Abstract:Maize key inbred line Huangzaosi had been developed in the 1970s in China， exhibiting merits including robust adaptability， high combining ability， compact plant shape， short growth period and fast grain filling. To date， hundreds of maize inbred lines with the genetic components derived from Huangzaosi have formed a core maize germplasm group referring‘ Huanggai’ group（ or Tangsipingtou Group） . The hybrids developed by Huangzaosi and its derived lines have been popularized and cultivated up to hundreds of millions hectares， including the current leading varieties in China， Jingke968 and Zhengdan958. Although this line has played an important role in the maize breeding history in China， its pedigree and origin still remain unclear. Here， according to previous description of the breeding processes of Huangzaosi， we inferred that the white kernel inbred line of Tangsipigtou was initially out-crossed with another maize breeding material with earlier maturation and yellow-colored kernel followed by the backcrossing in the Tangsipingtou field， from which Huangzaosi was finally developed through later artificial selfing and selection. The comparison of DNA molecular fingerprints obtained by the 40 core SSR markers for Huangzaosi， Tangsipingtou and 9 landraces and inbred lines planted in the early 1970′ s indicated that Huangzaosi and Tangsipingtou shared the same 28 SSR loci， and the rest 12 were only identical between Huangsipingtou and Huangzaosi. Whole genome-based IBD genetic structure analysis further demonstrated that Tangshipingtou was the major donor for Huangzaosi， and Huangsipingtou was another parent. In addition， the correspondence comparison of phenotypic and morphological traits confirmed that the phenotypic and agronomic characteristics of Huangzaosi were consistent with the conclusion that it was derived from the crossing of Tangsipingtou and Huangsipingtou. To sum up， this study deciphered the long mystery of the origin of‘ Huangzaosi’ .

Abstract:The reference genome provides a fundamental framework in the field of modern functional genomics. Modern genomic techniques based on reference genomes is the driving force for identification of genetic variations and functional gene cloning in the past two decades. However， with the progress of plant genome research， it is becoming visible that single reference genome cannot represent all the genomic variances within a species or a population. This consequence has become one of the limits for the functional genomic studies. Pangenome refers to the full complement of genes/genomic sequences within a population. By capturing and presenting all the genes/genomic sequences within a population， pangenome can be used as reference genome in functional genetic studies， to overcome the limit posed by single reference genome. While implementing in the state-of-art genomic techniques， pangenome can greatly improve the efficiency and precision of identification of genetic variations in plant germplasm， thus becoming one of the frontiers and hotspots in genomic research. In this review， we summarized the definition and recent progress in studies of pangenome， the techniques and strategies applied in pangenome assembly and construction， as well as the application of pangenome in plant genomic and molecular breeding. The current problems and future perspectives of plant pangenome were outlined. This review is expected to provide a better understanding and reference for future study and application of plant pangenome.

Abstract:Radiation mutagenesis breeding has been widely used in crop genetics and breeding due to its short duration needed， high mutation rate and stable offspring traits. In the past 10 years， 18 varieties that play a vital role in rice production had been raised by using radiation mutagenesis indicating that the radiation mutagenesis could provide new germplasm resources for rice breeding. In this paper， rice mutants obtained by radiation mutagenesis， including stem mutants such as high stem， short stem， thick stem， twist stem， etc.； leaf mutants such as leaf color， leaf length， striped leaf， spotted leaf， etc.； panicle mutants such as panicle length， panicle color， grain size， etc.； mutants related to physiological traits such as premature senility， sterility， late maturity， without heading， etc. were reviewed. Also， the mapping， cloning and action mechanism of yield related mutants， stem related mutants， leaf shape related mutants， panicle related mutants， resistance related mutants and rice quality mutants were systematically introduced. In addition， seeds of the rice cultivar Zhejing 99 were mutated by radiation mutagenesis， and we obtained many types of mutants. The phenotypic analysis of these mutants laid a foundation for the cloning of rice genes and provided novel germplasm resources for rice breeding.

