Abstract:Synergistic evolution theory of crop germplasm resources and cultural environments is about the interference, interaction, and interpromotion between each other. On one hand, culturing different crops in a specific environment will lead to the formation of corresponding dietary traditions and cultural environments, on the other hand; dietary traditions and cultural environments will in turn have a profound influence on the formation of crop germplasm resources and might even lead their evolution. The genetic basis of this theory is that after the natural hybridization or mutations of the crops occurred during the processes of their dissemination and improvements, they are targeted and fixed under the artificial selection of the specific cultural environments, the frequency of the recombinant or mutant genes continues to accumulate and increase in the population, and finally form new crop and their germplasm resources adapted to the specific cultural environments. Modern crop breeding is also guided by this theory to a certain degree, which greatly promoted the evolution processes of crops and their germplasm resources. Taking the Customary System of Chinese traditional dietary culture as an example, this paper investigated the impact of dietary tradition on the evolution of crop germplasm resources from four aspects: waxy germplasm, steaming preference, rich varieties of vegetables and fruits, and use of whole-plant material. In view of the protection and utilization of crop germplasm resources in the future, suggestions were proposed, including paying attention to farmers’ rights and original habitats of crops, and following the basic law of “if there were character differences and genetic mutations, then select” to accelerating the landrace, crop wild relatives preservation and utilization, genomics research, and crop improvement as well as their positive evolution.

Abstract:The phenotype, as outcome of genotype that interplays with environmental factors, includes different traits such as architecture, growth stage, yield characters, quality, and resistance to biotic and abiotic stresses. After long-term natural variations in eco-system as well as domestication and cultivation in agricultural eco-system crop germplasm obtained rich genetic and phenotypic diversity, as the fundamental basis in breeding for new varieties. It is of interest to explore and understand the phenotypic diversity by scientific and systematical identification and evaluation. Identifying elite germplasm resources that showed drought and heat tolerant, disease and pest resistant, high efficient use of water and fertilizer is absolutely important to breed new varieties with environmental adaptability under global climate change. Testing for phenotypic variations under controlled environment at multiple locations for years is desirable and highly recommended. The methods for identifying phenotypic variations are conducted in the fields, facilities, instruments and with person sensory. The identification of crop germplasm traits, which were surveyed at one environment (locus) with expected low-throughput and low accuracy, has been popularly performed at multi-environments with high-throughput and precise characterization. By taking advantage of rapid development on technologies of multi-Omics, artificial intelligence, image recognition and analysis, researches on phenotypic traits of crop germplasm resource will step for a new stage, valuable for crop breeding in the future.

Abstract:Survey and collection are the foundational work in the research field of crop germplasm resources, and enable the performance of conservation, basic research, evaluation and utilization. Survey is able to obtain the information of geographical distribution, ecological types, botanical features and agronomic characteristics of germplasm resources, and this information is valuable in basic studies of crop origin and evolution as well as conservation biology. The collected germplasm resources might contain the boarder genetic diversity which is of interest in discovery of high value genetic resources valuable for agricultural utilization. This paper reviews the history of field survey and collection activities of crop germplasm resources, followed by introduction of the theoretical basis (i.e. disequilibrium distribution, crop origin center and germplasm resources distribution, human civilization and crop origin) of investigation and collection. For providing a practical guideline, this paper introduces the detailed methods and notes in the survey and collection, and proposes the future development in the field of crop germplasm resource survey and collection.

Abstract:Cotton is a pivotal industrial crop, mainly cultivated for producing natural textile fibers. Considering its versatile capacity, cotton industry occupies indispensable strategic position at the national level. With the intensified greenhouse effect, the frequent and continuously occurring high temperature weather severely limited the cotton production in China and in the world. In the last decade, research groups have made visible progress in investigating the response of cotton to high temperature stress in order to breed high temperature tolerant cultivars to reduce yield loss. This review summaries the advances mainly including: (1) effective evaluation systems of high temperature tolerance performance in cotton; (2) genetic, physiological and biochemical mechanisms of high temperature tolerance in cotton; (3) high temperature tolerant germplasm innovation of cotton and breeding practice. We expect to raise questions and suggestions for cotton high temperature tolerance research, germplasm innovation and breeding practice in future.

Abstract:The common wheat (Triticum aestivum L.) is an allohexaploid crop species originating from the distant hybridization between the cultivated tetraploid wheat (T. turgidum) and the wild diploid grass Aegilops tauschii Cosson. Common wheat inherits the high-yielding potential of tetraploid wheat, extends potential to make diverse food products and has broad adaptability to environments afforded by the incorporation of D genome. Different from diploid crops, common wheat hosts three sub-genomes harboring a large number of repetitive genes and shows a strong capacity of genomic buffering and plasticity. Thus, allelic variation at a single locus often results in an insubstantial effect during wheat improvement. The genetic diversity among three sub-genomes of common wheat was not symmetric, and D sub-genome diversity was the lowest. By simulating the origination process of common wheat, synthetic hexaploid wheat can be produced as a bridge to incorporate the genetic variations of Ae. tauschii and tetraploid wheat into common wheat. In contrast to common wheat, synthetic hexaploid wheat harbors abundant favorable variations and owns new expression characteristics at transcriptome level, which provide novel genetic basis for breeding. Although synthetic hexaploid wheat is to be placed with great expectation, the utility remains very limited in wheat breeding. Cytological instability and poor comprehensive agronomic performance are disadvantaging in breeding utilization. Optimization of the crossing and selecting strategies will promote the application of synthetic hexaploid wheat in common wheat breeding.

