2022, 23(2):301-314. DOI: 10.13430/j.cnki.jpgr.20211024001
Abstract:Rice black-streaked dwarf virus disease （RBSDVD），which is caused by Rice black streaked dwarf virus（RBSDV） and mainly transmitted by small brown planthopper （Laodelphax striatellus Fallén）， is a severe viral disease in rice. Once infected, the vector small brown planthopper carries the virus for life, but it cannot be transmitted through eggs. In recent ten years, RBSDVD has been widely prevalent in rice areas of southern China，which caused serious yield reduction of rice. At present, pesticides are mainly used to control the virus vector small brown planthopper. However, due to the large population of small brown planthopper, the control effect is not good, and there are concerns about environmental pollution. Therefore, the cultivation and utilization of rice varieties resistant to RBSDVD is the optimal strategy. Within this article, we review the distribution and hazards of RBSDV, exploration of resistance germplasm resources, resistance identification methods, mapping of genes/QTLs for resistance to RBSDVD, resistance-conferring mechanism and breeding. We expect to provide insights in genetic dissection of the RBSDV resistance genes and their optimal use in rice resistance breeding.
2022, 23(2):315-322. DOI: 10.13430/j.cnki.jpgr.20211006001
Abstract:Upland cotton （Gossypium hirsutum L.），which accounts for more than 95% of the world′s cotton production，is the most important cultivated species in the Gossypium L. genus. Along with the introduction， cultivation and breeding of upland cotton in the past nearly one-hundred year in China，the genetic basis in cultivated cotton varieties gradually had become narrow. In order to broaden the genetic basis of upland cotton，the researchers and breeders have generated the genetic populations and excellent germplasm through sexual hybridization in recent decades. By taking advantage of recent achievements on molecular biology and genomics，the researchers uncovered the quantitative trait locus （QTL） in distant hybridization populations of cotton. Herein，we summarized the studies of distant hybridization in upland cotton with four tetraploid cotton species （G. barbadense L.，G. tomentosum Nutt. ex Seem.，G. mustelinum Miers ex Watt and G. darwinii G. Watt）. Generally，the genetic population which were gained from distant hybridization between upland cotton and four tetraploid cotton species，hosted excellent germplasms valuable in studies of the genetic improvement of agronomic traits，QTL mapping and gene mining. Moreover，the genetic components introgressed from G. barbadense L. to upland cotton had been found in upland cotton with a positive role during the improvement of upland cotton. Profiling from the publication of the cotton genome and its use in application of exploring cotton species，the foreseen enrichment in the genetic basis of upland cotton will become feasible in the future.
2022, 23(2):323-332. DOI: 10.13430/j.cnki.jpgr.20211011001
Abstract:Soybean （Glycine max （L.） Merr.） is an important oil crop and is often challenged by multiple stresses，thus resulting in loss of yield production and decrease of grain quality in lifecycle. WRKY transcription factors （TFs） are identified to involve into the responses to various stresses，for instance by regulating phytohormone-mediated signal transduction. The WRKY transcription factors belong to one of the TFs families found in plants. The family member generally contains one or two WRKY domain（s） which consists of approximately 60 amino acids. WRKY-TFs have been uncovered participating into the biological processes such as crop senescence， seed development，germination and dormancy，and have been also found to regulate the adaptability of plants response upon biotic and abiotic stresses. However，deciphering WRKY-TFs in soybean remains relatively insufficient. This study mainly elaborates on the research progress of the family structure/organization and their roles responding to biotic and abiotic stresses. Moreover，we propose future research focuses and hot spots to provide insights for unlocking the biological function of the WRKY family members in soybean.
2022, 23(2):333-345. DOI: 10.13430/j.cnki.jpgr.20211215001
Abstract:Field weeds are the main factors affecting crop quality and yield，and chemical weed control is the primary strategy in modern agricultural production. Acetolactate synthase （ALS），also known as acetohydroxyacid synthase，is the critical enzyme in the biosynthesis of branched amino acids in plants. ALS inhibitor herbicides are also called ALS herbicides，which inhibit the biosynthesis of branched-chain amino acids in plants by disturbing the binding of ALS to substrates，achieving the purpose of killing weeds. With the widespread application of ALS herbicides in agricultural production，the problem of herbicide residues on subsequent crops is becoming more and more serious. The impact on crop yield and quality is particularly obvious. Thus，breeding for cultivars resistant to these herbicides would bring great advantage in effective weed control. Germplasm resistant to ALS herbicides has been created in a variety of crops through chemical mutagenesis and natural mutation，and resistant varieties have been successfully developed. In this study，the characteristics，types and scope of application for ALS herbicides，the resistance mechanism of ALS herbicide-resistant crops，and the research progress of germplasm creation and utilization of ALS herbicide-resistant crops were reviewed，which provides a better understanding of crops resistant to ALS herbicides. The innovation of herbicide germplasm and variety selection can provide reference，and make a simple prediction for the possible development of ALSresistant herbicide crops in the future.
2022, 23(2):346-357. DOI: 10.13430/j.cnki.jpgr.20210930001
Abstract:Senescence，as the final stage of natural development of plants，has an important influence on crop yield. In order to promoting the selection and breeding of new crop varieties and yield improvement， it is important to deeply analyze the regulatory mechanism and influencing factors of premature senescence. Except the stress of natural environment，genetic network of crops is an important factor in regulating plant premature senescence. A variety of metabolic pathways in plants affect the period of senescence onset. Here we reviewed the various physiological，biochemical and yield changes during premature senescence in plants. Premature senescence caused degradation of chlorophyll and other macromolecules，significantly reducd leaf photosynthetic and transportion of nutrients from senescent tissues to young tissues and reproductive organs. The process was accompanied by the accumulation of reactive oxygen species （ROS），decreased the activity of antioxidant enzymes in the cells and upregulated of senescence-associated gene （SAG） expression，which eventually led to premature senescence and reduced plant yield. Premature senescence is a complex and sequential process regulated by multiple genes. We summarized the gene networks regulating premature senescence among different species，and introduced the mechanisms of premature senescence regulation through transcription factor regulation，hormone and protein metabolism. It provides suggestions on the research of premature senescence mechanism and breeding utilization in the future.
