objective】 Crop suitability evaluation is an important means for production zoning. This paper developed a new evaluation model of the ecological suitability for maize planted in mountain farmland, according to climatic, soil and topography condition. 【Method】 An evaluation index system of maize ecological suitability were selected after a systematic and comparative analysis of literature reviews, and 18 eco-environment factors were involved in the system. A climate model was established by the method of agricultural modeling based on the climatic conditions of maize growth period and ecological efficiency. The membership function method was used to calculate the suitability index for numerical and conceptual indicator variables, respectively. Expert scoring and analytic hierarchy process were used to determine the weight of each factor. Combining the weights and evaluation function, a new evaluation model was constructed to evaluate the suitability of climate, soil nutrient, site conditions, land management, and comprehensive ecological suitability. According the stereoscopic character of mountain farmland, evaluation units were divided by land using, soil type, and administrative division. The values of 18 indicators were calculated by GIS spatial analysis and attached into evaluation unites. Using the evaluation model and spatial data, the maize ecological suitability was evaluated for each class respectively or comprehensively. 【Result】 This method was used to evaluate maize ecological suitability in Xundian county, where the cultivated land was divided into 8 415 evaluation units. The suitable and high suitable area in climatic condition, soil nutrient, site condition, land management accounted for 58%, 86%, 42%, and 90%, respectively. The suitable and higher suitable area of maize planting accounted for 50.6% and 35.4%, respectively, which mainly distributed in the middle-southeast low-middle hilly area, and some in the central and northern Jinsha River valleys and western valley trough areas. The barely suitable and unsuitable area accounted for 9.4% and 4.6%, which mainly distributed in the northwest and some in the west of the central part. 【Conclusion】 This method was able to response the climatic difference during maize growth period and the stereoscopic character of mountain farmland. The suitability area distributed as fragments. The results were consistent with the regional situation basically. The climate and terrain were primary limit factors for the ecological suitability of maize in the region.

Fungal Community Structure of Cotton-Field Soil Under Different Incidences of Cotton Verticillium Wilt

LIU HaiYang, WANG Wei, ZHANG RenFu, RAXIDA ·ABDURAHMAN, YAO Ju

Scientia Agricultura Sinica. 2019, 52(3): 455-465. doi:10.3864/j.issn.0578-1752.2019.03.006

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【Objective】 Fungus is an important part of soil microbial system, which can obviously indicate the change of soil environment. The objective of this study is to analyze the characteristics of fungal communities in cotton-field soil with different incidences of Verticillium wilt, determine the effect of Verticillium dahliae on the diversity and community structures of fungi in cotton fields, and to reveal the ecological function of fungi community in soil during the occurrence of Verticillium wilt.【Method】 Cotton fields with different incidences of Verticillium wilt in Aksu and Shihezi, and artificially inoculated cotton field in Korla were chosen as research objects. Six soil samples collected from serious diseased fields in Aksu (AD), Korla (KD), Shihezi (SD) and their controls were tested, respectively. Illumina Hiseq high-throughput sequencing technique was used to study the diversity and community structure of fungi in soil. The correlation between fungal community structure and soil nutrients was clarified with redundancy analysis (RDA).【Result】 At the similarity level of 97%, the OTU number, Chao1 and Ace richness index of fungi in AD and SD samples were higher than those of ACK and SCK samples, while the Simpson index was lower than that of control. There was no significant difference in OTU number, Chao1 and Ace richness index and Simpson index between artificially inoculated KD and control KCK samples. NMDS analysis showed that the soil samples of AD and SD had spatial tendency first and then temporal tendency, while the soil samples in Korla had temporal tendency first and then spatial tendency. In terms of community composition, at the phylum level, the abundance of Ascomycota in soil was dominant, followed by Basidiomycota and Mortierellomycota. The abundance differences of the three phylum groups between KD and KCK samples and between SD and SCK samples were relatively small, while those between AD and ACK samples were relatively larger. At the genus level, Sporobolomyces had the highest abundance, and the abundances of both Sporobolomyces and Mortierella were higher than those of the control in the soils of seriously diseased field in different regions, but Wardomyces was lower than that of the control. In addition, the abundance of Pyrenochaetopsis, Microdochium and Fusarium in AD samples was lower than that of ACK samples, while the abundance of these three genera in SD samples was higher than that of SCK samples. The significant difference analysis among groups indicated that the significant difference markers in Korla and Shihezi soils were mainly concentrated in the seriously diseased fields, while in Aksu soils they were mainly concentrated in disease-free fields. Correlation and RDA analysis showed that soil organic matter and total nitrogen content were positively correlated with OTU number and abundance of fungi, but had low correlation with Simpson index. The pH, total phosphorus and total potassium were positively correlated with Simpson index, while total salt was negatively correlated with Simpson index.【Conclusion】 The OTU number and abundance of fungi in the soil of natural seriously diseased cotton fields are higher than those in the control, but the diversity of fungi is low. In the short term, artificial inoculation does not have significant effects on the abundance, diversity and community structure of the fungi in the soil. The diversity, abundance and composition of fungi in soil are significantly affected by the indexes of organic matter, total nitrogen and salt content. The sampling period also has significant effects on the community structure of fungi in soil.

