Abstract:Crop germplasm are basic resources for global food security and sustainable development and material base for original innovation of agricultural science and technology and development of modern seed industry. The science of crop germplasm resources is a scientific discipline devoting to the research on diversity and its use of crops and their wild relatives. The three basic theories of the science include the theory of centers of origin of cultivated plants， the law of homologous series in variation and the synergistic evolution theory of crop germplasm resources and cultural environments and social development. The basic attributes of the science include genetic diversity， genetic specificity， genetic integrity and genetic accumulativeness. The science covers theories， technologies， management and systems involving in survey， conservation， evaluation， research， germplasm enhancement and sharing service of crop germplasm resources. This paper establishes the theoretical framework of the science of crop germplasm resources， defines basic concepts and attributes related， and proposes development strategies of the science， esp. in China.

Abstract:Since 1990s， scientists have mapped many quantitative trait loci through bi-parental populations such as NILs， DH， and IBD in plants through co-segregation between traits and markers. A set of important genes have been isolated by fine mapping， which are relating to biotic and abiotic stress resistance， environment adaptation， quality， and yield. These bring a lot of new biological knowledge. However， most of these genes were selected successfully in domestication and breeding.By 2010， with the establishment of reference genome sequences for most crops， genome re-sequencing has broken the limitation of the number of molecular markers， driving crop genetic research fully entering the genome era. Millions of SNP markers have made genome-wide association study （GWAS） widely used in genetic resources research， making it the most important part of germplasm resources research in the past 10 years. In this golden period， dissecting genetic basis of important agronomic traits through GWAS has become the main content of Cell， Nature and Science and their sub-publishers.In the last century， the establishment and development of crop breeding science promoted establishment of germplasm resource discipline. The development and wide application of genomics in this century has gradually formed a new situation in which research of germplasm resources promotes the development of breeding. Many problems that plague breeders have received important enlightenment or answers through GWAS analysis （such as tomato domestication， breeding history， contradiction between quality and yield， founder genotype， etc.）. Further， the pan-genome research breaks through the limitations of a single reference genome， makes researchers realize the universality of genomic structural variations within a species， and provides a broader perspective for analyzing the formation of landmark cultivars， founder genotypes and the creation new super-cultivars. NAM， MAGIC， and the ideas and practice of constructing new multi-parents genetic mapping populations based on these can make the background level of the mapping population basically reaching the level of the breeding population at the same time， speeding up the fine mapping of agronomically important genes and pre-breeding. This has driven integration and interaction of germplasmics， genomics and breeding. Furthermore， in assistance of speed breeding and gene editing technology， the integration and interaction will surely promote the three disciplines to enter a new time.

Abstract:Crop germplasm resources are the heritages of human through long-term breeding and passing on process， and strategic resources of ensuring food security and sustainable agricultural development. The property rights regime plays a key role in ensuring the national germplasm resources safety， encouraging the germplasm enhancement activities， and promoting the conservation and sustainable utilization of crop germplasm resources. In China， the property rights regime is complex， and protection system is incomplete. This paper， on the basis of elaborating the theory framework of crop germplasm resources， elaborates the concepts and contents of human rights to survival， sovereign rights and farmer's rights， which form the basic rights over crop germplasm resources； explores the options and possibilities on recognizing and granting the ownerships of state， community and individual for property rights over crop germplasm resources； expounds the functions of protecting crop germplasm resources by intellectual property rights， including plant new variety rights， trademark rights， geographic indicators， important heritage of agricultural culture and patent rights. Finally， authors look into the trends and propose the priorities in developing property rights system of crop germplasm resources in view of the actual needs in ensuring food security and sustainable agricultural development. It is a reference for researchers and policy makers on the areas of crop germplasm resources.

Abstract:The crops， including apple， pear， citrus， banana and other fruit tree crops， and potato， sweet potato， cassava and other tuber crops， as well as rubber， coconut， oil palm and other tropical economic crops， have to be planted through propagules such as plants， roots， tubers， bulbs and seed stems. Based on the difference on long-term conservation strategy， these species are referred “field genebank conservation crops”. In the past 40 years， through the construction of conservation facilities， technical procedures on sampling and preservation， as well as backup preservation， the strategy of safe conservation of germplasm resources in germplasm field has been created in National Field Genebanks of China. With the application of newly-established in vitro and cryopreservation facilities in National Crop Genebank of China， a preliminary integrated conservation system， including the National Field Genebanks as the core， in vitro genebank， cryopreservation genebank and in situ protection sites， is able to guarantee the long-term safe conservation and continuous utilization of diversified field genebank preservation crops. By December of 2021， forty-three National Field Genebanks have maintained 69，504 accessions of 1，469 species or subspecies， hosting the largest number of accessions in the world. This article reviews the reproductive characteristics of the conserved germplasm resources in National Field Genebanks of China， the factors that affect safe conservation and the corresponding strategies that address to these factors， as well as the practical applications and prospects of the conservation facilities system， in order to provide insights on safe preservation of these special germplasm resources in China.