2022, 23(2):358-367. DOI: 10.13430/j.cnki.jpgr.20210602001
Abstract:Rice is one of the most important grain crops in China. The safe production of rice paddy increasingly relies on basic research in molecular biological function. The large number of PPR （Pentatricopeptide repeat） proteins is one of the relatively large protein families in rice. Studies have shown that PPR proteins are encoded by nuclear genes and is involved in the RNA processing of organelle precursor，such as RNA translation initiation，RNA stability，RNA splicing，RNA editing，regulating chloroplast and mitochondria development in rice，and then influence the growth and development of pollen，embryo，endosperm，leaf and other tissues. Inhibition of the expression of PPR proteins would seriously hinder the normal growth and development of rice. A review of rice PPR protein structure，classification，localization，RNA target sites，action mode and its influence on rice growth and development reported in recent years is provided. The functions of PPR proteins that have been reported in rice are summarized，and prospects for possible research directions like the innovation application of PPR proteins on rice germplasm resources in the future are discussed.
2022, 23(2):368-375. DOI: 10.13430/j.cnki.jpgr.20210831004
Abstract:In order to understand the natural distribution of Oryza officinalis Wall. ex G. Watt in Guangdong province and provide basis for the wild rice protection in China，the field survey of O. officinalis Wall. ex G. Watt was carried out in years of 2006，and 2012 to 2018. There were 21 distribution sites of O. officinalis Wall. ex G. Watt in 17 towns in 8 counties （cities） in Guangdong province，of which three sites were not reported in the past. Notably，47.6% of the distribution sites were less than 67 m2 or represented by only a few clusters or even one cluster，38.1% were between 67 m2 and 666 m2，and 14.3% were over 2000 m2 . The historical record indicated 79 distribution sites of O. officinalis Wall. ex G. Watt in 35 towns in 11 counties （cities） in Guangdong province. However，O. officinalis Wall. ex G. Watt was found in only 18 out of 47 distribution sites that had been surveyed in this study，suggesting the loss rate of distribution sites of 61.7%. Loss of O. officinalis Wall. ex G.Watt was found due to the construction of cities and towns，the cultivation of fruit trees and economic forests， the use of herbicides，and the rapid growth of cereal weeds，etc.. Moreover，94 accessions from 21 sites were collected and tested upon biotic stress treatments. The first results suggested 10 accessions showing resistance to brown planthopper and 11 accessions showing medium resistance to bacterial blight. These accessions were conserved ex situ at national field Genebank for wild rice （Guangzhou，Guangdong） and the national Genebank of China.
2022, 23(2):376-384. DOI: 10.13430/j.cnki.jpgr.20210812001
Abstract:To study the genetic diversity of Cerasus conradinae（Koehne）T. T. Yu & C. L. Li so as to contribute to the conservation and utilization of its germplasm，the ITS sequence was amplified by PCR and then sequenced by Sanger method，and genetic analysis software was used to analyze the genetic diversity and genetic structure of 207 individuals from 10 populations of C. conradinae（Koehne）T. T. Yu & C. L. Li in Hunan province. The nucleotide diversity and haplotype diversity of C. conradinae（Koehne）T. T. Yu & C. L. Li in Hunan province was 0.00560，and 0.792 respectively. The 207 germplasms can be divided into 14 haplotypes. Among them，the population from Zhongfang County of Huaihua City has the highest genetic diversity， followed by the population from Nanyue District of Hengyang City，and the population from Suxian District of Chenzhou City had the lowest genetic diversity. The results of AMOVA analysis showed that 60% of the genetic variation existed among the populations of C. conradinae（Koehne）T. T. Yu & C. L. Li，40% existed within the populations，and there was a large genetic differentiation among most of the populations. Among them，the genetic differentiation index between populations from Suxian District and Shimen County was as high as 0.96571. The neutral test results showed that the values of Tajima′s D（1.02121）and Fu and Li′s D（1.07527） are both positive，but statistical tests were not significant（P>0.10），the results of the mismatch distribution analysis showed that the mismatch distribution presented a bimodal curve. This indicated that the population of C. conradinae（Koehne）T. T. Yu & C. L. Li in Hunan province followed a neutral evolutionary model，and might have experienced balanced selection or sudden population shrinkage during the evolution process. Mantel test showed that there was a positive correlation between geographic distance and genetic distance among the populations（r=0.3356，P=0.026<0.05）. The genetic diversity of C. conradinae（Koehne）T. T. Yu & C. L. Li germplasms in Hunan province was relatively high，and the genetic differentiations among populations were obvious and conformed to the Isolation-by-distance（IBD）model.
2022, 23(2):385-397. DOI: 10.13430/j.cnki.jpgr.20210830001
Abstract:To understand the genetic diversity of wax gourd germplasm resources，95 wax gourd germplasm resources collected from Third National Survey and Collection of Crop Germplasm Resources in Jiangxi province were used. The cluster analysis，principal component analysis，and multivariate evaluation of 12 phenotypic traits were carried out. These results revealed abundant phenotypic variations at each of traits，with the genetic diversity index of 0.479-2.103 under different environmental conditions. The diversity index of first female flower node was the highest，followed by fruit diameter and length. The cluster analysis suggested four groups，in which group Ⅲ was large-fruit wax gourd germplasm resources with a potential forhigh-yield varieties breeding.Group Ⅳ was suitable for spending habits with heavy wax powder，little furrow and short cylinder shape，and they could be used to improve the commercial properties in Jiangxi province.The principal component analysis and comprehensive evaluation indicated that the cumulative contribution rate of the 5 main components was 67.586%. The comprehensive score of the wax gourd germplasm resources ranged from -0.92 to 1.03，the four accessions with high comprehensive scores were xinan giant wax gourd with powder，dongyuan wax gourd，xiajiang wax gourd and huangfang wax gourd，which could be used as the core breeding resources.Taken together，this result can provide an insights for variety breeding in wax gourd.