Characteristics, Developmental Expression and RNAi Effect Analysis of a Novel Trehalose-6-Phosphate Synthase Gene in Nilaparvata lugens

TANG Bin,SHEN QiDa,ZENG BoPing,XIAO ZhongJiu,QIU LingYu,PAN BiYing,LI Kun,ZHANG DaoWei

Scientia Agricultura Sinica. 2019, 52(3): 466-477. doi:10.3864/j.issn.0578-1752.2019.03.007

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【Background】 Insect trehalose-6-phosphate synthase (TPS) is the main gene for insect trehalose synthesis. Most insects possess one trehalose-6-phosphate synthase gene, and some insects have one trehalose-6-phosphate phosphatase (TPP) gene. Previous studies have found that there are two TPS genes in the brown planthopper (Nilaparvata lugens) and their functional studies have shown that TPS can not only regulate trehalose metabolism, but also mediate trehalase regulation of chitin synthesis and degradation pathways, and control insect molting process.【Objective】 A novel TPS was obtained by the transcriptome sequencing of N. lugens. The objective of this study is to detect the expression of the gene in different developmental stages of N. lugens, and to explore the difference between the function of the gene and the two previously discovered TPS genes.【Method】 The full-length cDNA sequence of the novel TPS was obtained by cloning technique. After correct verification, the primary, secondary, and tertiary structures of the protein were obtained. The protein structure and alignment of TPS were analyzed with other insects. Finally, qRT-PCR was used to determine the expression of three different TPS genes at different development stages of N. lugens, and RNA interference (RNAi) was used to inhibit the expression of TPS3.【Result】 Based on the previous study, this novel TPS was cloned and named as TPS3. The open reading frame of TPS3 is 2 352 bp, encoding 783 amino acids. The predicted molecular weight of the protein is 88.9 kD and the isoelectric point is 5.47, with a hydrophilic structure. Bioinformatics analysis showed that the three TPS proteins of N. lugens had high homology, with two conserved domains of TPS and TPP and other characteristic sequences, and the proportion of α-helix, β-sheet, and random curl was similar. The relative expression levels of three TPS genes in different developmental stages of N. lugens were different. The relative expression level of TPS1 gradually increased from 0 h of 4th instar to the highest level at the adult stage. The relative expression level of TPS2 increased obviously from the end of 4th instar and was higher in the whole 5th instar. The expression of TPS3 was relatively higher at the end of the 5th instar and the early stage of adult. The relative expression level of the interfered gene significantly decreased after 48 hours of single interference with TPS3. The dsTPS3 could effectively inhibit the expression of TPS3.【Conclusion】A novel TPS (TPS3) was found in N. lugens, which has high homology with TPS1 and TPS2 reported in N. lugens. The results of expression at different developmental stages showed that the three TPS genes performed different functions during development. RNAi could effectively inhibit the expression of TPS3 and lead to molting and wing deformity.

Spatio-Temporal Variability of Soil Available Nutrients Based on Remote Sensing and Crop Model

FANG HuiTing,MENG JiHua,CHENG ZhiQiang

Scientia Agricultura Sinica. 2019, 52(3): 478-490. doi:10.3864/j.issn.0578-1752.2019.03.008