Abstract:Great achievements have been made in crop germplasm resources conservation and utilization in China， but there are also problems such as unclear background， low efficiency of sharing， unclear ownership of germplasm resources， etc.， which can be effectively solved by carrying out crop germplasm resources registration. From the perspective of crop germplasm registration information flow， this paper analyzed the overall workflow of crop germplasm resources registration and designed the crop germplasm resource registration blockchain model. Firstly， according to the business characteristics of crop germplasm resources registration， determined the users and main process of registration， which includes three stages： data filling， review and sharing. Then the blockchain network model， workflow model and data model was designed. Finally， improved the DPOS consensus mechanism， according to the business demands of crop germplasm resources， and the construction method of incentive mechanism was given. The blockchain model of crop germplasm resource registration realizes the distributed storage of registration data through decentralization， increases the reliability of data through DPOS consensus mechanism， ensures that the data in the chain is difficult to tamper with and easy to trace through the special data structure of blockchain， which improves the data security. This paper provides a new idea for the development of crop germplasm resources registration system in the future.

Abstract:Zhoumai 22 is not only the major cultivar in China, but also has become an important breeding parent in Huang-huai river valley winter wheat region. In order to reveal the genetic diversity and contributions of Zhoumai 22 to its derivatives and provide a reference for parent selection, we analyzed 106 derived varieties (lines) of Zhoumai 22 by genealogy and selected its earlier derived 80 varieties (lines) for SNP genotyping using the Affymetrix 55K SNP chip. The results showed that the 106 derivative lines of Zhoumai 22 involved 82 direct parents, and the main ones used as the opponent parents were Bainong AK58、Zhoumai 24, Zhoumai 18, Luomai 21, Zhoumai 16, Zhoumai 19, etc. These parents were directly or indirectly derived from Zhou 8425B and Zhoumai 9 and belonged to the "Zhoumai" consanguinity family. Of the A、B、D genomes, the B genome has the largest number of polymorphic loci, the D genome has the least number of polymorphic loci, but the ratio of polymorphism SNP to raw SNP number of A and D genomes is basically the same. Genetic similarity between Zhoumai 22 and 80 derived varieties (lines) ranged 0.392~0.856 with an average of 0.685, while genetic similarity among the derived lines varied from 0.381 to 0.991 with an average of 0.676. There were some genetic diversity differences among Zhoumai 22 and its derivatives. The 81 varieties were divided into 8 subpopulations, of which the I、II、III and IV subpopulations had richer genetic diversity and the V、VI、VII and VIII subpopulations was insufficient on genetic diversity. Through the polymerization of high quality protein subunits and differential selection, the new wheat varieties with high yield and multi-resistance and high quality characteristics were bred, such as Zhoumai 26, Cunmai 8, Zhoumai 36, Cunmai 11 and so on.

Abstract:Lodging is one of the main factors affecting the yield of common wheat（ Triticum aestivum L.） . Improvement of lodging resistance in varieties is a key goal in wheat breeding. In this study， 528 wheat varieties and lines from China were used to determine the phenotypic characteristics that affect lodging. Statistical analysis including genetic variation analysis， correlation analysis， principal component analysis， multiple linear regression analysis and cluster analysis were used to evaluate the lodging resistance. A wide range of genetic variation was observed at six characteristics reflecting lodging resistance. The basal internode length and plant height were negatively correlated with resistance to the thrust， while the basal internode diameter was positively correlated with the resistance to thrust， however， no significant correlation between the basal internode length and the internode diameter was observed. Principal component analysis showed that information about all characteristics could be represented by three principal components， with the cumulative contribution rate of 83.837%. Regression analysis revealed that the first internode diameter， first internode length， second internode diameter， second internode length， and plant height significantly affected the thrust of wheat. Cluster analysis based on the thrust suggested four groups from the tested genotypes， among which 66 wheat varieties（ lines） in the first group represented the strongest lodging resistance. Collectively， these results provided a theoretical basis for the use of lodging-resistant varieties in agriculture， and also the evaluation method of lodging resistance in parents and derived offsprings.