2022, 23(2):398-411. DOI: 10.13430/j.cnki.jpgr.20211027001
Abstract:158 germplasm accessions of Cymbidium goeringii （Rchb. f.） Rchb. f. from different regions were used to analyze the diversity of 20 phenotypic traits，followed by the analysis of variance，coefficient of variation analysis，Shannon-wienter index analysis，principal component analysis，cluster analysis and correlation analysis. Abundant variations on 20 phenotypic traits were observed in Cymbidium goeringii（Rchb. f.） Rchb. f. population. The coefficient of variation on the scape height and the side petal width was the largest （36.96%）. The diversity index of leaf length and leaf width was the highest （both 7.28）. The coefficient of variation on the petal type （66.32%） was the highest，followed by that of petal color （60.47%）. The diversity index of arch edge outside petal was the highest （7.28）. The principal component analysis showed that three traits including the red spot on lip，the bract tendon color，and scape color were the main factors that largely contributed to the phenotypic variation. By applying with the comprehensive score （F value），ten varieties were identified （Tian peng mu dan，Xiao fei yan，Bi yao，Du zi，Xin chun mei，Wan nian mei，Xian he，Tian xing mei，Zi jin mei and Huan qiu he ding）. These germplasm resources were divided into three groups by systematic clustering anlysis. Of them，Group-Ⅰ was medium plant type，colored flower and circle petal material，group-Ⅱ was tall plant type and pure color material，and group-Ⅲ was dwarf plant type，long leaf，colored flower and rolled petalmaterial.Altogether，this study provided insights on deciphering the phenotypic diversity of Cymbidium Sw. germplasm resources，valuable as a theoretical basis in breeding of orchid varieties.
2022, 23(2):412-421. DOI: 10.13430/j.cnki.jpgr.20210907001
Abstract:From 2016 to 2018，the project team of Guangdong province of the Third National General Survey and Collection Action of Crop Germplasm Resources conducted a systematic investigation and collection of rice germplasm resources from 59 counties（cities and districts）in the province. A total of 269 rice landraces were collected and 261 of them were identified and evaluated. The rice landraces were collected from almost throughout Guangdong province，with the exception of four prefecture-level cities around the Pearl River Delta： Shenzhen，Dongguan，Zhongshan and Zhuhai，where no rice germplasm resources were found. The agronomic traits of the collected rice resources were identified. The results indicated that the collected rice landraces were mainly indica rice，and 23 rice germplasm resources（Zhongshan 12、Baoxuan 2、Yinhuxiangzhan，etc）resistant to bacterial blight and blast were evaluated. Finally，4 rice germplasm resources with salt and drought tolerance， high amylose and aroma：Hai Dao 86，Di He Nian，Lanxi Xuan and Sanrao Xiangmi，were selected based on the overall phenotypic traits，which had high utilization value for improving rice breeding for high yield，high quality and wide adaptability in the future.
2022, 23(2):422-429. DOI: 10.13430/j.cnki.jpgr.20210831003
Abstract:Bacterial blight（BB），as a destructive disease of rice worldwide，has seriously destabilized rice yield. The most effective and environmental-friendly method in disease control is to explore and utilize the BB resistance，whereas the known resistance genes to date are limited. Wild rice populations host tremendous resistance genes，and identification of resistance genes to bacterial blight is of great significance in rice genetic improvement. In this research，the resistance to BB in common wild rice population in Guangdong province was analyzed. Although different levels of resistance to BB strains PXO99 were observed，Guangdong wild rice populations presented resistance or high resistance to the typical pathogenic strain type IV race in Guangdong. According to the genotyping result with functional markers，three sub-populations were revealed containing resistant gene Xa21，four sub-populations containing Xa4，five sub-populations containing Xa7 and Xa27. Xa23， Xa10 and Xa26 were detected in 11，12 and 16 sub-populations，respectively. The resistance genes xa5 and xa13 were not found，but 19 sub-populations contained Xa1 or its homologous gene. Resistance spectrum analysis showed that five common wild rice accessions from HY2，DB2 and GZ2 populations might contain new BB resistance genes. For BB strain race-IV，the results of variance analysis demonstrated that the BB resistance level of Gaozhou common wild rice was significantly higher than that of Huazhou，Leizhou and Taishan，while the resistance level of Huazhou and Taishan common wild rice was significantly lower than that of Lufeng. For PXO99 race，there was no significant difference in the resistance level among all wild materials. Collectively，this study provided a basis for further exploring and utilizing the excellent BB resistance gene resources of common wild rice in Guangdong province.
2022, 23(2):430-441. DOI: 10.13430/j.cnki.jpgr.20210717001
Abstract:We attempted to study the fruit quality characters in 77 Camellia oleifera Abel germplasms derived from the unique low thermal valley area of Guizhou，in order to determine the C. oleifera Abel germplasm with the best performance applicable for breeding. Fifteen characters（Single fruit weight，diameter，height，pericarp thickness，fresh seed yield，dry seed yield，kernel yield，kernel oil content，palmitic acid，palmitoleic acid， stearic acid，oleic acid，linoleic acid，linolenic acid，cis-11-eicosenoic acid）were analysed. Principal component analysis was performed to reduce the dimensionality of the data，thereby reducing the 15 main characters to four independent comprehensive indices（or principal components）.The eigen value and contribution rate of the first principal component are 5.13 and 34.19%，respectively；the eigen value of principal component 2 is 3.03，and the contribution rate is 20.17%；the eigen value of principal component 3 is 2.33，and the contribution rate is 15.51%；the eigen value of principal component 4 is 1.25，and the contribution rate is 8.35%. Principal component 1 mainly represented the kernel oil content，principal component 2 mainly represented the single fruit weight，principal component 3 mainly represented the kernel yield，principal component 4 mainly represented the fresh seed yield. Functional expression analysis was performed to obtain the comprehensive score，followed by final ranking and screening. Among the 15 traits，single fruit weight，fresh seed yield，and dry seed yield showed abundant variations. Among the different fatty acids of C. oleifera Abel oils，including palmitoleic acid and cis-11-eicosenoic acid were extremely low（≤0.35%）. Different degrees of correlation were detected between the 15 major traits. There was a significant positive correlation between kernel oil content and dry seed yield and between kernel oil content and dry kernel yield. The correlation between fatty acids was extremely significant except cis-11-eicosenoic acid. By using four principal components of characteristic value>1，a comprehensive evaluation function model based on oil tea plants in the low thermal valley area of Guizhou was established， and the top 10 C. oleifera Abel germplasms in the comprehensive score were selected（QC-8>QC-58>QC-21> QC-34>QC-32>QC-62>QC-30>QC-61>QC-59>QC-28）. Our findings indicated that single fruit weight，fresh seed yield，and dry seed yield of the 77 germplasms in the low thermal valley area of Guizhou are the traits with high breeding potential，while thickness of pericarp and other fatty acids，except linoleic acid，have high genetic stability. The dry seed yield and kernel oil content of C. oleifera Abel in the low thermal valley area of Guizhou were negatively correlated with all unsaturated fatty acids，except oleic acid. Collectively，this study provided elite germplasms QC-8，QC-58，and QC-21 as candidate parental line for breeding improved C. oleifera Abel varieties.