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【Objective】 The spatio-temporal variability of soil available nutrients in Shuangshan farm during 2012-2016 was studied under uniform fertilization mode. The influence of human factors (such as fertilization management and crop rotation model) and natural factors (such as meteorology and topography) on the changes of available nutrients were analyzed, which could be used to provide references for soil available nutrients management and crop variable fertilization.【Method】 The time series satellite HJ-1 CCD imagery and the WOFOST crop model were selected to retrieve soil available nutrients. Based on the above soil available nutrients data, spatio-temporal variability of soil available nutrients analysis of available nutrients on different time scales (interannual and within-year) and different spatial scales (farm scale and field scale) was carried out. The hierarchical maps of soil available nutrients were used to qualitatively analyze the spatial variability of nutrients in five years. The specific statistical parameters were used to quantitatively analyze the average content and variability of soil available nutrients. The linear regression was used to analyze the relationship of variation and initial content of available nutrients. And the temporal variation characteristics of available nutrients were analyzed by the change curve of available nutrients. 【Result】 The average contents of available nitrogen (AN), available phosphorus (AP) and available potassium (AK) in the farm were not changed obviously from 2012 to 2016. The high and low values of available nutrients were all close to the middle value, which were concentrated at 280-360 mg·kg ^-1, 38-42 mg·kg ^-1and 160-200 mg·kg ^-1, respectively. And the area of these three parts increased by 18.5%, 23.1% and 23.8%, respectively, which showed uniform characteristics as a whole. The coefficient of variation of AN, AP, and AK changed from 0.314, 0.112, and 0.257 in 2012 to 0.131, 0.034, and 0.098 in 2016, respectively. And the spatial heterogeneity of available nutrients distributions was weakened. The variation of AN and AP were negatively correlated with the initial values in 2012, and the determination coefficient were 0.839 and 0.882, respectively. And the determination coefficient of AK was 0.569, its weak correlation was related to the instability of AK in the soil itself. The nutrients change characteristics of adjacent field indicated that the soil available nutrients on the field scales also showed obvious uniform characteristics. Crop rotation mode was the main factor affecting the difference of nutrients change between fields. For the field #1 and field #2 with the opposite rotation mode, artificial fertilization determined the general trend of nutrients change in the field. For leguminous plants, nitrogen fixation had a significant effect on the content of soil available nitrogen. The increase in temperature would promote the absorption of nutrients by crops to a certain extent, but this effect was not enough to change the general trend of nutrient changes. Soil leaching played a decisive role in the spatial variability of nutrients, especially for stronger precipitation. The effect of precipitation on nutrients spatial variability was more pronounced in areas with large topography variation.【Conclusion】 Farmland fertilization management and crop rotations were the dominant factors in the change of soil available nutrients, followed by topographic and climatic factors. The leaching of rainwater would lead to the loss and decline of soil available nutrients, which was more obvious in the area with larger topography. The amount of change in available nutrients was significantly related to the initial nutrients content. The increase of temperature would accelerate the decrease of available nutrients in soil, and its influence was less than that of precipitation. The above rules could be included in the prediction model of available nutrients, and different weights were assigned to these influencing factors to construct the prediction model, to achieve real-time dynamic monitoring of the variation of soil available nutrients in the inter-annual and growing seasons.

Effects of Subsoiling and Irrigation Frequency on Water Saving and Yield Increasing of Winter Wheat and Summer Maize in the Huang-Huai-Hai Plain

QIANG XiaoMan,ZHANG Kai,MI ZhaoRong,LIU ZhanDong,WANG WanNing,SUN JingSheng

Scientia Agricultura Sinica. 2019, 52(3): 491-502. doi:10.3864/j.issn.0578-1752.2019.03.009

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【Objective】 The effects of interactions between subsoiling and irrigation frequency on crop yield and water productivity of winter wheat and summer maize were investigated to optimize tillage practices in the Huang-Huai-Hai Plain.【Method】 Considering different tillage methods and irrigation times, a field experiment was carried out with five treatments, including autumn subsoiling with two irrigation applications during winter wheat growth period (QS-2), autumn subsoiling with three irrigations applications during winter wheat growth period (QS-3), summer subsoiling with two irrigations applications during winter wheat growth period (XS-2), summer subsoiling with three irrigations applications during winter wheat growth period (XS-3) and control (CK). The effects of subsoiling and irrigation times on soil physical properties, plant growth and development, yield, total output, and water productivity of winter wheat and summer maize were investigated. 【Result】 Subsoiling and irrigation times had significant impacts on soil bulk density, soil compaction, soil water storage, total output and water productivity. After subsoiling, the bulk density decreased significantly in topsoil 40 cm at the first year and in topsoil 20 cm at the second year under all QS-2, XS-2 and XS-3 treatments, compared with CK treatment. The decline of soil compaction was remarkable in the first year, but inapparent in the second year. After autumn subsoiling, the average soil water storage of QS-2 treatment increased by 18.14% compared with CK, and the QS-3 treatment was the second. While, in the second year after summer subsoiling, the XS-2 and XS-3 treatments were significantly higher than CK by 24.7% and 25.6%, respectively. Compared with CK treatment, aboveground biomass of winter wheat increased by 19.29% for QS-2 and 27.06% for QS-3 treatment, respectively, for the first year, while there was slight increase for the second year. This indicated that the improvement of winter wheat growth and development by autumn subsoiling was pronounced in the first year but weak in the second year. However, the leaf area index and aboveground biomass of XS-2 and XS-3 treatments were increased significantly, and this demonstrated that summer subsoiling could improve the winter wheat growth and development in the second year. The total output and water productivity of winter wheat and summer maize rotation for QS-2 treatment were improved by 27.21% and 23.51% in the first year, respectively, and 19.54% and 18.84% in the second year, respectively, meanwhile, there were significant improvement for XS-2 and XS-3 treatment in the second year. The increase of total output and water productivity were 18.50% and 17.65% for XS-2, respectively, and 19.57% and 15.35% for XS-3 treatment, respectively.【Conclusion】 It was concluded that autumn subsoiling before winter wheat seeding could facilitate the reduction of soil bulk density and compaction, increase of soil storage capacity, and improvement of total output and water productivity of winter wheat and summer maize rotation in the Huang-Huai-Hai Plain. It was suggestion that the appropriate tillage practice in the Huang-Huai-Hai Plain was autumn subsoiling with two irrigation applications during winter wheat growth stage.