Abstract:Maize (Zea mays L.) is ranking first in total yield production of the crop species in China, whereas this important crop is sensitive to salt stress. As the salinization of farmlands has become one of the major environmental stresses that decrease maize yield and quality, it is important to study the mechanism of salt tolerance and thus facilitate the development of salt-tolerant maize. It’s known that high-salt concentration can damage maize plant mainly by causing osmotic stress and ion toxicity. In recent years, several salt-tolerant QTL or genes which are involved in regulating either ion homeostasis or osmotic tolerance, have been identified by GWAS and/or QTL analysis, and their functional mechanisms have been investigated. Here, we review recent progress on deciphering the mechanisms of salt tolerance in maize.

Abstract:Ear rot is one of the most devastating diseases in maize production in China, which seriously affects the yield and quality of maize and threatens the health of humans and animals. Breeding and using excellent ear rot resistant varieties is the most economical and effective measure to prevent and control maize ear rot. Using silk channel inoculation, 346 maize inbred lines at home and abroad were identified and evaluated for resistance to Fusarium ear rot (FER) and Gibberella ear rot (GER) (caused by Fusarium verticillioides and F. graminearum, respectively) at two sites in Changping, Beijing and Sanya, Hainan. A comprehensive analysis of the data from the two sites showed that there were 1, 43, 106, 147 and 49 accessions exhibiting high resistance (HR), resistance (R), moderate resistance (MR), susceptibility (S), and high susceptibility (HS) to FER, accounting for 0.3%, 12.4%, 30.6%, 42.5%, and 14.2% of the total 346 materials, respectively, and there were 10, 32, 55, 79, and 170 accessions exhibiting HR, R, MR, S, and HS to GER, accounting for 2.9%, 9.3%, 15.9%, 22.8%, and 49.1% of the total 346 materials, respectively. Forty-one maize inbred lines exhibited HR, R, or MR to both FER and GER. Among them, line 15-TL-1224 exhibited HR to both FER and GER, lines T351-1 and 18-QTL-25 exhibited HR to GER and R to FER, and 3 lines exhibited R to both FER and GER, which were all precious resources resistant to ear rot. The correlation analysis of FER and GER resistance among the above 41 resistant accessions and 144 susceptible germplasms was conducted. The correlation coefficient between FER and GER resistance among the 41 resistant accessions was 0.24, while that among the 144 susceptible germplasms was -0.16. Using 40 pairs of polymorphic SSR primers, 183 alleles (Na) were amplified in the 41 resistant lines, with polymorphic site percentage (PPB) of 100.00%. The average number of alleles (Na), effective allele number (Ne), Nei's gene diversity (H), and Shannon's information index (I) were 3.7556, 7.6923, 0.6596, and 1.4458, respectively. The average polymorphic information content (PIC) was 0.326, varying from 0.0513 to 1.0000 for each marker. Using UPGMA cluster analysis, the 41 resistant accessions were divided into 7 subgroups, namely PB, Lan, unknown, PA, LRC, BSSS, and TSPT, which exhibited high genetic diversity among the 41 inbred lines. The PA subgroup contained the most numerous resistant germplasms. The results would provide guidance and reference for the selection and utilization of resistance sources in breeding.

Abstract:In order to detect the resistance genes of germplasm resources against barley stripe disease and understand their genetic diversity, in this study 91 barley accessions were inoculated with barley stripe disease pathogen by sandwich method, followed by the genetic diversity analysis using 31 polymorphic SSR markers. Of them, four accessions were identified to be complete resistance (free of diseased symptom), 6 highly resistant, 33 resistant, 42 susceptible and 6 high susceptible. Genotyping by 31 SSR markers disclosed 238 alleles, with a mean of 7.677 alleles in each of markers and the range of 2 to 19 alleles. The frequency of major loci ranged from 0.236 to 0.951, with an average of 0.394. The gene diversity index ranged from 0.094 to 0.871, with an average of 0.667. PIC ranged from 0.091 to 0.860, with an average of 0.613, while GS ranged from 0.103 to 1.000, with an average of 0.522. This collection were divided into three groups at the genetic similarity coefficient level of 0.783, each containing 86, 2 and 3 accessions, respectively. The population structure analysis suggested three groups, each including 47, 33 and 32 materials, respectively. 97.80% of 91 genotypes had Q value greater than 0.6. Gained from disease resistance identification and genotyping, this study provided reference for selecting parental lines in breeding of barley leaf stripe resistant varieties.