2022, 23(2):442-449. DOI: 10.13430/j.cnki.jpgr.20211021002
Abstract:As a traditional pulses crop in China，mungbean（Vigna radiata）plays important roles in diversifying human diets，fertilizing soils and disaster relief. However，compared with those major crops，the genetic and genomic study on mungbean has been far lagged，leading to a low efficient use of beneficial genes in breeding and a slow advance in genetic improvement of cultivars. By taking advantage of a RIL population with highdensity SNP genetic map，eleven agronomic traits（plant height，the number of branches per stem，pod length， pod width，the number of seeds per pod，seed color，seed luster，grain density，initial flowering time，content of chlorophyll and 100-seed weight）were investigated and mapped in this study. The results showed that the seed color was controlled by a single nucleus-encoded gene，whereas the segregation of seed luster became much complicated. For quantitative traits，a normal distribution on the frequency of 100-seed weight was observed. For 11 traits，20 QTLs were revealed from 14 genomic regions on 8 linkage groups. QTLs at LG3，LG5 and LG10 were both detected with multiple traits，and the target regions were overlapped. Four QTLs were detected with pod length，explaining 5.5%-12.3% of phenotypic variations. For the traits number of seeds per pod，seed luster，seed color and number of branches per stem，one QTL per trait was detected. The major QTLs for seed color and seed luster contributed 69.7% and 61.0% on phenotypic variation，respectively. Gained from annotation using KEGG and SNP variations，18 genes were proposed to be candidates associating with these 11 traits. Collectively，these results provided a basis for future characterizing these candidate genes and marker-assisted selection in mungbean breeding.
2022, 23(2):450-459. DOI: 10.13430/j.cnki.jpgr.20210721003
Abstract:Soybean cyst nematode（SCN）race 2 is predominant in the Huang-huai Rivers valley. Out of 333 soybean accessions that have been tested for the resistance to SCN race 2（SCN 2）since 2017，19 resistant accessions including 5 resistant and 14 moderately resistant have been identified. Genotyping using KASP markers showed that all the 19 resistant accessions harbored two resistant loci rhg1 and Rhg4. The genotypes of KASP markers linked to rhg1 and Rhg4 for 18 accessions were the same as PI90763，while Yuanheidou was consistent with PI437654. Moreover，resistant genotype Zheng 12915 and Zheng 12929，which were developed from resistant germplasm Huipizhiheidou showed agronomic performance better than the parental line. Collectively， these results provided a basis for SCN breeding in soybean.
2022, 23(2):460-467. DOI: 10.13430/j.cnki.jpgr.20210903003
Abstract:This study analyzed the combining ability and heritability of the antioxidant active ingredients of red rice，which will provide theoretical reference for breeding of hybrid red rice rich in functional nutrients. By deployment of 6 three-line sterile lines and 8 red rice restorer lines to generate 48 hybrids of red rice following the incomplete diallel hybridization 6×8（NCII），the combining ability and genetic parameters of total phenols，total flavonoids，procyanidins and anthocyanins were analyzed. The results showed that there were genetic differences in the content of total phenols，total flavonoids，procyanidins and anthocyanins among the red rice hybrid combinations，which were affected by the additive effects of the sterile line parents and the non-additive effects between the combinations. The contents of total phenols，total flavonoids and proanthocyanidins were mainly controlled by the non-additive effects of genes，and the content of anthocyanins was affected by the interaction of additive and non-additive effects of genes. There was no direct correlation between the parental general combining ability（GCA）and the combined special combining ability（SCA），and there was no obvious correlation between the female parent with different brown rice color and the special combining ability of the red rice combination. The heritability analysis showed that the narrow-sense heritability of the four antioxidant active ingredients ranged from 12.99%-48.29%，which should be effective for selection in the middle and high generations. The contribution rate of the four antioxidant active ingredients of the sterile lines was greater than that of the restorer lines. The selection of female parents should be strengthened in the breeding of red rice hybrid rice. The female parents Yexiang A and Pinhong 1A were better in the breeding of red rice antioxidant active ingredients. Hybrid combinations Yexiang A×18Rr175 and Guang 8A×18Rr178 had high special combining ability effect value and great potential for production and application.