Molecular Cloning and Functional Characterization of VcNAC072 Reveals Its Involvement in Anthocyanin Accumulation in Blueberry

SONG Yang,LIU HongDi,WANG HaiBo,ZHANG HongJun,LIU FengZhi

Scientia Agricultura Sinica. 2019, 52(3): 503-511. doi:10.3864/j.issn.0578-1752.2019.03.010

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【Objective】 The objective of this study was to isolate a transcription factor VcNAC072 (NAM, ATAF1/2, CUC2) from blueberry by PCR technology and studying its expression, and to identify its role in anthocyanin biosynthesis. This study laid the foundation for further study of the molecular mechanism of VcNAC072 affecting anthocyanin biosynthesis in blueberry. 【Method】 The blueberry VcNAC072 gene was cloned by PCR technology from the fruits of blueberry (Vaccinium corymbosum ‘Duke’). The transgenic Arabidopsis thaliana were generated via Agrobacterium-mediated transformation. The differences in the anthocyanin accumulation were compared between transgenic and wild-type Arabidopsis. The yeast one-hybrid (Y1H) and transient expression assays were carried out to test the transcriptional regulation of MYB transcription factor AtPAP1 by VcNAC072. 【Result】 A blueberry VcNAC072 was cloned from blueberry. Sequence analysis showed that the coding domain sequence (CDS) of VcNAC072 was 1 032 bp, which encoded 343 amino acids. Protein structure analysis showed that VcNAC072 contained a NAC domain. Expression analysis showed that VcNAC072 was expressed at different developmental stages of the blueberry fruits. However, the expression levels varied, with the highest expression level in pink fruits and blue fruits and the relatively low transcript levels in green fruits. The content of anthocyanin in fruits was increased with the elevation of relative expression of VcNAC072. The sequence of AtPAP1 promoter was analyzed and a NAC binding motif was found. The VcNAC072 protein could interact with the promoter of AtPAP1. Moreover, the VcNAC072 could induce the expression of AtPAP1 and favorably contributed to anthocyanin accumulation in seeds of transgenic Arabidopsis. 【Conclusion】 It was speculated that VcNAC072 up-regulated anthocyanin accumulation in fruits of blueberry.

Using Chlorine Dioxide Treatment to Promote Wound Healing of Postharvest Muskmelon Fruit

ZHENG XiaoYuan, WANG TiaoLan, ZHANG JingRong, JIANG Hong, WANG Bin, BI Yang

Scientia Agricultura Sinica. 2019, 52(3): 512-520. doi:10.3864/j.issn.0578-1752.2019.03.011

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【Objective】 The aims of this study were to investigate effect of chlorine dioxide (ClO₂) treatment on the wound healing of harvested muskmelons and its mechanism, providing methods and theoretical basis for wound healing of postharvest muskmelon fruit.【Method】 The muskmelon fruit ‘cv. Manao’ was used as material. After artificially wounded, fruits were dipped with ClO₂ at 25 mg?L ^-1 for 10 min, and the treated fruit and control were wound healed at ambient temperature in dark. The weight loss of fruit and the disease index of Trichotechium roseum inoculated fruit were measured during healing. The accumulation of suberin poly phenolic, suberin poly aliphatic and lignin at the wounded sites of fruit were observed by Toluidin blue O-neutral red staining and phloroglucinol-HCl staining method, and the amount of accumulation of the three compositions were measured by IS Capture image software. Moreover, the color values of wounded surface were measured. The enzyme activities of phenylpropanoid metabolism and changes of peroxidase and polyphenol oxidase enzyme activities were analyzed during the fruit wound healing stage. 【Result】 The weight loss of wounded fruit and the disease index of inoculated fruit were significantly reduced by ClO₂ treatment. The weight loss of treated fruit was 10.3% lower than that of control after 7 days of healing. Wounded fruit were inoculated by Trichotechium roseum at different wound healing periods. After one week cultivated, the disease index of the treated fruit was significantly lower than that of control, which was 56.9% lower at 7 days of healing. The ClO₂ treatment significantly promoted the accumulation of suberin poly phenolic, suberin poly aliphatic and lignin. The treated fruit were significantly higher than that of control at the mid and late stage of healing. After 7 days of healing, the thickness of suberin poly phenolic cell layers, suberin poly aliphatic and lignin cell layers of treated fruit was 25.3%, 77.7% and 35.5% higher than that of control, respectively. Compared with the control, the L* value of wounded surface in the treated fruit was significantly lower and b* value was significantly higher during healing. The L* value of the treated fruit was 6.1% lower than that of control after 5 days of healing. And the b* value of the treated fruit was 17.8% higher than that of control after 3 days of healing. The ClO₂ treatments increased enzymes activities of phenylalanine ammonia-lyase, peroxidase and polyphenol oxidase at wounded sites of fruit, which were 34.3%, 80.5% and 15.7% higher than that of control after 7 days of healing, respectively. Meanwhile, the treatment also improved the accumulation of total phenols, flavonoids and lignin at wounded sites, which were 14.7%, 16.8%, and 15.6% higher than that of control after 7 days of healing, respectively.【Conclusion】 ClO₂ treatment effectively promoted wound healing of harvested muskmelons by eliciting the phenylpropanoid metabolism. In addition, it also increased the enzymes activities of peroxidase and polyphenol oxidase, and promoted accumulation of suberin and lignin at wounded sites.