Abstract:Maize （Zea mays L.） is the most important food and feed crop which plays an important strategic role in food security in China. Maize is the monoecious plant species， tassel is panicle and ear is spadix. The differentiation and development of inflorescences and florets are the basis for the number and fertility of florets in maize ultimately resulting in a formation of grain yield. Therefore， this research field is of significant interest and fruitful achievements have been made. In the past few years， in order to improve maize grain yield and further analysis the molecular network of yield formation， the latest progresses in the field of genetic modulation and regulatory mechanism on inflorescence branching and kernel number have been reported. In this paper， we briefly summarize our understanding of the genes and their acting pathways in the development of inflorescence branches， spikelets and florets. This review focuses on the inflorescence-specific transcription factors， non-coding sequences and their regulators， enzymes involved in the reactive oxygen species （ROS） scavenging and carbohydrate metabolism， key factors in ethylene biosynthesis and signal pathway， and major players in membrane system and signal transduction. And we make prospects for the development of biotechnology to promote whole genome sequence analysis， interaction network analysis of hormones and metabolites， and precision breeding. We aim to provide an insight in understanding of the crucial genetic factors and pathways controlling inflorescence development， which has implications for future research on the genetic regulatory network of inflorescences and florets， as well as on the high-yield breeding in maize.

Abstract:Nucleolar dominance plays an important role in plant polyploidy. Polyploid can cope with the genetic changes in polyploidy via regulating the expression of rDNA genes to control the number of ribosomes. The rDNA gene expression regulation， which is controlled by the chromatin state rather than by the DNA sequence， is a large-scale and global pattern， and genes silencing usually occurs in the whole nucleolus region. Nucleolar dominance contributes to the protein synthesis and the genome stabilization. Chromosome elimination may be a way to response mechanism in polyploidy. Although the link between nucleolar dominance and chromosome elimination is supported by tremendous evidences， the genetic mechanism remains unclear， especially the genome specificity of chromosome elimination. Therefore， further research on the genetic mechanism will reveal the role of nucleolar dominance in the formation of polyploidy. The purpose of this study is to explain how plants cope with the genomic shock of polyploidy through nucleolar dominance， and to provide an insight in polyploidization.

Abstract:Rice is one of the most important crops worldwide. In recent years， with the improvement of life quality， people have paid more attention to the taste of rice. Endosperm is the main component of rice grain， which provides energy for seed germination and embryo development. Starch accounts for about 80% in rice grain. Unlocking the molecular mechanism of starch synthesis becomes of theoretical significance and application value in improving rice quality. Although the general pathway of starch synthesis has been relatively illustrated， this process is still complicated considering the genetic and environmental interaction under field conditions. Due to the difficulty of phenotypic identification， it is hard to genetically map and isolate the genes/QTL affecting rice quality. Mutants defected in starch synthesis obtained by physical and chemical mutagenesis were mostly controlled by single nuclear gene mutation and usually showed floury endosperm due to changes of starch grains morphology or loosely packed starch filling in rice. The mutated genes could be cloned by population construction using homozygote obtained through generational breeding. In recent years， scientists have basically cloned many genes participating in multiple biological processes using these mutants， perfected the regulation pathway of starch synthesis. This paper summarizes these starch synthesis related mutants isolated in recent years， and discusses different metabolic pathways involving in starch synthesis， which expects to provide reference for rice breeding and quality improvement.

Abstract:In recent years， cadmium and arsenic contamination in China's farmland has became increasingly serious， resulting in the occurrence of excessive cadmium and arsenic in grains. Rice is the main food for about half of the world's population. Cadmium and arsenic in the soil will accumulate in the human body through the enrichment of the food chain after being absorbed by rice， thereby harming human health. Therefore， reducing the accumulation of cadmium and arsenic in rice has became an urgent and important issue to ensure grain quality security and promote the development of rice industry. To study the accumulation mechanism of cadmium and arsenic in rice and to cultivate rice varieties with low accumulation of cadmium and arsenic is the most economical way to solve the excessive cadmium and arsenic in grains， which is of great significance to realize the safe production of rice in contaminated farmland. In this review， we summarize the morphology and bioavailability of cadmium and arsenic in farmland， the molecular mechanism of cadmium and arsenic uptake and transport in rice， and the main mechanism of rice tolerance to cadmium and arsenic. We also review the progress in breeding of rice cultivars with low cadmium and arsenic level in grains， and prospected the future development direction. The purpose of this paper is providing some references for reducing cadmium and arsenic content in rice grains.