2022, 23(2):468-479. DOI: 10.13430/j.cnki.jpgr.20210915001
Abstract:Eleven agronomic traits and 2 quality traits in 303 soybean germplasm resources collected from Huang-Huai-Hai region were studied by using variation coefficient and Shannon-Weaver Information index. Principal component analysis，correlation and regression analysis were used to evaluate the soybean germplasm resources and select important characteristics，which provides reference for soybean germplasm resources innovation and breeding in Huang-Huai-Hai Region. The results showed that variation coefficients of 13 descriptive traits ranged from 5.52% to 27.61%，and growth duration，seed number per pod，protein content，and fat content remained relatively stable，while large variations were found in plant height，seed number per plant， pod number per plant，seed weight per plant，and 100-seed weight. Meanwhile，Shannon-Weaver Information index of the above traits ranged from 1.9906 to 2.0956. Cluster analysis divided the 303 soybean germplasm resources into 7 Groups. Group V，which had excellent overall traits，was suitable for use as breeding materials in Huang-Huai-Hai Region. The cumulative contribution of the top 4 principal factors reached 75.051% in principal factors analysis. The first principal factor was related to pod number per plant and seed number per plant，the second principal factor was related to protein content and fat content，the third principal factor was related to seed size，the fourth principal factor was related to single plant yield. The average F value from the evaluation of phenotypic traits of 303 soybean germplasm resources was 0.549. Lianshui Tianedan（ZDD04189）had the highest F value（0.935），and Jinpin 42（ZDD23089）the lowest F value（0.207）. Five phenotypic traits：growth duration，plant height，seed number per plant，seed weight per plant，and protein content，were selected as an evaluation index of phenotypic traits of soybean germplasm resources in Huang-Huai-Hai region by stepwise regression analysis.
2022, 23(2):480-492. DOI: 10.13430/j.cnki.jpgr.20210918001
Abstract:To unlock the physiological responses of P. betulaefolia Bunge germplasm resources and identify the elite resources under saline-alkali stress conditions，>3000 seedling plants from 17 betulaefolia Bunge accessions in Gansu，Shanxi and Liaoning provinces were analyzed. The physiological indexes under the mixed stress treatments of neutral salt and alkaline salt were measured，followed by statistical analysis（principal component analysis，heat map，cluster analysis and stress coefficient）. In P. betulaefolia Bunge plants showing strong tolerance，the antioxidant enzyme activity and proline content increased significantly after treatments. Under 300 mmol/L salt-alkali stress，the SOD activity in P. betulaefolia-Hedi 3 and P. betulaefolia-Pinglu 1 was observed with increase up to 75.04% and 70.04%，respectively. The increase on the POD activity in P.betulaefolia-Gansu 1 and P. betulaefolia-Hedi 1 was detected up to 1136.11% and 742.86%，respectively. In P. betulaefolia-Gansu 15 and P. betulaefolia-Gansu 4 a significant increase（344.58% and 343.42%，respectively） on the CAT activity was detected. Moreover，the significant increase on proline content were observed in P. betulaefolia-Pinglu 2，P. betulaefolia-Hedi 1 and P. betulaefolia-Hedi 3 and MDA content were observed in P. betulaefolia-Gansu 16，P. betulaefolia-Gansu 13 and P. betulaefoli-Gansu 1. Except for P. betulaefolia-Gansu 13 that showed salt damage at low concentration（100 mmol/L）under saline-alkali stress，other P. betulaefolia Bunge resources showed degrees of salt damage under 300 mmol/L. By deployment of the principal component analysis，P. betulaefolia-Hedi 1，P.betulaefolia-Hedi 3，P. betulaefolia-Pinglu 1，P. betulaefolia-Gansu 15 and P. betulaefolia-Shanxi 1 showed strong salt-alkali resistance. Based on heat map and cluster analysis，it was found that P. betulaefolia-Gansu 4，P. betulaefolia-Gansu 15，P. betulaefolia-Pinglu 1，P. betulaefolia-Hedi 1 and P. betulaefolia-Hedi 3 had strong salinity tolerance. The coefficient analysis suggested that P. betulaefolia-Gansu 1，P. betulaefolia-Hedi 1，P. betulaefolia-Gansu 16，P. betulaefolia-Gansu 4，P. betulaefolia-Gansu 15 showed strong salt and alkali tolerance. Taken together，P. betulaefolia Bunge. P. betulaefolia-Hedi 1 and P. betulaefoliaGansu 15 are qualified with high saline-alkali resistance，whereas P. betulaefolia-Gansu 13 is saline-alkali sensitive.
2022, 23(2):493-504. DOI: 10.13430/j.cnki.jpgr.20211225001
Abstract:To analyze the yield potential of common wheat（Triticum aestivum L.）using high-grain weight germplasm resources in Ningxia，here we conducted the field trials for detecting grain weight under the ecological conditions of the Yellow River irrigation area，as well as marker-assisted analysis using four functional KASP markers TaGW2-6B，TaGASR，TaGS-D1 and TaCWI-4A. Four grain-related traits consisting of the thousand-kernel weight（TKW），kernel length（KL），kernel width（KW）and kernel thickness （KT）of 209 wheat germplasm resources were measured for 2 consecutive years. The results showed that wheat germplasm resources had abundant diversity on grain-related traits. The distribution ranges of TKW，KL，KW and KT values were 29.73-56.25 g，5.82-7.57 mm，2.87-3.83 mm and 2.74-3.55 mm，respectively. For TaGW2-6B，two haplotypes （Hap-6B-1 and Others）were detected，while the elite haplotype Hap-6B-1 accounted for 62.44%. For TaGASR two haplotypes（H1c and H1c/H1g）were detected，while haplotype H1c accounted for 93.10%. Two haplotypes Hap-4A-C and Hap-4A-T at TaCWI-4A-1523 were revealed，and the elite haplotype Hap-4A-C accounted for 76.41%. Two haplotypes TaGS-D1a and TaGS-D1b at the TaGS-D1 were revealed，and the elite haplotype TaGS-D1a accounted for 86.50%. The locus TaGW2-6B was found to be significantly correlated with TKW and extremely significantly correlated with KW and KT. TaGASR was found to be significantly correlated with TKW， KL and KW. TaCWI-4Awas found to be significantly correlated with TKW，KW and KT. Based on the genotyping results，seven haplotype combinations were revealed. The combination of Hap-6B-1+H1c+Hap-4A-C+TaGSD1a represented a significant positive effect on TKW，KW and KT，while the combination of Hap-4A-C+TaGSD1a represented a significant positive effect on KL. Taken together，three genes TaGW2-6B，TaGASR and TaCWI- 4Amight become elite makers on selection of the wheat grain weight under the ecological conditions of the Yellow River irrigation area in Ningxia. Out of 209 tested genotypes，14 high-grain weight genotypes（1000-kernel weight > 50 g）were identified，and nine of them have stacked elite haplotypes of four grain weight-related genes.