Abstract:In this study, 307 accessions of rice (Oryza sativa L.) landraces from different altitude ecological regions in Yunnan Province were used as experimental materials to evaluate the cold tolerance in four growth stages, including the germination stage, the sprout stage, the seedling stage, the booting and flowering stage. The results showed that the cold tolerance in different growth stages for Yunnan rice landraces was significantly or extremely significantly positively correlated with the altitude of the ecological region where they were distributed. In other words, the cold tolerance of Yunnan rice landraces was closely related to the altitude of the ecological region from where they were derived. The cold tolerance in different growth stages for rice landraces distributed in high-altitude ecological regions was significantly stronger than that of rice landraces distributed in low-altitude ecological regions. There was a significant or extremely significant positive correlation among the degrees of cold tolerance in different growth stages, indicating that cold tolerance in each growth stage can be used as indirect indicators for cold tolerance evaluation. Through the identification and evaluation of cold tolerance in four growth stages were screened out 20 landraces (including Lengshuigu, Cizhonghuanggu, Jiegunuo, and Longchuannuo) with grade 1 cold tolerance in germination stage and seedling stage, 9 landraces (including Xiaoheigu, Qitougu, and Yunnangu) with grade 1 cold tolerance in germination stage and booting and flowering stage; 18 landraces (including Bayuenuo, Landigu, and Aolenggu) with grade 1 cold tolerance in seedling stage and booting and flowering stage, and the landrace Aijiaoxi with grade 1 cold tolerance in germination stage, seedling stage, and booting and flowering stage. These excellent germplasms with very strong cold tolerance are of great value and could be used for breeding improvement and new gene discovery for cold tolerance in multiple growth periods.

Abstract:Sugar beet is a widely-cultivated sugar-producing crop with vital significance in the sugar industry. Unlocking its germplasm resource might provide elite parental lines applicable for Sugar beet breeding. In this research, the diversity on five quality traits, 18 agronomic traits and three resistance traits in 205 Sugar beet germplasm accessions collected from Northeast China were analyzed, followed by the correlation, principal component and cluster analysis. The correlations between the quality traits of Sugar beet were observed, and the coefficient of variation varied from 6.104%-33.830% (i.e. the coefficient of variation of sodium content was the largest). Moreover, the diversity analysis of 18 agronomic showed abundant genetic variation, and a variation coefficient of over 30% at leaf traits was observed. Furthermore, we deployed the concept of recoverable sucrose content to evaluate the quality of Sugar beet, and used it to compare and screen with root yield and impurity index, thereby obtaining 12 high-yield varieties with high-quality. In addition, through cluster analysis and principal component analysis of the agronomic traits, the germplasm tested was divided into four categories according to traits, and six principal components explaining the meaning of traits were obtained. The results showed that the variation coefficients of leaf traits were all over 30%. Besides, principal component analysis showed that the contribution rates of the first 6 components reached 62.50%. Among them, The first principal component is mainly related to the growth factor of Sugar beet, the second principal component is mainly related to the young plant biomass factor of Sugar beet, the third principal component is mainly related to the traits of Sugar beet roots, and the fourth principal component is mainly related to the growth and development of them, the fifth principal component is mainly related to Sugar beets’ marker traits, and the sixth principal component is mainly related to the nutrient transport factors. Then, the cluster analysis revealed that groups 2 represented by 94211 and T30BDXIJ had the high 100-seed weight of young plants, large number of vascular bundles, mixed colors of hypocotyls, and thick petioles, which means they were the germplasm resources with excellent traits and could be used as a high-quality material for improving sugar beet biomass traits. The germplasm was classified for resistance according to the disease index in order to screen the comprehensive disease-resistant varieties. Based on the disease index, five germplasms with high resistance to spot disease and root rot resistance (8216M152, H1352, F86421, 7909, H133) were screened out. The identified high-quality germplasm are valuable and laythe foundation for future breeding high-yield and disease-resistant varieties.

Abstract:The evaluation of fiber yield related traits in ramie can provide scientific basis for molecular marker selection breeding and elite germplasms on genetic improvement of ramie varieties with high fiber yield. In this study, 298 ramie germplasm accessions from different sources were used for the field trials at three seasons, followed by data collection, frequency distribution histogram analysis, coefficient of variation analysis, correlation analysis, principal component analysis and cluster analysis. A normal distribution at six traits related to fiber yield was observed, with the variation coefficients ranged from 16.33% to 69.00%. The maximum variation coefficient (69.00%) for dry fiber yield was observed in June 2020. Except variation of stem diameter was detected with the minimum coefficient (16.33%) in August 2020, the coefficient of variation of dry fiber yield, fresh bark weight, stem bark thickness, stem length and bast stripping percentage were all higher than 20%, indicating that 298 ramie germplasm resources had rich genetic diversity. Correlation analysis showed that stem length positively correlates with all the other traits. The positive correlation of stem diameter and stem bark thickness in comparison with fresh bark weight and dry fiber yield was detected, and significant positive correlation between fresh bark weight and dry fiber yield was detected, and significant positive correlation on dry fiber yield and bast stripping percentage was detected. The improvement of stem length and dry fiber yield correlates with bast stripping percentage. Principal component analysis revealed two components with the cumulative contribution rate of 82.38%, 71.01% and 79.25% at three seasons. The dry fiber yield had the greatest effect, and the bast stripping percentage had the second greatest effect, indicating that both traits could be used as important indicator to evaluate whether the ramie germplasm resource fiber yield traits were excellent. Cluster analysis suggested three groups in each season, and the 6 traits of groupⅠwere all excellent. This study identified 14 high-quality varieties such as 7469, J0501-307, Chuanzhu10, TG5, Donganyuanma 294, Xinyangma, and Guangxihongjianma, as candidate parents or core germplasm in breeding.