Abstract:Thinopyrum á. L?ve， is one of the more widely used wild resources in the genus Triticum L.， and an important donor source in wheat genetic improvement and germplasm innovation. The creation of Trititrigia Tzvelev began in the 1920s， which refered to the introgression of chromosome or genome genetic components of Thinopyrum á. L?ve into common wheat through distant hybridization， including Trititrigia Tzvelev （partial） amphidiploid， alien addition line， alien substitution line， translocation line and introgression line. The Trititrigia Tzvelev amphidiploid （partial） were mainly octaploid Trititrigia Tzvelev （AABBDDXX， 2n=8x=56） and hexaploid Trititrigia Tzvelev （AABBXX，2n=6x=42）. Most of the chromosomes （XX） from Thinopyrum á. L?ve were mixed chromosomes （heterologous chromosomes）. Since the 1950s， the distant hybridization between wheat and Thinopyrum á. L?ve has been developed in China， which was outstanding in the research of wheat disease resistance and the creation of new germplasm， on the basis of which a series of high yield and good quality wheat varieties have been cultivated. During the creation of Trititrigia Tzvelev， Thinopyrum intermedium （Host） Barkworth & D. R. Dewey and three species of Thinopyrum elongatum （Host） D. R. Dewey × ponticum （Podp.） Barkworth & D. R. Dewey） had the characteristics of cold resistance， drought resistance， saline-alkali resistance and resistance to a variety of wheat diseases and insect pests， so they have become the main parent sources of Trititrigia Tzvelev and had the widest range of application. This paper summarized the research progress of the creation and application of Trititrigia Tzvelev from five parts， in order to provide scientific basis for the research and utilization of Trititrigia Tzvelev and the innovation of wheat genetic resources.

Abstract:Wheat grain， with rich nutrition and various end-uses in markets， provides diets in over one-third of the global human population. However， with the increasing influence of biological and abiotic stresses， such as threats of diseases and pests， environmental damages of drought， high temperature and salinization， the sustainability of global wheat production is under increasing threats. In order to ensure the global food security supply and demands for high quality products， the desirable increases on wheat production and quality require to the constantly developing of new breeding methods and germplasm resources used for wheat breeding. In the past decade， significant progress on plant biotechnologies such as transgenic study and genome editing has been achieved， and gradually applied in wheat genetic improvement. To date， the efficient systems for wheat genetic transformation and genome editing have been established， in which the transformation efficiency for the model genotypes mediated by Agrobacterium is higher than 50% and the editing efficiencies of some target genes via CRISPR/Cas9 reach to 40%-70%. The genotype independency in wheat transformation and genome editing has been overcome almost. Some of wheat traits including disease resistance， stress tolerance， quality feature， yield potential， and growth and development regulation have been modified by using transgenic and gene editing methodologies； many new wheat genetic stocks showing disease resistances to powdery mildew， rusts， scab and yellow mosaic virus， tolerances to pre-harvest sprouting， drought and salt， low gliadin content， high gluten content， male sterility and haploid induction ability were created by the requirement of wheat improvement. This review aims to summarize the latest research progresses on transgene and genome editing in wheat， and to explore the current problems and possible solutions.

Abstract:In order to salvage and protect wild rice resources in Hainan Province， P.R. China， in November 2021， the Institute of Crop Science， Chinese Academy of Agricultural Sciences in cooperation with the Institute of Grain Crops， Hainan Academy of Agricultural Sciences carried out the investigation， ectopic protection and bacterial blight resistance of wild rice. In this study， 21 wild rice distribution sites in 17 towns of 11 cities/counties in Hainan province were investigated. It was found that 9 distribution sites were in an endangered state， 7 were damaged to varying degrees， and only 2 wild rice reserves are not disturbed and 3 distribution sites were slightly disturbed. 210 wild rice resources were collected and preserved in the National Wild Rice Germplasm Garden. In addition， the Philippine race 6 （PXO99）， which is highly aggressive with broad pathogenicity， was tested using artificial inoculation for bacterial blight resistance in this collection of 145 O. rufipogon Griff. and 47 O. officinalis Wall. ex G. Watt. Five accessions showing high resistance to bacterial blight were identified， which laid a rich material foundation for the research and breeding of resistance to bacterial blight in rice.

Abstract:From 2017 to 2018， the Fujian team of the “Third National Crop Germplasm Resources Census and Collection Action” carried out a comprehensive survey and collection of crop germplasm resources in 74 cities/counties in the Fujian province， P.R. China. A total of 148 rice landraces were collected， followed by the characterization of phenotypic traits and rice blast resistance. The rice resources collected from western and northern was far more than that in the southeastern coastal areas of Fujian. Rice landraces have been collected in areas from 4 meters to 1000 meters altitude. Phenotypic character identification showed that indica rice and japonica rice， the non-glutinous rice and glutinous rice were found with similar amount. Most germplasms showed the characters such as white brown， green leaf sheath， yellow apiculus and yellow glume， and wide ovum or oval grain shape. The collected rice landraces were rich in genetic variation of quantitative traits and have great potential for mining. Nine landraces including Xiayangjingdao， Luoyangjingdao， Danyangnuodao， Xiangchunyouzhong， Gongzhantong'anben， Hongmi， Hongkenuo， Heimi and Hongmizi， were identified with rice blast resistance. Based on the phenotype， we screened out six superior varieties of Xiangchunyouzhong， Hongmi， Hongmizai， 428， K28， Changlongshigu. Collectively， this study would provide a scientific basis for the effective protection of Fujian rice landraces.