CRISPR Locus Analysis of Lactobacillus casei

YANG Lan,YANG Yang,LI WeiXun,OBAROAKPO JOY,PANG XiaoYang,LÜ JiaPing

Scientia Agricultura Sinica. 2019, 52(3): 521-529. doi:10.3864/j.issn.0578-1752.2019.03.012

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【Objective】 The application of the CRISPR/Cas9 gene editing system based on Streptococcus pyogenes spCas9 has restriction on lactic acid bacteria at present. It is urgent to develop a suitable gene editing system for lactic acid bacteria. In this study, we analysed the CRISPR system of Lactobacillus casei in depth, and then predicted the PAM sequence to activate its Cas9 protein. Our study provided the experimental foundation for the development of the CRISPR/lcCas9 gene editing system for lactic acid bacteria 【Method】 In this study, six strains of whole genome-sequenced L. casei were used as research object. Bioinformatics was used to analyze the CRISPR system. Cas protein structure, CRISPR system and homology of space were analysed. At the end, the second structure of the CRISPR repeat and PAM sequence recognized by Cas9 protein were predicted. 【Result】 The CRISPR system of L. casei had similar structures characteristic of Cas9 protein, and the Cas gene were conserved. It was predicted that the tracrRNA was located between Cas9 and Cas1, and the repeat sequence could form a secondary structure with a stem length of seven bases. According to the sequence characteristics of CRISPR spacers, six Lactobacillus casei could be divided into three genotypes. Then the spacer sequences were blasted one by one. The results showed that the six spacers aligned 14 original source sequences with different origins, and these spacer sequences were all derived from different plasmids. The PAM sequence recognized by L. casei lcCas9 protein preferred T/C, A/C at the 1 ^st and 3 ^rd bases. The 2 ^nd and 4 ^th bases had greater preferences for G and A.【Conclusion】 The CRISPR system of six strains of L. casei were all type-IIA. Consequently, the Cas gene and repeat sequences were highly conserved. The DR sequence formed a stable secondary structure, while TGMA as a PAM sequence was effectively identified by the Cas9 proetein of L. casei.

Optimizing the Electroporation Condition of Porcine Fetal Fibroblasts for Large Plasmid

ZHONG CuiLi,LI GuoLing,WANG HaoQiang,MO JianXin,QUAN Rong,ZHANG XianWei,LI ZiCong,WU ZhenFang,GU Ting,CAI GengYuan

Scientia Agricultura Sinica. 2019, 52(3): 530-538. doi:10.3864/j.issn.0578-1752.2019.03.013