Abstract:Colorful-pericarped rice is an important component of rice germplasm resources. It could be the key material for satisfying the market demand for colored rice. An accession of rice that produced some seeds with green pericarp was found during our investigation of the collected rice germplasm resources. A stable line of green rice was obtained by multigeneration selfing, and was named LM8. It was highly light-sensitive, and was easily crossed with Asian cultivated rice. When grown in Guangxi, it produced 19 effective tillers per plant, with an erect, compact habit, and with the plant height, flag leaf length, flag leaf width and panicle length of 117.7 cm, 32.1 cm, 1.1 cm, and 22.5 cm, respectively. LM8 had very small, ellipsoidal seeds with 1000-grain weight of 8.73 g, 5.76 mm in length and 2.09 mm in width, rich in fat and essential trace elements needed by human body. The evolutionary tree demonstrated that LM8 was of AA genome type and grouped with Asian cultivated rice. Having some wild characteristics in its initial discovery, such as the presence of awn, strong shattering of seed, and hard deep-brown hull, LM8 could be a kind of weedy rice. This study would not only promote the establishment and improvement of genetic development and regulation network of rice pericarp color, but also provide the genetic material for innovation breeding of green rice varieties, and therefore satisfy the diverse consumer preferences and play a positive role in rural revitalization.

Abstract:In this study, the biological characteristics and breeding applicability of five indica-compatible japonica germplasm (Minghui413, Minghui1616, Minghui1707, Minghui512 and Minghui 509) have been studied, which will provide theoretical reference for the future breeding of indica-compatible japonica germplasm and the heterosis utilization of the indica-japonica inter-subspecific hybrids. Five germplasm showed longer growth period, moderate plant height, erect panicle type, small panicle, dense grain setting, increased effective panicles per plant, high setting percentage and big grain size. The analysis using the Cheng’s indexes showed that Minghui413, Minghui1616, Minghui1707 and Minghui512 belonged to japonicalinous, while Minghui509 belonged to japonica. In addition, these germplasm showed a good indica compatibility. For instance, the seed setting rate of F1 by crossing with the two-line indica sterile line was >75% with a highest value of 89.80%. These germplasm are able to restore the fertility of indica CMS lines (WA type, YS type, and K type), and the seed setting rate was >80%. Moreover, the flag leaves of the five germplasm accessions could maintain a higher photosynthetic rate in the later period of growth and breeding, beneficial to the filling and fullness of grains. Except DSH (Duration from seeding to heading), plant height and 1000-grain weight, the heterosis of five indica-compatible japonica germplasms showed competitive performance in panicle length, effective panicle per plant, total grain number per panicle, seed setting rate, number of primary branch rachis and number of secondary branch rachis per panicle. Among them, panicle length, primary branch rachis number, secondary branch rachis number and total grain number per panicle all showed more than 10% competitive advantage. Indica-japonica hybrid rice Hualiangyou3716 and Huanliangyou3707, developed from two-line indica sterile line Hua1037S and the indica-compatible japonica germplasms Minghui1616 and Minghui1707 were registered and released by Fujian Provincial Crop Variety Appraisal Committee. The yield production of these two varieties was significantly higher than that of the control. Therefore, this study reported the five indica-compatible japonica germplasm accessions, which showed good indica compatibility and broad restoring spectrum with a good prospect in the subspecies heterosis utilization.

Abstract:The wheat lines derived from wide cross between common wheat and Agropyroncristatum contain multi-grain genetic characteristic. The multi-grain wheat line Pubing10969 as well as several major wheat varieties promoted in the Huang-huai winter wheat production region have been selected as plant materials in this study to better understand the developmental process during which this multi-grain characteristic has formed. In this study, the dynamic developmental processes of floret differentiation, degeneration and seed formation between distinct wheat varieties were compared and analyzed by anatomy and statistical methods, to provide theoretical principles for the application of multi-grain genotypes in plant breeding and to uncover the mechanisms underlying multi-grain characteristic. The analysis of variance (ANOVA) results of agronomic traits showed that the multi-grain characteristic of Pubing 10696 was mainly caused by the improved grain/spikelet number per spike, and it did not negatively affect the 1000-grain-weight. The anatomy results of developmental characteristics of plant immature spikes at different stages demonstrated that during panicle differentiation, the initiation and duration time of Pubing10696 were much earlier and longer, respectively, than the check varieties. Besides, the differentiation and degeneration speeds of floret developmental process of Pubing10696 were more rapid and slower than the others, leading to the significantly increased number of florets developed into the tetrad stage. These characteristics were the main causal factors of increased number of florets and more grains developed. To sum up, the developmental characteristics of the immature spikes and florets of Pubing10696 were the determining factors for its multi-floret and multi-grain agronomic traits.

Abstract:It is important to uncover the genetic mechanism of lodging-resistance, and to explore the lodging-resistance genes and select the lodging resistant varieties of wheat, for ensuring food production safety in China. ‘Zhou 8425B’ is an important wheat backbone parent in Huang-Huai region of China with excellent agronomic characters, from which derived varieties with good lodging-resistance. This study explored the lodging-resistance associated loci in ‘Zhou8425B’ and 61 derived varieties, based on genome wide association analysis by 50 K SNP chip and eight lodging reaistance related traits. A total of 226 significantly associated SNP markers were detected, which were distributed at 42 loci on 21 chromosomes, accounting for 7.0%-18.8% of the phenotypic variations, respectively. Among them, 14 loci were consistent with the previously reported loci, and the other 28 loci were new. In addition, three candidate genes encoding E3 ubiquitin ligase, cellulose synthase and cell division protease were found at the significant sites. This study is of great significance for breeding lodging resistant wheat varieties.