Abstract:In order to understand the genetic basis of salt tolerance in wheat， the SNP loci and candidate genes which were significantly associated with salt tolerance were explored. Three hundreds of wheat varieties （ lines） were subjected for tests of salt tolerance using 200 mmol/L NaCl and normal nutrient solution， respectively， and these varieties were genotyped with 90 K chips exploring 16650 polymorphic SNPs. The statistical analysis was performed by using the Q+K association mixing model for eight root traits including the longest root length， root dry weight， root fresh weight， average root diameter， root tip number， root surface area， root volume and total root length. The results showed that the root traits showed extensive phenotypic variation， with a coefficient of variation of 24.3% to 50.0%， and a polymorphic information content（ PIC） of 0.170-0.562， as well as a genome-wide LD attenuation distance of 6 Mb. Three subgroups were suggested by population structure analysis， including： Subgroup I， which included 143 genotypes（ 47.67%） mainly from Henan， Shaanxi， and Sichuan provinces； Subgroup II， which included 74 genotypes（ 24.67%） mainly from Beijing； Subgroup III， which is represented by 83 lines（ 27.67%） mainly from Henan. Seventy-seven SNP loci（ P ≤ 0.001） were detected by genome-wide association study to be significantly associated with salt tolerance traits， and they were distributed on 20 chromosomes except chromosome 6D in wheat. Each of SNPs contributed to 3.70% to 19.45% of phenotypic variation， in which 6 loci such as RAC875_c13169_459 on chromosomes 1A， 3A， 4A， 7A， 3D， and 5D are simultaneously associated with two or more traits， with a contribution rate of 3.78%-19.45%. Based on the physical positions of 77 SNP loci， 17 candidate genes associating with wheat salt tolerance have been proposed. For example， TraesCS5B01G031800（ Cation/H （ +） antiporter） might play an important role in the transport of cations such as Na+； TraesCS5A01G329000 （ Defensin） might play a role in blocking the entry of cations such as Na+. TraesCS2A01G079000（ Repetitive proline-rich cell wall protein） might function in the formation of cell walls. Collectively， these candidate genes which have been identified from this study are proposed as important genes for salt tolerance in wheat.

Abstract:Drought is one of the major limiting factors that affect the wheat yield production in north China. Identification of drought-resistant accessions from newly released wheat varieties is of great importance， in order to ensure stability of wheat production in this area. The present study attempted to screen droughtresistant varieties from 13 wheat varieties in central and north area of Hebei province under field conditions with different water regimes. If compared to normal watering regime， several agronomical traits including plant height， thousand kernel weight， kernels per spike， spikes per mu， grain yield， chlorophyll content and leaf water loss rate in vitro of wheat decreased significantly with variation under limited water regimes. A slight difference on the resistance level of the varieties was observed using three indexes consisting of drought resistance index （ DI）， weighed drought resistance index（ WDI） and drought-resistance comprehensive evaluation value（ D） respectively， while two varieties were qualified showing drought-resistant. Three water-saving varieties have been identified by evaluating with water-saving index. Among the agronomic and physiological traits tested， the chlorophyll content， spikelet per spike， plant height， water loss rate of cutting leaves， flag leaf length and kernels per spike were found to be associated with drought resistance， and the chlorophyll content and spikelet per spike might serve as indicators simplifying the drought evaluation process.