Abstract:By taking the opportunity of the Third National General Survey and Collection Action of Crop Germplasm Resources， rice landraces were investigated and collected from different counties and cities in Anhui province， P.R. China. A total of 82 rice germplasms were collected and subjected for investigating their agronomic traits， rice blast resistance and grain quality. The results showed that rice landraces with glutinous or colored grain were abundant （glutinous rice： 56.1% of this collection； black or red rice： 34.2%）. Thirty-four landraces represented good agronomic traits such as longer panicle length， high grain number per panicle， high seed setting rate and high 1000-grain weight， 17 landraces showing excellent blast resistance and 6 landraces showing high grain quality. Furthermore， these genotypes of rice blast， chalkiness and fragrance in these excellent rice landraces were genotyped by functional markers. As a result， a few of landraces including Daoba， Jiagouxiangdao， Sanlicun， Zhuanghonggongmi， Lujiangxiaohongdao-1 and Changlinuodao were identified simultaneously showing good rice quality， blast resistance and yield traits. The elite landraces provided material basis for breeding new high-yield， high-quality and disease-resistant rice varieties.

Abstract:The flag leaf-related trait is important for the rice yield. The genetic mechanism of flag leaf length in rice was analyzed to lay a foundation in breeding of new varieties with ideal plant types and improve yield performance. In this study， the F₂ population was constructed， using and Balilla （Oryza sativa L. subsp. japonica S. Kato； short flag leaves； female） pollinated with the O. longistaminata A. Chev. & Roehr. （long flag leaves； male）. Based on the data of phenotype and genotype of the F₂ populations in three years， the QTL of flag leaf length and their genetic effects were analyzed. Ten QTL modulating flag leaf length were detected on chromosome 3， 4， 5， 7， 8， 9， 11 and 12 of rice. Among them， the QTL qFLL9-1 was identified as the major locus， while the other two QTL qFLL4-1 and qFLL11-1 were newly identified. We further generated a high generation backcross population BC₆F₂ targeting qFLL9-1， and demonstrated this locus with an important role in the population. These results will benefit for future fine mapping of this QTL modulating flag leaf length， and the development and utilization of O. longistaminata A. Chev. & Roehr..

Abstract:Foxtail millet （Setaria italica. L） is a vital crop that plants as food and fodder crop， with strong stress resistance and bundle of nutritional elements. Selenium （Se） is a component essential for human and animal cells， beneficial for plants growth and quality improvement. This study attempts to explore the ability of Se-responsive in foxtail millet and establish a corresponding evaluation system. We conducted the correlation analysis and principle component analysis based on 11 phenotypic indicators， including seedling height， leaf area， stem thickness， fresh weight of shoot， fresh weight of root， root length， total root length， root volume， apical number， shoot and root selenium content in 205 foxtail millet germplasm accessions. The membership function method was used to comprehensively evaluate the selenium responsiveness， and identify the genotypes showing Se efficient and Se deficient at the seedling stage. Furthermore， the enzymatic activities of superoxide dismutase （SOD）， peroxidase （POD） and catalase （CAT） in shoot were analyzed between Se efficient and deficient varieties. 205 foxtail millet varieties were grouped into five categories. There were 16 high Se-efficient responsiveness accessions， 45，60 and 66 with medium Se-efficient responsiveness accessions and 18 deficient accessions. Under 0.5 mmol/L Se treatment， the activities of SOD and POD were increased， whereas the activity of CAT was decreased. Collectively， the comprehensive index is more objective to evaluate the selenium efficient utilization of foxtail millet at the seedling stage， and the antioxidant enzymes activities of the plant are important for the responsiveness of foxtail millet to the Se treatment.

Abstract:To provide the theoretical basis for germplasm innovation and breeding in foxtail millet， disclosing the genetic variation of the key agronomic traits， exploration of the genetic factors affecting the content of amylose and yellow pigment in grain， and identification of the new lines with excellent performances become of significant interest. In this study， the recombinant inbred lines derived from ‘Nenxuan 15’ crossed with ‘Huangjinmiao’ were planted in the experimental field located in Dongyang county of Shanxi province， P.R. China （2020 and 2021）. Genetic variation analysis， correlation analysis， and regression analysis were carried out on two food quality traits （amylose and yellow pigment in grain）， and eight quantitative traits including plant height， panicle length， leaf area， stem diameter， panicle diameter， stem pitch number， single panicle weight and panicle grain weight. The significant differences on yellow pigment content， amylose content， leaf area， and panicle diameter between parents were observed. The RIL population lines showed comprehensive variations with （close to） normal distributions at these traits， showing two-way super parental separation. The coefficient of variation in each character ranged from 8.05% to 35.32%. According to the comprehensive analysis of the two-year data， the coefficient of variation on single panicle weight and grain weight per panicle were high， whereas the coefficient of variation on plant hight and amylose content were low. The content of yellow pigment was positively correlated with amylose， plant height， stem pitch number and grain weight， whereas it was negatively correlated with leaf area. Amylose content was negatively correlated with leaf area， stem diameter， and panicle length， whereas positively correlated with the stem pitch number. Furthermore， regression analysis showed that leaf area， plant height， and panicle length were the most important factors affecting yellow pigment content. Leaf area and panicle length had a negative effect on amylose content， whilst single panicle weight， panicle diameter， and stem pitch number had a positive effect on amylose content.