Abstract:Waterlogging has become one of the major abiotic stress to a variety of plants including maize in southern China. Investigating the biological characteristics of waterlogging tolerance, creating new waterlogging resistant maize germplasm and cultivating new waterlogging resistant maize varieties are the most economical and effective way to reduce the loss of maize yield. In this study, multiple evidences showed that maize BMY (Baimaya) was more waterlogging tolerant than maize B73. At the phenotypic level, SPAD (soil plant analysis development) value, root and shoot fresh weight, root and shoot dry weight, seedling height, number of adventitious roots and root length of BMY were significantly higher than those of B73 under waterlogging stress. After 28 days of waterlogging, the average survival rate of BMY was 86%, while B73 was only 8.25%, indicating that BMY, due to its better developed adventitious roots and the formation of aerenchyma induced under waterlogging stress, had a higher tolerance to waterlogging than B73 (P=2.45E-08). At the physiological and biochemical level, MDA (malondialdehyde) content in B73 increased significantly after 6 days of waterlogging, while it remained at a relatively low level in BMY. Moreover, POD (peroxidase) and SOD (superoxide dismutase) contents of BMY rapidly accumulated after waterlogging stress, in contrast to its relatively low level in B73, which proved that BMY had a strong scavenging ability of reactive oxygen species. The strong phosphorus absorption capacity of BMY enhanced its ability to resist abiotic stress. This study revealed the morphological and physiological basis of waterlogging tolerance at the seedling stage of the local germplasm BMY, and provided a theoretical basis for further use of this germplasm for breeding of waterlogging tolerant varieties.

Abstract:With the vigorous development of China's waxy maize industry, more and more waxy maize varieties have been approved. In this study, 308 approved waxy maize hybrids were used as materials to analyze by SSR markers the genetic diversity and genetic relationship of waxy maize hybrids from the aspects of year and suitable planting area. The results showed that a total of 529 alleles or 1480 genotypes were detected on 40 SSR markers in the 308 waxy maize varieties, and the PIC range was 0.226-0.890, with an average of 0.684. From the perspective of approval time, the genetic diversity index of approved varieties fluctuated little from year to year, and the highest genetic diversity of approved varieties in 2015 (0.720). From the perspective of suitable planting area, the PIC index of varieties in Xinan area was the highest, and the genetic distance between the varieties in Xinan area and those in other planting areas was the farthest, with an average of 0.0217. The results of cluster analysis showed that some varieties in Xinan area were clustered into a group, presenting certain regional characteristics. Among these cluster groups, Group III represented by ‘Jing Kenuo 2000’ had the largest number of varieties, and was distributed independently in the main coordinate map, which showed that the emergence of excellent varieties and the promotion of hetero-excellent model could enrich and broaden the genetic diversity of varieties, which would provide guidance for the improvement of new waxy maize varieties, and promote the development of waxy maize industry.

Abstract:Erect leaves are one of the important indexes for improving plant architecture and breeding dense-planting cultivars. In this study, an erect leaf (designated el, tentatively) mutant was identified by ethyl methyl sulfonate (EMS) induced mutagenesis in sorghum BTX623. The leaves of the mutant were erect from the six-leaf stage to the whole growth stage. At heading stage, the leaf length and width of the first leaf to the seventh leaf in mutant was significantly decreased. The leaf angle was larger at the lower leaves but became smaller at the upper leaves; the lamina joint length (except that the last leaf pillow is not formed) and auricle perimeter of each node showed the opposite trend. At the maturity stage, significant difference on spike length, grain number per panicle and growth period were observed while no significant difference on plant height, grain length, grain width, seed setting rate and 1000-grain weight was detected. Genetic analysis revealed a 3:1 separation ratio of the wild and mutant phenotype in F2 isolated population, implying that erect leaf was controlled by single recessive gene. Paraffin section analysis showed that this phenotype was caused by the increased number of lobar ear cells and lobar small vascular bundles. The results gained from this experiment laid a foundation for future gene cloning, and also provided gene resources and theoretical support for the analysis of the mechanism of sorghum leaf erect change and the breeding of dense planting cultivars.

Abstract:Adlay (or Job’s tears) is a cereal crop used for food and Chinese herb, and it is a necessary supplement in dietary structure diversity. In order to select germplasm resources in breeding procedure and production application, this study analyzed the endosperm type in adlay. It was shown by field tests that all germplasm accessions represented rich genetic diversity in the main agronomical traits. Endosperm type was identified and elite lines were selected from 116 adlay germplasms by rapid iodine reagent dyeing and Waxy genotyping methods. Twenty-nine wild germplasms were nonglutinous (none-waxy), and the waxy grain ratio was 0～25.00%. However, both types, either waxy or none-waxy, were found in 87 cultivated accessions including 8 nonglutinous varieties and 17 waxy varieties. Two types were simultaneously detected in 62 cultivar germplasms. Sixteen elite lines including 14 waxy and 2 nonglutinous were identified based on the agronomical performance and endosperm types. In waxy lines total starch and amylose contents were 57.82%～71.51% and 0～4.98%, respectively, while in two nonglutinous lines the total starch content was 65.73% and 65.65%, and amylose content was 23.75% and 25.48%. PCR amplification in waxy lines produced a 550 bp fragment, while in nonglutinous lines a ca. 850-bp fragment was detected. The contents of amylose and amylopection were differed obviously, and Waxy genotype were homozygous and stable in heredity, which could be used as fundamental genetic stocks in quality modification and genetic improvement in adlay.