2022, 23(2):505-517. DOI: 10.13430/j.cnki.jpgr.20210819003
Abstract:The petals of blooming peach flowers can be large and showy，or small with curved edges（nonshowy），while showy and double flower is desirable in terms of breeding ornamental peaches. Since few studies are conducted to detect the molecular markers linking with the non-showy/showy flower trait，that restricts the molecular breeding for this trait in peach. In the present study，by taking use of re-sequencing data generated from 199 peach varieties and 1042687 single-nucleotide polymorphisms（SNPs），we performed the genome-wide association scanning（GWAS）for the non-showy/showy flower trait. Using a general linear model（GLM），we thereby identified seven signals that were associated with the flower trait on Chr. 2 and Chr. 8. Three SNPs on Chr. 8 were validated using kompetitive allele-specific PCR（KASP）genotyping in five F1 populations. The SNP on Chr. 8 at 14484624 bp was highly associated with the targeted trait based on the χ2 test. Based on the correlation of the genotyping and phenotypic results of five F1 populations，the highest accuracy was 93.46% at Chr. 8： 14484624 bp. RNA-seq analysis of different tissues and gene annotation enabled identifying one gene（Prupe.8G118100）that showed tissue-specific expression in flower. Collectively，this work identified one SNP which is highly associated with the non-showy/showy flower trait，and one candidate gene，which could facilitate markerassisted selection for ornamental peaches.
2022, 23(2):518-526. DOI: 10.13430/j.cnki.jpgr.20210827002
Abstract:The hybrid breeding in soybean（Glycine max）mainly relies on the three-lines system derived from cytoplasmic male sterility. Identification of optimal restorer lines is therefore of importance. Since checking the fertility of F1 hybrids derived from the tested restorer lines crossing with sterile lines is time-consumption and laborious，genetic identification of the strong restorer-of-fertility（Rf）gene（s）and its use for markerassisted selection（MAS）will greatly improve the efficiency of breeding. In this study，the F2 segregation population derived from the CMS-RN type sterile line JLCMS204A（female parent）and the restorer line JLR230（male parent，containing the unknown Rf gene）was investigated. Through examining pollen fertility the Rf gene in the restorer line was controlled by a pair of dominant single gene. Based on the bulked segregant analysis（BSA）of both parents and two pools（fertile and semi-sterile），the genetic locus named GmRf1 was allocated on chromosome 16 flanked by simple sequence repeat（SSR）markers BARCSOYSSR_16_1069 and BARCSOYSSR_16_1076. By taking use of enzyme digestion amplified polymorphic sequences（dCAPS） makers，insertion deletion（InDel）makers and sequence tag site（STS）makers，GmRf1 was finally delimited between the marker dCAPS-1 and BARCSOYSSR_16_1076，in which the genetic distance were 0.1 cM and 0.3 cM， respectively. On the basis of the ZH13 v2.0 reference genome，GmRf1 was located between 32 708 896 bp and 32 932 950 bp with a physical distance of 224.1 kb. This study will lay the foundation for molecular marker assisted breeding of the restorer lines containing GmRf1 locus and the isolation of the GmRf1 gene.
2022, 23(2):527-540. DOI: 10.13430/j.cnki.jpgr.20210912001
Abstract:Lignin is the key component in the secondary cell wall of plants，which provides mechanical support and promotes water transport as well as has important impact responding to various biological and abiotic stresses. Averrhoa carambola L. is an important economic and ornamental species，the growing zone of which is restricted by its sensitivity to environmental stress conditions，such as strong wind，cold，and drought. However，lignin has significant impact on the improvement of stress resistance.To explore the lignin biosynthesis process of A. carambola L.，the issue microstructure was visualized using paraffin sections，and the changes of lignin content and enzyme activity were measured at different development stages of twigs. Bioinformatic analyses based on genome sequencing and transcriptome profiling were conducted to identify structural genes and transcription factors that associated to the lignin biosynthesis. The results showed that the increase on the activity of three enzymes（PAL，CAD and POD）and on the lignin content，as well as the appearance of xylem cells were observed along with the twigs development. A total of 41 structural genes，transcription factors（12 AcaMYBs and 11 AcaNACs）were identified in the A. carambola L. genome，followed by analyzing the differential expression patterns of these genes. The results of qRT-PCR found that AcaPAL1，AcaC3H2，AcaC4H2，AcaF5H1 and AcaMYB18 exhibit obvious tissue specific expression pattern，indicating these are specific genes related to lignin biosynthesis. Co-expression network analysis showed that AcaNAC29，AcaNAC39 and AcaMYB47were the essential regulatory genes of lignin biosynthesis. Collectively，this study provided important information to facilitate future research on the transcription factors and structural genes of lignin biosynthesis in A. carambola L..
2022, 23(2):541-552. DOI: 10.13430/j.cnki.jpgr.20211106001
Abstract:Spring-sowing soybean in Jiangxi province of China is mainly planted in the red hilly soil region， where low phosphorous availability restricts the yield production. Breeding for spring soybean cultivars showing high phosphorous use efficiency will hence become of interest to ensure its production in Jiangxi province. To understand the phosphorous efficiency of spring soybean cultivars and their foundation parents，12 traits （i.e. net photosynthetic rate，biomass，phosphorous absorption efficiency，phosphorous use efficiency，and phosphorous concentration） were evaluated under normal and low phosphorous soil pot conditions，followed by the analysis of the principal component and associated membership functions. There were significant differences in 12 traits including net photosynthetic rate，phosphorus absorption efficiency and phosphorus use efficiency among 17 soybean cultivars. Gained from the comprehensive analysis，the cultivar Brazil 11 was qualified as a high-efficiency phosphorous germplasm，whereas Heinong 35 was a low-efficiency phosphorous germplasm. Moreover，the phosphorous efficiency of cultivars Gandou 10，Gandou 11 and Gandou 12 derived from the parental cultivar Brazil 11 was higher than that of other soybean cultivars in Jiangxi，showing higher tolerance under low phosphorous stress condition. These spring soybean cultivars significantly enhanced the tolerance to low phosphorus stress，and thus became important to promote the development of spring soybean in Jiangxi province.