Abstract:The purpose of this study was to explore the phenotypic diversity of Gentiana rigescens Franch. ex Hemsl and establish a comprehensive evaluation method for excellent provenances of the species. The phenotypic datasets of 19 traits in 477 individuals from Yunnan province were collected. The Shannon-Wiener diversity index， principal component analysis， membership function， and partial least square were used to evaluate the provenances of G. rigescens Franch. The value of Shannon-Wiener diversity index（H'）of root， stem， and leaf traits of 477 individuals ranged from 1.59 to 2.06. At the several traits such as root diameter（H'=2.00）， stem diameter（H'=2.00）， root/biomass ratio（H'=2.02） and root water content（H'=2.06）， the highest H' values were observed. The dry weight of aerial part of plants showed the lowest H' value（H'=1.59）. The plant traits of G. rigescens Franch. which was from different geographical regions were significant differences（P<0.05）. Notably， the root yield traits value of G. rigescens Franch. from southern Yunnan was significantly higher than those in other distribution areas（P<0.05）. Based on the comprehensive evaluation value（D value）of phenotypes， the D value of 477 G. rigescens Franch. ranged from 0.50 to 2.45. The individuals collected from western and northwestern Yunnan（D=1.17±0.03）and southern Yunnan（D=1.19±0.37）had higher comprehensive evaluation value. Meanwhile， the D value of the individuals collected from central Yunnan（D=1.00±0.30）and southeastern Yunnan（D=1.00±0.32） were lower. The Yunxian population had the highest comprehensive evaluation value of plant（D=1.24±0.14）， and small differences in traits among individuals within the population（CV=11.02%）. It suggested that individuals of Yunxian population were excellent provenances. Through the analysis of PLS-R and PLS-DA， it was found that root fresh weight， root dry weight， dry weight of plant， branch number， fiber number， dry weight of aerial part， stem diameter and leaf length（VIP>1.00）were the key traits for the discrimination of good and bad provenances. And the environmental factors such as soil properties， precipitation during plant growing period and average temperature in the driest season were closely related to the high yield traits of G. rigescens Franch.（VIP>1.00）. The higher content of sandy and the lower content of clay in soil， drought and high temperature might lead to reduce of root fresh weight， dry weight and root number. The higher precipitation in April， May and November was observed with positive effects at root-relates traits.

Abstract:Jiangsu Crop Germplasm Gene Bank of China established in 2008 is hosting ca. 55，000 accessions from 54 crop species such as rice， wheat and corn. Considering the huge number of preserved accessions and diverse germplasm types， traditional management methods to independently record various workflow information and germplasm resource data would result in data/information redundancy and unfavorable handling for overall resource investigation and shared service. To meet the requirements of the germplasm bank， we deployed Java Web， distributed database， workflow， visualization and other technologies to design a full-process crop germplasm resource information management system. This system integrates the collection information， preservation and monitoring， reproduction and updating， identification and evaluation， and shared services. By standardizing and defining the data fields of germplasm resources， the management of germplasm resources information is standardized. By clarifying workflows and associated roles， standardized and traceable full-life-cycle management of germplasm resources is realized. Through data visualization technology， statistical analysis and data mining of germplasm resources data can be achieved. The system can greatly improve the working efficiency of germplasm resource bank management ensuring the safe preservation and effective sharing of germplasm resources.

Abstract:The management of agricultural germplasm resources is a basic work with many links， complex processes and large amount of information. According to the operational procedures and technical specifications for the warehousing and storage of germplasm resources， a set of germplasm resource information management system is required to guide the warehousing and storage process of germplasm resources in a standardized manner， track the inventory of germplasm resources in a timely manner， and manage the property data information of inventory resources. The application of user oriented conceptual data models and methods to the standardization of crop germplasm resource information management， and the reconstruction of data models and the development of crop germplasm resource management systems are of great significance for promoting the integration of germplasm resource information and improving the efficiency of germplasm resource protection and sharing. Aiming at the construction of Shanghai Crop Germplasm Resources Information Management System， this paper introduces the overall design， data specification， data model， business process and system application of the system in detail. The character data module is the biggest improvement of this system， which changes the previous model of separating the physical management of germplasm resources from the data information management of germplasm resources， and puts the physical and data into the same system for management， It is convenient for managers to fully control the physical status and information status system of the resources in this library， realize the sharing of crop germplasm resources in Shanghai， and provide germplasm resource data services and technical support for social related agricultural workers. The purpose is to provide reference for the construction of crop germplasm resource information database.