Abstract:Dasypyrum villosum (2n = 14, VV) is an important tertiary gene pool of bread wheat. Excellent genes including powdery mildew resistance gene Pm55, stripe rust resistance gene Yr5v, and grain hardness gene Dina/Dinb were located on chromosome arm 5VS of D. villosum. The newly developed Triticum aestivum - Dasypyrum villosum T5VS.5AL and T5VS.5DL translocation lines provided germplasms for bread wheat improvement in disease resistance and end-use quality. In order to make efficient use of the translocation lines in wheat breeding programmes and analyze the genetic effects of the 5VS chromosome arm in wheat background, sequence information of T5VS.5DL translocated chromosome was isolated by the combination of chromosome sorting and next-generation sequencing. A total of 69 COS markers were developed by comparing the 5VS sequence information with genes on wheat ‘Chinese Spring’ homologous chromosome arms 5AS, 5BS and 5DS. After PCR amplification, 59 COS markers were identified with D. villosum 5VS specific bands, and the polymorphism rate was 85.5%, of which 40 markers were co-dominant between 5VS and homoeologous chromosome arms 5DS/5AS of wheat, and 19 markers were dominant. These markers provided information for physical mapping of beneficial genes on 5VS, and would contribute to development of small segment of 5VS in wheat. The T5VS.5AL and T5VS.5DL translocated chromosomes were introgressed into the genetic background of ‘NAU0686’ through backcross for 6 times. Comparing of powdery mildew reaction and molecular marker identification in BC6F2 generation, the reliabilities between co-dominant markers with simple amplified bands and 5VS chromosome arm were verified. In BC6F2:3 near-isoline population, the genetic effects of 5VS chromosome arm in ‘NAU0686’ background were further clarified. The results indicated that T5VS.5AL and T5VS.5DL translocated chromosomes could reduce grain hardness, plant height and 1000-grain weight, and increase grain number per main spike. The newly developed 5VS-specific molecular markers and the new germplasms laid a foundation for the efficient use of the two-translocation lines to breed new weak gluten wheat varieties with high quality and disease resistance.

Abstract:To explore the fertility restorer genes of C-type cytoplasmic male sterility (CMS-C) in maize, and analyze the gene functions, two F2 mapping populations were developed with restorer line K932R and two CMS-C allogeneic heterogeneous sterile lines K169S and K932S, respectively. Combined with SSR molecular markers and BSA-reseq technology, the fertility restorer gene in K932R was mapped. The target gene was cloned by PCR technology and gene expression analysis was performed. The results showed that the fertility restorer gene Rf 932 was mapped on the short arm of chromosome 8 by BSA-SSR molecular markers, between SSR markers 8-21 and 8-30, with the genetic distance of 2.3 cM and 7.7 cM, respectively. Rf 932 was located in a 0.38 Mb region on chromosome 8 by BSA-reseq technology, which contained 7 candidate genes. After the candidate genes being cloned in segments and aligned in sequences, Rf 932 was obtained with a full length of 2549 bp, consisting of 4 exons and 3 introns, encoding 385 amino acids; one of the key sites controlling fertility restoration, F187Y, had the same amino acid variation as Rf4, which was a new Rf4 allele; Rf 932 encoded a bHLH transcription factor that regulated the tapetum development. qRT-PCR analysis showed that there was no significant difference in the relative expression levels of Rf 932 in anthers between the sterile line and the restorer line at 3 developmental stages. The results enriched the restore gene bank of maize CMS-C, and laid a foundation for further analyzing the mechanism of fertility restoration.

Abstract:This study analyzed the genetic resistance gene against P. xanthii race 1B in BC1 and F2 populations which were derived from a cross of resistant parent MR1 and susceptible parent Xinmi1 in melon. By taking use of the bulked segregation analysis (BSA) using molecular markers, the polymorphisms between both pools (R vs S) were revealed followed by preliminary mapping and marker saturation in fine mapping. The segregation analysis revealed a single dominant resistance gene Pm-M against powdery mildew on chromosome LG12, flanked by SSR12212 and InDel 2276. The physical interval containing Pm-M was delimited to 75.5-kb (Chr 12:22765111-22840651), where 16 genes were annotated. Among them, 12 genes were considered to be candidates underlying the powdery mildew resistance. Collectively, this study laid a foundation for map-based cloning of the disease resistance gene Pm-M and its use in breeding for disease resistance melon varieties.