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【Background】 With the development of biotechnology, the physiological mechanisms and biological functions of research are becoming more and more complex, and improving the transfection efficiency of large vectors is of great significance for multi-gene co-expression systems, genome editing, and transgenic breeding. In transgenic breeding, the transgenic vectors is relatively large, and the efficiency of generating transgenic animals is also attributed to the transfection efficiency of porcine fetal fibroblasts (PFFs). 【Objective】 Therefore, this study mainly compared the electroporation efficiency of three electroporation apparatus ECM ^? 830/NEPA 21/Nucleofector ^TM 2b on various parameters, plasmid dosage and topology, to explore the optimal electroporation condition of large vector in PFFs. 【Method】 We transfected a 26 kb plasmid, namely pPXAT-EGFP, into the PFFs, and then the electroporation efficiencies of various parameters of three electroporation apparatus ECM? 830/NEPA 21/Nucleofector ^? 2b, and the dosage and topological structure of the plasmid by the flow cytometry were compared. 【Result】 By comparing the transfection efficiency of different transfection parameters, the results showed that the highest transfection efficiency of NEPA 21 was 13.24%±1.63% at pulse voltage 300 V, pulse length 1 ms, pulse interval 50 ms, pulse number 3 times, and the optimal electrical rotation parameter of Nucleofector ^TM 2b was U-023, whose transfection efficiency was 46.36%±3.95%. In addition, the transfection efficiencies of 6, 8, 10 and 12 μg 26 kb supercoiled plasmids were compared under the optimal electroporation parameters, and the results showed that the optimal plasmid dosage for ECM? 830 and Nucleofector ^TM 2b transfected PFFs was 12 μg with 8.44% ± 0.90% efficiency (transfection parameters: pulse voltage 300 V, pulse length 1 ms, pulse number 3 times) and 14.63% ± 3.21% (U-023), while the NEPA 21 achieved the highest efficiency of 6.09% ± 0.72% with 10 μg plasmid. Finally, we compared the transfection efficiency of different quality topologies and found that the transfection efficiency of linearized plasmids was low, only 34.96%-48.39% of the supercoiled plasmids. 【Conclusion】 Therefore, the optimal electroporation condition of PFFs by Nucleofector ^? 2b was U-023 procedure, 12 μg supercoiled plasmid; NEPA 21 was pulse voltage 200 V, pulse length 3 ms, pulse interval 50 ms, pulse number 3 times, and 10 μg supercoiled plasmid; ECM? 830 was transfected with 12 μg supercoiled plasmid at pulse voltage 300 V, pulse length 1 ms, and pulse number 3 times to obtain the highest transfection efficiency. Comprehensive comparison of the above three kinds of electroporation apparatus, the optimum for transfecting PFFs with 26 kb large carrier was Nucleofector ^? 2b.

Establishment of a Prediction Model of Metabolizable Protein of Concentrate for Mutton Sheep

FU LiXia,MA Tao,DIAO QiYu,CHENG ShuRu,SONG YaZhe,SUN ZhuoLin

Scientia Agricultura Sinica. 2019, 52(3): 539-549. doi:10.3864/j.issn.0578-1752.2019.03.014

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【Objective】 The aim of this study was to establish a predictive model of metabolizable protein (MP) of concentrates, which is commonly used in feedstuffs of sheep by nutrient or nutrient digestibility. 【Method】 Six 14-month-old Dorper (♂) × thin-tailed Han sheep (♀) sheep with an average body weight of (49.27±3.12) kg fitted with a permanent rumen fistula were selected and used in testing effective degradation rate, rumen undegraded dietary protein (UDP) and intestinal digestibility of UDP by nylon bag method and three-step modified in vitro method. Ten healthy Dorper × thin-tailed Han ram with an average body weight of（47.43±4.41）kg were selected and used in 11 treatment groups including one basic diet group and 10 experimental groups（The Chinese wildrye hay, corn and soybean meal of basic diet were replaced by sorghum, corn, barley, wheat, oat, rapeseed peanut, cottonseed, soybean and DDGS.), respectively. Each period lasted for 20 d (15 d for adaptation and 5 d for trial period). The experimental sheep were prefixed with ear numbers, dewormed with ivermectin, and feed a single column. Due to the differences in the nutrient composition of each group of feeding foods, the amount of feeding in the lowest group was observed and determined during the adaptation as the limit of feeding, fed twice a day, at 8:00 and 16:30, respectively. Feed 600 g, free drinking water. Each ram is a replicate and all rams were used to determine the apparent digestibility of nutrients and microbial synthetic protein (MCP) using the urinary purine derivative method. The MP predictive model was established using proximal analysis of nutrient contents or nutrient digestibility. Using NLIN program in SAS 9.1 to calculate a, b, c values and linear regression and multivariate regression program analysis, MP estimation model was established, and the single factor variance analysis(one-way ANOVA, LSD) was significantly tested. 【Result】 The results showed that the rumen digestibility and digestion rate of CP in different concentrates were different, and CP degradability and intestinal digestibility of UDP of high protein diet were higher. The effective degradation rate of CP rumen in 10 kinds of feed ranged from 43.71% to 60.87%, and intestinal digestibility of UDP ranged from 80.10% to 92.86%. The effective degradation rate of rumen in oat feed was significantly higher than that of other feeds (P＜0.001), while intestinal digestibility of UDP was significantly lower than that of other feeds (P＜0.001). The diets had different composition and apparent digestibility of different nutrients. The digestion and absorption sites of dietary protein did not affect the apparent digestibility of nutrients. The ratio of MP to DP of 10 feeds in this study ranged from 50.96% to 62.33%, The digestible protein (DP, %) prediction model established by dietary CP (%) content was：DP=0.895×CP-2.663 (R ²=0.994, n=10, P＜0.001); The MP (g·kg ^-1 DM) prediction model established by nutrient contents (%) and apparent nutrient digestibility (%) were: MP=5.323×CP-14.374 (R ²=0.994, n=10, P＜0.001) and MP=5.899×DP+2.077 (R ²=0.984, n=10, P＜0.001).【Conclusion】Digestible protein had a strong relationship with crude protein in diet. The nutrient content and nutrient digestibility in diets were correlated with the presence of MP, and the MP values of concentrate feed could be estimated more accurately by the nutrient and nutrient digestibility in diets.