Abstract:The high temperature at the grain filling stage of spring wheat is harmful to the yield production and exploration of the quantitative loci with elevated high-temperature tolerance becomes of interest in wheat breeding. In this study, a recombinant inbred line population derived from the cross of two spring wheat lines ‘Avocet’ and ‘Sujata’ was used for the quantitative mapping of the genetic loci that associated with TKW (thousand kernel weight), KL (Kernel length) and KW (Kernel width) as well as analyzing the interaction pattern of QTLs responding to high temperature at the grain-filling stage. The field trails were conducted at four environments (Gaocheng, Shijiazhuang, 2016-2018; Tianjin, 2017). Twenty quantitative loci were detected at all of four environments, including five QTLs associated with KL, four with KW and eleven with TKW. Four loci QTkw-5A.1/QKl-5A, QTkw-2A.1/QKw-2A.2, QTkw-3B.2/QKw-3B and QTkw-6A/QKw-6A were found with double functions. Three TKW-QTLs (QTkw-2A.1, QTkw-4B and QTkw-5A.1) were detected specifically at different environments. Seven TKW-QTLs were detected at Shijiazhuang, where highand/ or super-high temperature was observed in two calendar years of 2017 and 2018. Two major QTLs (Tkw-2A.1 and QTkw-5A.1) explained 13.8% and 17.3% of phenotypic variation, respectively, whereas five minor QTLs (QTkw-2A.2, QTkw-3B.1, QTkw-3B.2, QTkw-4A.2 and QTkw-6A) contributed to 7.4%-9.9% of phenotypic variation. Out of nine TKW-QTLs detected in Shijiazhuang, six and three represented additive effects from Sujata and Avocet, respectively. Thus, the parental line ‘Sujata’ represented more elite alleles causing higher TKW and wider adaptability.

Abstract:High temperature at reproductive stage destabilizes grain yield and quality especially in warm climate wheat production region. Breeding for heat-tolerant wheat varieties is an important target of wheat breeding in China， while identification of the molecular markers associated with the heat tolerant traits can accelerate this process. The heat-tolerant indexes of five kernel traits including thousand kernel weight， kernel length and kernel width， kernel surface area and kernel circumference were investigated by taking use of 169 wheat varieties（ lines）， and genotyping with SSR marker Xwmc44 identified three allelic variants I， II and III. A significant positive correlation between variant I and heat-tolerant indexes of four kernel traits（ thousand kernel weight， kernel width， kernel surface area and kernel circumference） was observed. The average values of heat-tolerant indexes of kernel traits in wheat varieties（ lines） with I allelic variation was greater than 1. The wheat varieties with variant II was negatively correlated with the heat tolerance index of thousand kernel weight （ P<0.01）， and negatively correlated with the heat-tolerance index of two kernel traits including kernel width and kernel circumference（ P<0.05） . The average value of heat-tolerance indexes of kernel traits in wheat varieties （ lines） with II allelic variation was less than 1. No detectable association was observed in variant III with the heat-tolerance indexes. These results showed that Xwmc44 was related to heat tolerance of wheat， and II allelic variation was a superior allele for heat tolerance of wheat. This will provide more information for heat-tolerant wheat breeding with molecular markers.

Abstract:Awn is a needle-like structure located on the ear of plants. It is widely found in the grass family such as rice， wheat， sorghum and barley， and the structure of awn varies in different crops. In wheat， awn plays an important role in improving the photosynthetic efficiency and yield， and in preventing damages caused by pest birds， insects and adverse conditions. Genes related to the development of wheat awn have already been mapped and genetically analyzed， but only one of the four major awn-inhibiting genes， B1（ Tipped1）， has been cloned. In this study， conducted on a BC3F6 genetic population（ YN3/YZ1） and a natural population， we estimated the relationship between the awn and agronomic traits， and found that awn had significant effects on plant height and yield. Genome-wide association studies（ GWAS） based on wheat 660K SNP array identified genomic regions on chromosomes 5AL and 6BL significantly related to awn trait， which corresponded to awn-inhibiting genes B1 and B2 respectively. From transcriptome data of long-awned and tip-awned near-isogenic lines（ NILs）， 23 differentially expressed genes were identified from the 6BL candidate interval. These results will facilitate the B2 gene cloning in the future.