Abstract:Peanuts are an important product as part of the world's cereals, oils and foods. The testa colors of peanuts are white, red, purple, pink, and variegated. Variegated peanut testa are unique and can be distinguished from other types. In this study, the variegated testa peanut VG-02 was adopted as the research material. The study showed that the differentially expressed miRNA-enriched metabolic pathways related to the color synthesis included phenylpropane biosynthesis, flavonoid biosynthesis, isoflavone biosynthesis and rhythm-plant. MiRNA sequencing results showed that 86 miRNAs were differentially expressed of which 20 miRNAs were related to the color synthesis in variegated testa peanut. Twenty differentially expressed miRNAs related to anthocyanin synthesis in variegated testa peanut including miR_8, miR_50, miR_51 and miR_239-x, that jointly targeted anthocyanins, anthocyanidins and IFS target gene. Five miRNAs were found to targete structural genes in the anthocyanin biosynthesis: miR_398-x which regulates CHS target genes, miR_482 which regulates 4CL target genes, miR_266 and miR_182 which regulate F3'H target genes and miR_5 which regulates the anthocyanin 3-O-glucoside target gene. MiR858-y is a miRNA targeting anthocyanin biosynthesis regulation gene, which targets and regulats MYB2 and MYB3. MiR_10, miR_15, miR_61, miR_72, miR_102, miR_116, miR_123, miR_193, miR_256 and miR_862-z target CYP450 target genes.The joined analysis of KEGG metabolic pathways by miRNA sequencing and transcriptome analysis indicated that flavonoid biosynthesis is the most direct metabolic pathway for the synthesis of testa variegation. This study further our understanding of the molecular mechanisms of anthocyanin synthesis in variegated testa peanut.

Abstract:Anthocyanins are plant secondary metabolites with important physiological activities, and deciphering the mechanism of pigment formation has become one of the most important research hotspots. In this study, the peanut varieties including Zizhenzhu (purple testa), Hongzhenzhu (red testa), G110 (pink testa) and Baizhenzhu (white testa) were analyzed using RNA-Seq and liquid chromatography tandem mass spectrometry (LC-MS/MS), by using testa samples harvested at 30 and 45 days after flowering (30 DAF and 45 DAF), respectively. RNA-Seq revealed 32805 differentially expressed genes (DEGs), which were enriched in different number of pathways using KEGG analysis. GO analysis revealed 34, 21 and 19 DEGs which were enriched to the pathways of oxidation-reduction process, anthocyanin-containing compound biosynthetic process and Flavonoid biosynthetic process, respectively. LC-MS/MS analysis showed types of metabolites including proanthocyanidins, petunidin, paeoniflorin, malvadin, delphinium, cyanidin and their derivatives. Procyanidins A1, A2, B2, B3, delphinium and cyanidin were significantly up-regulated in each comparison group, with a variation of 5.82-19.52 on fold. Two pathways consisting of anthocyanin biosynthesis and flavonoid biosynthesis were enriched. The transcriptomic-metabolomics combined analysis showed that flavonoid biosynthesis is the key synthesis pathway for testa color formation, and delphinidin and cyanidin are the main differential metabolites. Out of 20 important genes, each), qRT-PCR analysis showed that PAL, 4CL, IF7MAT, CHI, F3H, DFR, LAR and LDOX were significantly up-regulated; C-CoA and FLS were observably down-regulated at 30 DAF; PAL, HCT-1 and DFR were significantly up-regulated; CHS, C-CoA and FLS were observably down-regulated at 45 DAF. Collectively, these results laid a theoretical foundation for future deciphering the molecular mechanism of peanut testa anthocyanin synthesis, valuable in breeding for peanut varieties with enriched anthocyanin.

Abstract:In this study, cassava ‘Xinxuan 048’ was used as the material to observe and determine the morphological structure, endogenous hormones and the contents of carbon and nitrogen compounds in different stages of flower differentiation, and to conduct exogenous hormone regulation research to reveal the rules and the physiological mechanism of cassava flower differentiation. Cassava plants complete the whole process from flower bud differentiation to the end of flowering in 30 d, producing mainly two types of inflorescences: staminate and oligopistillate-monoecious. Both pistillate and staminate primordia were present in the same flower bud before sexual differentiation. The stamens gradually degraded in the female flowers 5 to 8 d after elongation of the inflorescence, while pistils gradually degraded and disappeared 5 to 7 d after elongation of the inflorescence, resulting in unisexual flowers. The contents of CTK and ETH were higher in female flowers than in male flowers in all the stages of differentiation; the GA3 content was higher in male flowers than in female flowers in the initial and middle stages of differentiation; the IAA content was significantly higher in male flowers than in female flowers in the middle stage of differentiation; the ABA content in male and female flowers was not of much difference in all the stages of differentiation; the contents of carbon and nitrogen were higher in male flower buds than in female flower buds, and the ratio of C/N was also higher in male flower buds than in female flower buds, especially in the initial stage of differentiation (5 d). The results of the study on the regulation of differentiation of male and female flowers by exogenous hormones showed that different concentrations of 6-BA and ETH had different promoting effects on females. The concentration of 6-BA and ETH at 60 mg/L and 1920 mg/L were the best, while GA3 promoted the formation of male flowers, with the optimal concentration being 40 mg/L. It can be concluded that the key period for female flower differentiation of cassava is 5 to 8 d after inflorescence elongation, and the key period for male flower differentiation is 5 to 7 d after inflorescence elongation. CKT and ETH can promote the female flower differentiation of cassava, and GA3, IAA and higher C/N ratio are more conducive to the male flower differentiation of cassava.