The Upper Limit Temperature of Thermoneutral Zone Estimated by the Changes of Temperature and Respiration Rate of the Broilers

YANG YuYan,WANG XueJie,ZHANG MinHong,FENG JingHai

Scientia Agricultura Sinica. 2019, 52(3): 550-557. doi:10.3864/j.issn.0578-1752.2019.03.015

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【Objective】 The present study was conducted to measure the variations of surface temperature (ST), core temperature (CT) and respiratory rate (RR) of broilers with increasing ambient temperature (AT), and analyze these data with a broken-line model to determine the inflection point temperature (IPT, the certain AT above which the body temperature or RR of the broilers started to change). 【Method】 Ten AA broilers (21 days old) were raised in one controlled climate chamber. The AT of chamber was increased gradually by one degree per 0.5 h from 18℃ to 33℃, and then gradually decreased to 20℃. The CT and ST of broilers, as well as the AT in the chamber were recorded at 10 min intervals using mini temperature data loggers. The experiment was repeated three times on three days. 【Result】 The IPT based on ST (IPT_ST) for three consecutive days were 21.18, 21.09 and 21.13℃, average 21.13℃. The variation coefficients of IPT_ST between individual broilers was 6.13, 6.15 and 5.64 for three measurements, the variation coefficient of IPT_ST between three measurements was 0.52% on average, indicating that the method of estimating IPT_ST was better repeatable. The IPT based on CT (IPT_CT) for three consecutive days were 27.80, 27.98 and 27.67℃, with an average of 27.82℃. The variation coefficients of IPT_CT between individual broilers was 2.82, 2.75, 2.78 for three measurements, the variation coefficient of IPT_ST between three measurements was 0.90% on average, indicating that the method of estimating IPT_CT was better repeatable. The IPT based on RR (IPT_RR) for three consecutive days were 28.42, 29.52 and 29.25℃, with an average of 29.06℃. Since the panting of broilers is intermittent, the respiratory of broilers under high temperature maybe normal during the period of RR measurement (only 1 min per chick), which maybe result in an under-estimated the RR, and an over-estimated IPT_RR of some broilers. 【Conclusion】 According to the definition of the thermal neutral zone, the upper limit temperature of the thermal neutral zone of 3-4 weeks old broilers should be lower than IPT_CT (27.82℃), and the upper limit temperature of thermal comfort zone is IPT_ST(21.13℃).

Screening and Identification of Proteins Interacting with Bombyx mori IAP and Their Effects on BmNPV Proliferation

CHEN Peng,BAO XiYan,KANG TaoTao,DONG ZhanQi,ZHU Yan,PAN MinHui,LU Cheng

Scientia Agricultura Sinica. 2019, 52(3): 558-567. doi:10.3864/j.issn.0578-1752.2019.03.016