Abstract:In order to clarify the SFB gene diversity in Malus Mill. and the distribution frequency of each sequence haplotype in ecological populations， 82 Malus Mill. germplasm resources including the cultivated apples （i.e. Kuihua） and wild resources （i.e. Malus sieversii（Ledeb.） M. Roem.） were used. The genotyping was conducted using three gene-specific primer combinations. PCR amplification using leaf DNA produced a single SFB gene fragment in all materials. Sanger sequencing of PCR products revealed these fragments belonged to five different SFB genes， corresponding SFB₁， SFB₂， SFB₃， SFB₇and SFB₉ based on GenBank homology comparison. At the same time， the distribution frequency of SFB gene in different ecological population was analyzed. The frequencies of different haplotypes in populations were different， and the highest frequency of SFB₃ was 43.90%， followed by SFB₁ （39.00%）. The intraspecific and interspecific frequency of the same SFB gene was also different. In addition， the phylogenetic tree analysis showed that Malus sieversii （Ledeb.） M. Roem. was related to the domestication and origin of Malus turkmenorumJuz. & M. Pop. and apple cultivars.

Abstract:In order to investigate the role of superoxide dismutase （SOD） gene family members in the self-incompatibility response of Camellia oleifera Abel， three family members CoCSD， CoFSD and CoMSD were isolated by RT-PCR. The CDS sequences of CoCSD， CoFSD and CoMSD were 660， 813 and 693 bp in length， encoding for 219， 270 and 230 amino acids， with a molecular weight of 22.49， 31.18 and 25.51 kDa， respectively. Structural analysis revealed that three proteins were hydrophilic without transmembrane domain and signal peptide （non-secretory proteins）， and all contained 21 phosphorylation sites. Both CoCSD and CoMSD are stable， while CoFSD is an unstable protein. The secondary structure of CoCSD is mainly composed of irregularly coiled and extended chains， while the secondary structure of CoFSD and CoMSD is mainly composed of α-helices and irregular coils. The three proteins were assigned to three categories in the phylogenetic tree， whereas all were clustered on the same branchlet with the corresponding proteins of tea tree and had high sequence homology. The SOD enzyme activity in self-pollinated pistils was overall higher than that in cross-pollinated pistils， but the expression of CoCSD， CoFSD and CoMSD was highest before pollination and was inhibited by both self and cross-pollination treatments. The results of this study provide a basis for the subsequent in-depth investigation of the biological functions of C. oleifera Abel SOD genes， and also provide a reference for revealing the mechanism of self-incompatibility in C. oleifera Abel.

Abstract:Soybean is a phosphorus-loving crop， whereas phosphorus deficiency can affect soybean growth and development finally resulting in yield loss. The grain weight per plant of soybean is a quantitative character， which is an important indicator for identifying soybean tolerance to low phosphorus. At present， most studies are still in the stage of QTL mapping， so it is particularly important to discover more regulatory genes and excellent allelic variations in order to promote the analysis of the regulatory mechanism of soybean tolerance to low phosphorus and its breeding utilization. In this study， 395 soybean germplasm resources were used to conduct genome-wide associated study （GWAS） and preliminarily predict candidate genes by using grain weight per plant under low phosphorus and relative conditions as identification indicators for low phosphorus tolerance traits， combined with high-density SNP markers. The results showed that the tolerance to low phosphorus was significantly different among different soybean germplasms. The grain weight distribution per plant of normal phosphorus was 0.49 ~ 14.43 g， the grain weight distribution per plant of low phosphorus was 0.05 ~ 5.35 g， and the relative grain weight distribution per plant was 0.04 ~ 0.98. The coefficients of variation of the three were all higher than 50%. Through cluster analysis， 4 landraces such as Yapoche（ZDD00219） and Caizhongpu（ZDD00163） and 16 cultivars such as Jinyuan 1 （ZDD00383） and Jiyu 48（ZDD23714） were screened as phosphorus efficient soybean germplasms. GWAS identified 32 SNP loci significantly associated with low phosphorus tolerance of soybean， including 23 SNP loci associated with single plant grain weight under low phosphorus and nine SNP loci associated with relative single plant grain weight. Two candidate genes were proposed by LD block analysis， including a WRKY DNA binding domain gene that was detected with specific expression in roots， and a pyridoxal phosphate phosphatase gene that was detected with specific expression in root hairs.