Abstract:FPF1 (flowering-promoting factor 1) is one of the important family involved in the genetic control of flowering time in plant. So far, the knowledge concerning the FPF1 family in Aechmea fasciata has been very much limited. In this study, the AfFPF1 gene was cloned from A. fasciata, a tropical flower, based on the transcriptome sequencing data. The protein encoded by this gene contained 103 amino acids and had a molecular mass of 12.06 kD. The AfFPF1 gene was ectopically expressed in Arabidopsis thaliana, which advanced the flowering time of A. thaliana, reduced the number of rosette leaves and promoted the growth of root system. Some flowering-promoting genes such as AtFT, AtAP1, AtLFY and AtSOC1 were found to be significantly increased in the transgenic plants, while the expression of the flowering-inhibiting gene AtFLC was down-regulated. This further confirmed that AfFPF1 could positively regulate the flowering time in A. thaliana and might interact with these genes. These results demonstrated that AfFPF1 might be involved in regulating the flowering process of Aechmea fasciata, providing a theoretical basis of characterization of AfFPF1, the regulation of A. fasciata flowering using genetic approach and the molecular mechanism of ethylene-induced flowering in the near future.

Abstract:Chitinase (CHi) is a disease-related protein that can catalyze the hydrolysis of chitin in fungal cell walls and plays an important role in the interaction between plants and fungi. In this study, using the protein sequence of the Arabidopsis chitinase gene as the query sequence, BLASTp alignment was performed in banana A genome (DH-Pahang), and 23 MaCHis gene family members were identified. According to their position on the chromosome, they are named MaCHi01 up to MaCHi23, respectively. Phylogenetic tree analysis showed that the 23 MaCHis can be divided into two subfamilies, GH18 (glycosyl hydrolase 18) and GH19 (glycosyl hydrolase 19). Transcriptome data analysis showed that MaCHi05, MaCHi06, MaCHi07, MaCHi11, MaCHi18, MaCHi19 and MaCHi20 genes were significantly down-regulated or not expressed in the susceptible variety ‘Baxijiao’ after inoculation with Foc TR4, and significantly up-regulated in the disease-resistant variety ‘GCTCV-119’. Using RT-qPCR technology to analyze the expression of MaCHi05, MaCHi06, MaCHi07, MaCHi11 and MaCHi19 in the resistant and susceptible varieties inoculated with Foc TR4, it was found that the expression of these genes was activated in the resistant variety, but not in the susceptible variety, and the relative expression in the resistant variety was much greater than that in the susceptible variety, indicating that these genes participated in the process of banana fusarium wilt resistance in a positively regulated manner. The results of this study provides a theoretical reference for further analysis of the functions of the members of the MaCHi gene family in the process of banana fusarium wilt resistance.

Abstract:Pre-harvest sprouting (PHS) is one of the most serious problems in indica rice production. Generating new germplasm with elevated PHS resistance is applicable by editing dormancy-related gene. Taifeng B (TB) is a maintainer line of indica hybrid rice showing high eating quality, whereas this line shows higher PHS. Two genes MPK7 and MPK14 negatively regulates seed dormancy in japonica rice, but whether both result in elevated PHS resistance in indica rice remains unclear. In this study, in order to generate the germplasms with PHS resistance, we deployed CRISPR/Cas9 technology to edit MPK7 and MPK14 in TB via Agrobacterium-guided transformation. Six lines harboring modified target sequences were screened from the transgenic offspring by sequencing, and two were selected for analyzing the seed dormancy. The results showed that the homozygous mutant significantly delayed the seed germination, rather than heterozygous mutants which also exhibited improved PHS resistance if compared to the wild type TB. No significant difference in plant height, number of tillers and grains per spike between the homozygous mutant and TB was observed. As a result, this study generated PHS resistant lines by CRISPR/Cas9 strategy, which provided theoretical technology and material support for the PHS resistance research and rice breeding.

Abstract:SNP genotyping chip is an important tool for molecular breeding. High density SNP chip often has some problems such as marker redundancy, high price, and poor target, limiting its use in the normalization and scale of molecular breeding. Here we developed a low density breeding chip. The panel of 6,056 markers were assembled using three resources, consisting of: (1) 2,080 key SNPs of 18.2Mb SNPs which were identified from 10X sequencing of 37 maize inbred lines; (2) 3,390 qualified markers with low missing rate, high polymorphism and Conversion Type being as Poly High Resolution within 55K SNP array; (3) 586 markers that were selected from HapMap3. Genotyping by target sequencing (GBTS) technology was used to detect the markers. Through the verification of natural population, bi-parent population and multiparent advanced generation inter-cross (MAGIC) population, the average capture rate of the breeding chip was 70.6%. The original design markers were detected ranged from 4,773-5,963, and 57.6% and 88.6% markers were found by applying minor allele frequency (MAF) > 0.4 and polymorphic information content (PIC) > 0.4, respectively. We evaluated 226 inbred lines with this breeding chip. Within this collection two groups (temperate vs. tropical) had been classified by principal component analysis (PCA), and six known groups (Reid, Lancaster, PB, LRC, SPT and tropical) were proposed using cluster analysis. Structure analysis has not revealed the best K value. The mean genetic distance within and among groups were 0.394 and 0.472, respectively. The genetic distance within PB group was the smallest (0.316), and the genetic distance within tropical group was the largest (0.424). The largest genetic distance (0.493) was observed between group Reid and tropical. The genetic differentiation coefficient (FST) among the groups indicated that the FST of PB group was larger than that of other groups.