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【Objective】 As an important part of insect immune response, apoptosis plays an important role in the interaction between virus and host. The study of apoptosis-related genes is of great value in elucidating their roles in the process of virus infection. The objective of this study is to screen the interaction proteins of Bombyx mori inhibitor of apoptosis proteins (BmIAP), verify the regulatory relationships between them and Bmiap in the process of B. mori nucleopolyhedrovirus (BmNPV) infection and their roles in the proliferation of BmNPV, and to provide a theoretical basis for exploring the molecular mechanism of the interaction between host and BmNPV.【Method】 The proteins interacting with BmIAP in the process of BmNPV infection in B. mori cells were screened by immunoprecipitation, and the specific differential bands were analyzed by LC-MS/MS. The obtained proteins were identified according to the molecular weight of the protein and bioinformatics method. The candidate gene was obtained by molecular cloning technique, and the domain of the candidate gene was predicted by SMART online tools and the multiple sequence alignment analysis was performed with BioEdit. Co-localization of BmIAP and candidate protein was verified by immunofluorescence assay, and their interaction was further verified by immunoprecipitation. The candidate gene was overexpressed and knocked out by eukaryotic expression and CRISPR/Cas9 gene editing system, respectively. The expression of corresponding genes was detected by qRT-PCR to determine the regulatory relationship between Bmiap and Bmpp5 in the process of BmNPV infection. Similarly, the expression of baculovirus Vp39 was detected after overexpression and knockout of Bmpp5 to determine the effect of Bmpp5 on the proliferation of BmNPV.【Result】 Seven host proteins and one BmNPV protein which may interact with BmIAP were obtained by immunoprecipitation and further analysis identified a candidate gene Bmpp5 associated with apoptosis. The open reading frame (ORD) of Bmpp5 is 1 473 bp, encoding 490 amino acids. The predicted molecular weight of BmPP5 is about 56 kD. It contains three TRP domains and one PP2Ac domain. It is highly conserved among insects. Immunofluorescence assay showed that BmIAP and BmPP5 were co-localized in cytoplasm, and the results of immunoprecipitation showed that they could interact with each other. In the process of BmNPV infection, after overexpression of Bmiap, the expression of Bmpp5 was significantly up-regulated, while after knockout of Bmiap, the expression of Bmpp5 was significantly down-regulated, suggesting that Bmiap could promote the expression of Bmpp5. Bmiap was significantly up-regulated after overexpression of Bmpp5, while Bmiap was significantly down-regulated after knockout of Bmpp5, suggesting that Bmpp5 could also promote the expression of Bmiap. Overexpression of Bmpp5 could promote the proliferation of BmNPV, and knockdown of Bmpp5 could inhibit the proliferation of BmNPV, indicating that the expression of Bmpp5 was conducive to the proliferation of BmNPV. 【Conclusion】 A protein BmPP5, which interacts with BmIAP was identified and highly conserved in insects. In the process of BmNPV infection, Bmiap and Bmpp5 can promote each other. It is also proved that Bmpp5 can promote the replication and proliferation of BmNPV.

Genetic Diversity of the Prunus salicina L. from Different Sources and Their Related Species

WEI Xiao,ZHANG QiuPing,LIU Ning,ZHANG YuPing,XU Ming,LIU Shuo,ZHANG YuJun,MA XiaoXue,LIU WeiSheng

Scientia Agricultura Sinica. 2019, 52(3): 568-578. doi:10.3864/j.issn.0578-1752.2019.03.017

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【Objective】 There are abundant Japanese plums (Prunus salicina L.) germplasm resources in China, which are distributed widely in geography. The better understanding of the diversity, the genetic structure and the relationship between sympatric related species, can be helpful to clarify the process of domestication of the cultivated groups of plum and the role of the related species, also further contribute to the in-depth exploration of local resources and enhance the fruit quality in breeding. 【Method】 The 22 pairs of SSR markers covering the entire genome were used to scan 48 samples, including 38 accessions of P. salicina from different sources and 10 accessions of the variation types or related species, by high-throughput fluorescence capillary electrophoresis platform. The polymorphism of 22 SSR loci and genetic diversity of 48 samples were evaluated via the software GenAlEx 6.41, and the dendrogram of these accessions was constructed by using the NTSYS-pc Version 2.1 program. The STRUCTURE 2.2 software based on Bayesian clustering method was used to analyze the genetic mixture of samples and to perform an assignment test on the studied individuals. 【Result】 The detected alleles of 22 SSR primers ranged from 3 to 21, with an average of 13.54 alleles for each locus. A total of 298 alleles were detected in these accessions, 51.8% of which were rare alleles. The values of average effective allele (Ne), average Shannon's diversity index (I), observation heterozygosity (Ho) and expectation heterozygosity (He) indicated that the diversity was the highest in the southern population, followed by the northeast population, which also indicated that the diversity of the Prunus simonii was lower than that of northern China. The analysis of molecular variance (AMOVA) showed that 69% of the diversity in P. salicina was within the population, and only 31% was among populations. On the basis of the data comparisons of the genetic differentiation coefficient and Nei's genetic distance, the results showed that there were extremely significant genetic differentiation and appropriate genes mixture among different geographical populations. The results of cluster analysis implied that the breeding cultivars abroad were closely related to the local accessions in southern China, and the northern cultivars population was similar with P. simonii, the northeast cultivars population had close relationship with Prunus ussuriensis. The genetic structure analysis indicated that the accessions in P. salicina were divided into four types: northern cultivars population, northeast cultivars population, southern cultivars of small fruit and crisp meat population, and southern cultivars of large fruit population (including foreign breeding cultivars). 【Conclusion】 The diversity of the southern varieties were the most abundant in the P. salicina, followed by that of Northeast China varieties, foreign varieties and Northern varieties. In order to enhance the adaptability, the northeast population might be introgressed with P. ussuriensis. P. simonii might be a special type which was highly domesticated from Chinese plum in Northern China, and it had high heterozygosis owing to asexual reproduction by grafting. The large fruit accessions in Jiangsu and Zhejiang regions played an important role in modern breeding varieties abroad.

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