Abstract:Sorghum is the fifth most important cereal crops in the world and shows strong tolerance to low-fertility soil and drought. Nitrogen is one of the three essential nutrients which ensures stable and high crop yield. The nitrogen signaling pathways in sorghum remains largely unknown. Deciphering the nitrogen deficiency inducible genes will help to analyze the molecular pathways involved in sorghum nitrogen absorption and utilization. A member of MYB-related transcription factor family， SbMYB-like （Sb03g030330） was cloned based on the global gene expression profiles of sorghum seedlings under nitrogen， phosphorus， and potassium deficiency conditions. SbMYB-like was found being inducible by nitrogen deficiency in shoots， and its deduced protein SbMYB-like was predicted to be localized in the nucleus. qRT-PCR analysis showed that the transcripts of SbMYB-like were lower in roots， stems and flowers， whereas abundant in leaves. Phylogenetic tree analysis indicated that SbMYB-like was closely grouped with its homologs in maize and Brachypodium P. Beauv.， and both homologs were inducible under nitrogen deficiency condition by qRT-PCR. The SbMYB-like coding sequence from sorghum BTX623 variety was isolated and transformed into Arabidopsis Heynh. driven by a constitutive promoter. The growth parameters of SbMYB-like over-expressing plants under nitrogen and phosphorus deficiency conditions were measured. The results showed that SbMYB-like was involved in root elongation and flowering independent of the environmental nitrogen levels. Collectively， this study provided basic data for analysis molecular mechanism of sorghum response to nitrogen deficiency.

Abstract:Flax is a special oil crop cultivated in the northern China and rich on unsaturated fatty acids. Breeding of high linolenic acid varieties and high linoleic acid varieties is the main objective in flax quality breeding programs. Molecular marker assisted selection can improve flax breeding efficiency and shorten breeding duration. In this study， analysis of fatty acid phynotypic datasets gained from a natural population of 246 flax accessions， together with the construction of genotyping population， the KASP genotyping and verification of linolenic acid and linoleic acid-related SNP loci were carried out. We obtained the following results mainly including： （1） The linolenic acid was significantly negatively correlated with other components， and especially the negative correlation between linolenic acid and linoleic acid was the highest ； （2） Linolenic acid and linoleic acid-related SNP genotyping populations were established consisting of 87 accessions， which included 49 high linoleic acid （≥54%） accessions， 36 low linoleic acid （≤13.5%） accessions， and two accessions No.8 （CH-89） and NO. 254 （CI637PI91037） simultaneously showing high linoleic acid and low linolenic acid； （3） Seven SNPs associated with particular traits were validated， i.e. three SNPs g6-6229142， g10-19305239， and g9-18961021 were significantly associated with linolenic acid， four SNPs g6-19208888， g9-14900088， g15-22369840， and g2-7680441 were significantly associated with linoleic acid； （4） A coincidence of the 7 SNP loci was detected by high-throughput sequencing and KASP genotyping， confirming the effectiveness and accuracy of the KASP genotyping.

Abstract:In recent years， the global low temperature extreme weather occurs frequently， destabilizing the rice production. Low temperature is a factor that restricts the expansion of rice planting areas. Therefore， the identification and cloning of genes related to low-temperature and the elucidation of their molecular mechanism might lay a theoretical foundation in low-temperature molecular breeding of rice. In this study， a mutant lta1 （low temperature albinism 1） showing low temperature leaf albinism was identified from the chemically-induced mutagenesis mutant library of rice Nipponbare. Compared with the wild type， the lta1 mutant displayed albino leaves with significantly reduced chlorophyll content， and abnormal chloroplast structure development at 20 ℃， whereas there was no significant difference between lta1 and wild type at 30 ℃. Through map-based cloning， the mutant gene lta1 was allocated between the insertion/deletion markers LTA1-3 and LTA1-7 on the short arm of chromosome 3， with a physical distance of 132 kb. Based on the rice gene expression database， 17 candidate genes in the region were annotated， and the proteins of six candidate genes were proposed to be localized in chloroplasts. Real-time fluorescence quantitative PCR showed that most chloroplast encoding genes were observed with lower transcripts in the mutant， while most chlorophyll synthesis related genes did not change significantly. Our results provide a possibility for further cloning the LTA1 gene and revealing the mechanism of chloroplast development in rice under low temperature.

Abstract:The okra fruit is easily lignified， whereas the fruit lignification would decrease the commercial value. In order to explore the aging mechanism of okra fruit， two cultivars， Z06 （easy to age）， and Suyoukui 3 （not easy to age）， were used for physiological indicators quantification and transcriptome sequencing at three developmental stages. The differences in fruit texture between cultivars or at different developmental stages was mainly caused by the accumulation of lignin， while cellulose and protopectin were also found with positive effects. The differentially expressed genes （DEGs） of the same cultivar at different fruit development stages were significantly enriched in the phenylpropane biosynthesis and secondary metabolite biosynthesis pathways. While the DEGs between the cultivars were found with enrichments in the phenylpropane biosynthesis pathway， the photosynthesis and photosynthesis antenna protein pathways. During the hardening stage of okra fruit， the gene PAL was found as key regulator that affected lignin accumulation. The SUS3 gene contributed predominantly to the accumulation of cellulose， and the down-regulated expression of the BGLU gene was also an important factor in promoting the accumulation of cellulose. Two genes GAUT6 and SUS6 largely contributed to the accumulation of protopectin， but most of the PME and PG genes had a negative contribution to the accumulation of protopectin. Lignin synthesis-related genes PAL6， PAL5， PAL1， CCR2， CYP84A1， CYP73A12， and photosynthetic pathway-related genes PSBP2 and CAB1R were important genes that affected the texture differences of two cultivars.