2022, 23(2):553-562. DOI: 10.13430/j.cnki.jpgr.20210914003
Abstract:Waterlogging seriously affects the yield and quality of cotton，whereas the waterlogging tolerance as a complex agronomic trait is difficult for quantification on a large scale using traditional methods. Seeking an efficient method for identifying cotton genotypes showing waterlogging tolerance might guarantee cotton breeding for quality and yield. Hyperspectral technology is a nondestructive and efficient method for crop detection can quickly identify cotton seedlings showing waterlogging resistance. In this study，the plant height，stem diameter，leaf area，and total root length of 27 cotton varieties were measured under hypoxia stress or normal oxygen conditions. Portable spectrometer was used to obtain its spectral image，analyze the waterlogging characteristic curve and extract six spectral indexes related to pigment，moisture and nitrogen. Multivariate analysis methods such as principal component analysis，stepwise regression，systematic clustering，and correlation analysis were adopted to construct a cotton seedling waterlogging tolerance identification model based on hyperspectral images. Principal component analysis showed that 10 individual indicators of waterlogging tolerance might be simplified into four principal components，which were further simplified into the D value of the comprehensive evaluation coefficient of waterlogging tolerance by considering the contribution rate and weight of the principal component and the normalized feature vector. Stepwise regression analysis was performed to establish the optimal linear regression equation of D value and 10 single index waterlogging tolerance coefficients：D=0.161+0.220 SD+0.068 LA+0.358 PSSRa +0.404 I1+0.292 NDSI （R2=0.9849，SD：stem diameter，LA：leaf area，PSSRa：pigment specific simple ratio a，I1：infrareed index 1，NDSI：normalized diffiferent stress index）. Cluster analysis of 27 cotton genotypes suggested four grades of waterlogging tolerance，including extreme waterlogging tolerance，waterlogging tolerance，medium waterlogging tolerance，and waterlogging sensitivity. The correlation analysis showed that stem diameter was significantly positively correlated with pigment ratio index a， pigment ratio index b， plant nitrogen spectral index， normalized difference stress index， and infrared index 1，but had no significant correlation with normalized difference water index. The total root length was significantly negatively correlated with pigment ratio index a， plant nitrogen spectral index， and normalized difference stress index，but had no significant difference with normalized difference water index and infrared index 1. There were no significant correlations between leaf area and plant height and the other 9 individual indicators. Collectively，this study highlighted the hyperspectral imaging technology as a useful method to identify the waterlogging tolerance of cotton.
2022, 23(2):563-574. DOI: 10.13430/j.cnki.jpgr.20210923002
Abstract:Glutelin is the main component of rice storage proteins，and its content and composition directly affect the rice grain quality and nutrition. In rice endosperm，glutelin is synthesized in the form of 57 kDa precursor in endoplasmic reticulum，followed by the cleavage and deposition in the storage vacuoles through complex cytological transport pathways. Although 10 key genes required for glutelin synthesis，transport and deposition have been identified，their molecular regulatory network remains dissected in details. In this study，we identified a glutelin precursor accumulation mutant named T360 from the Nipponbare tissue-cultured mutagenesis population. Genetic analysis showed that the mutant phenotype of T360 was controlled by a single recessive nuclear-encoded gene. Through map-based cloning the candidate gene in this mutant was delimited to a 248.9 kb physical interval on chromosome 4. Gene annotation analysis showed that OsVPE1 coding β-vacuolar processing enzyme found in the genetic region is a candidate responsible for the maturation of glutelins. No mutation in OsVPE1 at the genome sequence was identified，whereas its expression was significantly down-regulated. Expressing the wild-type OsVPE1 genomic sequence in the mutant is able to complement the mutant phenotype， despite of no difference on DNA methylation revealed in wild type and T360. Altogether，this work provided an important mutant to decipher the molecular regulation mechanism of the VPE1 gene in rice.
2022, 23(2):575-582. DOI: 10.13430/j.cnki.jpgr.20210823001
Abstract:Raffinose family oligosaccharides（RFOs）are one of important osmoregulatory substance in plants. Galactinol synthase（GolS）is a key enzyme in the synthesis of RFOs. In this study，GmGolS1 was cloned from soybean based on sequence homology. GmGolS1 was found on chromosome 3 with three introns. The full length open reading frame（ORF）of GmGolS1 was 1020 bp，which encodes 339 amino acids with the molecular weight of 38.82 kDa，and the isoelectric point of 5.47. The amino acid sequence GmGolS1 has characteristics that are commonly detected in plant GolS proteins：a conserved serine phosphorylation site，a manganese ion binding associated DXD element，and a carboxy-terminal hydrophobic pentapeptide. The phylogenetic analysis showed that GmGolS1 was closely related to AmGolS and MtGolS. Real-time fluorescence quantitative PCR analysis showed that GmGolS1 was inducible upon heat，low temperature，drought and salt stresses in different degrees in seedlings，and the most abundant expression was observed under heat stress treatment. By transforming GmGolS1 was into tobacco，four transgenic lines were identified using genomic DNA PCR and real-time fluorescence quantitative PCR. Test for GolS enzyme activity showed that the transcribed product of GmGolS1 in transgenic tobacco played the catalytic activity of GolS. Gained from plant phenotype，electrolyte leakage，soluble carbohydrate content and malondialdehyde content of GmGolS1 transgenic tobacco under heat stress，GmGolS1 was found correlating with improved heat resistance in transgenic tobacco.