Abstract:Hort16A， a variety of Actinidia chinensis Planch.， is highly popular among consumers due to its high nutritional value. However， this variety is sensitive to frost and susceptible to ulcer disease and branch rot. The response mechanism of yellow-fleshed A. chinensis upon cold temperature remains still unclear. In this study， transcriptome analysis of yellow-fleshed kiwifruit under low temperature stress was performed to provide theoretical references for understanding the mechanisms involved and subsequent studies on cold resistance. The cold-resistant tetraploid materials and the plants treated at low temperature （0 ℃） for 5 h were used as the experimental group， and those not specially treated at room temperature were used as the control group， and the samples were taken for transcriptome sequencing using Illumina NovaSeq 6000 platform. GO enrichment analysis revealed 1013 differentially expressed genes， which were enriched into three categories： molecular function， cellular component， and biological process. KEGG enrichment analysis showed that 410 differentially expressed genes were enriched in the three main functions of plant hormone signal transduction， MAPK signaling pathway-plant， starch and sucrose metabolism， and 89 other metabolic pathways. Nine genes related to cold resistance in yellow-fleshed kiwifruit， including PYL， PSR， TPS， GH3， SAUR， and PP2C， were tentatively identified. The results of this study can provide theoretical references for further studies on the response mechanism of tetraploid yellow-fleshed kiwifruit to low temperature stress.

Abstract:The variation coefficient analysis， genetic diversity analysis， correlation analysis， principal component analysis and cluster analysis of 647 island cotton germplasm resources were carried out in order to screen more diverse types of island cotton germplasm resources for parent selection and variety breeding in the future. The variation range of quantitative index of 647 sea island cotton germplasm resources was 2.4608%~36.4320%， indicating the rich diversity among sea island cotton germplasm resources. The number of stem hairs， leaf color， leaf hairs， petal basal spot size， main stem hardness， fruit branch type and style length of island cotton germplasm resources were variable， and these external descriptive traits could be directly used for the improvement of plant morphology. Genetic diversity analysis of quantitative indicators showed that the diversity of indicators reflecting fiber quality was more abundant than that reflecting yield， and germplasm resources could be used for improving fiber quality and maturity. Correlation analysis revealed a significant correlation between different quantitative traits. Among them， the first fruit branch node was significantly negatively correlated with the average length of the upper half， the uniformity index and the breaking strength， the sub-index was significantly negatively correlated with the micronaire value， and the lint percentage was significantly negatively correlated with the average length of the upper half. The above correlation is consistent with previous research results on upland cotton， The complicated interaction mode implied a comprehensive evaluation by integrating multiple datasets in germplasm innovation. The principal component analysis showed that the cumulative contribution rate of the first five eigenvalues reached 75.761%. The first principal component was related to fiber quality， the second principal component was related to seed cotton yield， the third principal component was related to elongation， the fourth principal component was related to maturity， and the fifth principal component was related to lint percentage. When the genetic distance was 10， the germplasm resources were divided into 6 groups by cluster analysis. The comprehensive performance of cluster II was better. In actual breeding， targeted selection and improvement can be carried out according to breeding objectives.

Abstract:This paper describes a new type of fresh corn-waxy corn with sweet taste and the representative varieties. Through the innovation and improvement of waxy corn germplasm， all the grains of the waxy corn with sweet taste are waxy with 12% brix or higher on average sugar content during the suitable harvesting period， which is significantly higher than that of ordinary waxy corn. This type of corn is sweet and forms a special taste quality of “waxy with sweet”. In 2011， fresh corn innovation team of Beijing Academy of Agriculture and Forestry Sciences initiated the program of “waxy corn with sweet taste” germplasm innovation and variety cultivation. Using innovative and integrated breeding methods such as “high-quality， large-group， strict-selection”， “individual plant test”， and “elite lines aggregation”， and a large number of field phenotype identification and evaluation of grain sugar content and taste quality， we produced the waxy corn backbone inbred line ZN3. Using ZN3 as parent， a waxy corn with sweet taste variety Jingkenuo768 was released with 14% brix on the sugar content of fresh kernels. Jingkenuo768 shows the overall advantage， such as high sweetness in kernels， good taste quality， high and stable yield， multi-resistance and wide adaptability， long harvest periods， etc.， and has been rated in list of “Top Ten Excellent Variety in China”. Jingkenuo768 passed the national examination at four ecological zones in 2021， suitable for planting in the national fresh corn ecological zones. The waxy corn with sweet taste will lead the direction of waxy corn development in the future.