2022, 23(2):583-591. DOI: 10.13430/j.cnki.jpgr.20210926001
Abstract:Wx gene directly controls the synthesis of amylose in rice endosperm，and thus affects many cooking quality traits such as gel consistency，which is the major gene controlling the eating quality of rice. It can significantly improve the rice eating quality by moderately reducing amylose content（AC）. Jifeng B（JB） is a maintainer line of indica hybrid rice with high AC，which reduces the eating quality of the progeny. CRISPR/ Cas9 technology has been applied more and more in rice molecular breeding. In this study，four target sites were selected from the upstream sequence of coding region of Wx gene，and the editing vector was constructed and introduced into JB by Agrobacterium tumefaciens. A total of 9 transgenic lines，L1-L9，were obtained. Among them，L8 and L9 had a large fragment deletion mutation，in which the expression of Wx gene and AC were downregulated. The gel consistency and eating quality were also improved. There is a great difference in the appearance of brown rice between L8 and L9. L8 is similar to glutinous rice and L9 is similar to sticky rice. To sum up，we used CRISPR/Cas9 technology to edit the upstream untranslated region of Wx gene in order to reduce the AC in rice，and achieved success. These results provide a reference for the study of rice quality improvement.
2022, 23(2):592-604. DOI: 10.13430/j.cnki.jpgr.20210927001
Abstract:Wheat（Triticum aestivum L.）is an important food crop worldwide. However，its growth has been heavily suppressed by salt stress. The molecular mechanisms of salt tolerance in wheat remain unclear. In this study we conducted research to decipher the mechanism of salt stress response in Jimai19 using NaCl treatment and time-course RNA sequencing. The total number of differentially expressed genes（DEGs）in response to salt stress was 5526 in wheat roots. Based on Gene Ontology（GO）and Kyoto Encyclopedia of Genes and Genomes （KEGG）analysis，it was found that DEGs were significantly enriched in the categories of plant hormone signal transduction，primary metabolic processes such as amino acid synthesis，and some secondary metabolic processes in the early stages of salt treatment. After 6 h of salt treatment，the DEGs involved in stress response began to enrich. With the extension of stress time and the damage to plant increased，the DEGs related to macromolecular complex，DNA conformational changes，protein-DNA structural changes etc，were enriched at 48 h and 72 h of salt treatment. Many genes involved in signal transduction，resistance to oxidative stress，osmotic stress，ion balance and amino acid sythesis were differentially expressed at different stages of salt treatment. Most genes of the last three classes were induced by salt stress. These results provided valuable information on the salt tolerance of molecular mechanisms in wheat.
2022, 23(2):605-613. DOI: 10.13430/j.cnki.jpgr.20211013001
Abstract:To improve blast resistance of the rice cytoplasmic male sterile（CMS）line SanxiangA and its maintainer SanxiangB，a PCR-based co-dominant InDel marker CoInDF1R1 was developed to select the broadspectrum and durable blast resistance gene Pi9 in breeding practice. By performing the greenhouse inoculation assay using twenty-eight Magnaporthe oryzae strains isolated from different rice areas in China and abroad， the Pi9 gene donor rice line 75-1-127 showed much higher resistance frequency（85.71%）than that of two acceptor parents SanxiangA and SanxiangB（28.57%）. The Pi9 functional marker CoInDF1R1 produced a 320 bp fragment in 75-1-127 and a ca. 410 bp fragment in both SanxiangA and SamxiangB. A CMS line SanxiangAPi9 and the corresponding maintainer SanxiangB-Pi9 both showing significant blast resistance were obtained by taking advantage of a ten-year consecutive backcross breeding practice and CoInDF1R1-assisted selection. In the natural disease nursery，SanxiangA-Pi9 and SanxiangB-Pi9 as well as the Pi9 donor line showed highlevel blast resistance at the seedling stage，whereas two acceptor parents SanxiangA and SanxiangB remained highly susceptible. Pollen I2-KI staining and field bagged seed-setting assays showed that SanxiangA-Pi9 and SanxiangA with sparse circular abortive pollens under microscope and no self-pollinated seed was obtained. On the contrast，SanxiangB-Pi9 and SanxiangB expressed normal pollen staining reaction and fertility. Furthermore， SanxiangA-Pi9 represented excellent cross-pollination traits，its stigma exsertion rate reached 61.70%. In the field cultivation assay，SanxiangA-Pi9 and SanxiangB-Pi9 showed complete uniformity as their acceptor parents on main agronomic traits，while possessed much more spikelets per plant，thus implying promising yield and heterosis.
2022, 23(2):614-623. DOI: 10.13430/j.cnki.jpgr.20211031001
Abstract:Drought is the primary abiotic factor that affects the yield and quality of cotton fiber. ROP （Rho-realted GTPases from plants）protein is a type of plant-specific Rho small G proteins，and in plants this protein plays a role in responses to the development and various stresses. In this study，real-time quantitative polymerase chain reaction（qRT-PCR）was used to analyze the expression pattern of the GhROP4 gene under drought stress and exogenous abscisic acid（ABA）treatment conditions. Virus-induced gene silencing（VIGS） technology was used to analyze the regulation mode of the GhROP4 gene on drought and the possible regulatory pathways involved. Drought and abscisic acid treatment increased the transcription level of GhROP4 gene as a whole，and silencing GhROP4 gene enhanced the drought resistance of cotton. The water loss rate and relative water content，proline（Pro，Proline）content，and activities of three antioxidant enzymes：catalase（CAT）， superoxide dismutase（SOD），and peroxidase（POD）of the detached leaves of the silent plants after drought stress were significantly higher than those of the negative control. The contents of hydrogen peroxide（H2O2）and malondialdehyde（MDA）were significantly lower than those of the negative control；compared with the negative control，ABA synthesis and pathway gene expression in the leaves of silent plants were significantly up-regulated. Altogether，our results supported that the GhROP4 gene was a negative regulator in drought resistance of cotton through negatively regulating the ABA metabolic pathway