Abstract:The components， which are derived from the lipid metabolism of barley malt， destabilizes the beer flavor and its shelf life in the brewing industry. The lipoxygenase 1（ LOX-1） has been approved as the key enzyme involved in lipid metabolism in barley seeds. The identification and development of null LOX-1 barley germplasm might be of interest to promote high-quality malting barley breeding. By taking use of the previously-identified null LOX-1 Chinese barley rare allelic variation， here a Kompetitive Allele Specific PCR（ KASP） based diagnostic marker was generated and subjected for a test in 633 barley landraces which originated from Shandong and Henan province. A total of eight null LOX-1 barley accessions were identified， the geographic distribution and the allele frequency were further investigated. Taken together， this work provided LOX-1 free germplasm accessions valuable for the malting barley breeding especially in conjugation with the newly-generated KASP diagnostic

Abstract:In order to make better use of Tibetan hulless barley, the content of 17 amino acids (except tryptophan) for 72 hulless barley accessions was determined, and the nutritional value and flavor of amino acids was evaluated by WHO/FAO/UNU model. The cluster analysis was performed using the amino acid composition, and the difference of nutrition between landraces and modern varieties was surveyed. The total content of amino acids in hulless barley was 87.454 mg/g DW, with a range from 47.8 to 178.7 mg/g DW. The indispensable amino acid accounted for 37.15%, which was higher than that of oat, hulled barley and wheat. The Tibetan hulless barley exhibited the highest content (23.27%) of glutamine with large variation (CV=33%), and the lowest methionine (1.75%). The composition of amino acids in Tibetan hulless barley was similar to that in hulled barley and wheat. The Tibetan hulless barley had higher content of lysine compared with other cereal crop grains. The close degree U of hulless barley was 0.903, and 69.44% of the tested accessions was more than 0.900. That indicated that the composition of indispensable amino acid of Tibetan hulless barley were close to the model protein and thus had higher nutritional value. The Tibetan hulless barley genotypes presented broad variation on the sum of dispensable amino acids (28.7-118 mg/g DW), with the average of 55.785 mg/g DW. The content of amino acid contributing freshness was 26.58 mg/g DW and that for sweetness was 21.85mg/g DW. For nutrient balance, hulless barley was higher among cereal crops, the value of Score of Ratio Coefficient was 73.14. The content of amino acids in landraces/historic varieties was higher than that of improved varieties. Notably, four accessions were identified with the qualified nutritional value and flavor amino acid content. Thus, by unlocking the content of amino acids in hulless barley accessions, this study provided valuable insights to select elite genotypes in breeding for high-quality food hulless barley varieties.

Abstract:With the change of the global climate， the drought tolerance at germination stage of soybean becomes of importance when suffering spring drought. In order to explore an optimal drought stress condition， four soybean accessions with levels of drought tolerance were tested with the concentrations of 0%， 10%， 15%， 16%， 18%， 20%， 30% of PEG-6000 solution simulated different drought conditions. The result showed that 15%~18% of PEG-6000 solution was qualified to simulate drought stress condition at germination stage of soybean. Moreover， 16% of PEG-6000 solution was applied to culture the seeds of 568 soybean germplasm accessions. The indexes were estimated using six indicators including relative germination energy， relative germination rate， relative radical length， relative bud length， germination drought tolerant index and vigor index. Based on subordination function method and the standard classification of drought tolerance in soybean， four drought tolerant varieties， 18 medium tolerant varieties， 110 intermediate type varieties， 194 relatively drought sensitive varieties and 242 drought sensitive varieties were identified.

Abstract:Soybean is an economically-important food crop that contains about 40% of grain protein. The soybeans harvested from China are mainly used for food， and breeding for higher protein content is one of the main targets in soybean. Exploration of the genes related to soybean protein content and development of molecular markers are thus of great significance. In this study， a recombinant inbred line population was used by crossing a low protein soybean variety‘ ZH35’ （ female parent） with the high protein accession‘ Tokachi nagaha’ （ male parent） that was introduced from Japan. With the Bulked Segregant Analysis（ BSA） analysis， nine SSR markers that associated to protein content were identified on three chromosomes， including chromosome 19 where no QTL was previously reported. This QTL qPRO-19-1 was allocated using an inclusive complete interval mapping method（ ICIM-ADD） to the genetic interval of the molecular markers SSR_19_38 and SSR_19_59. This elite allele， which was derived from‘ Tokachi Nagaha’ ， could explain 7.81% and 14.87% of phenotypic variations in F2： 15and F2： 16 with the LOD values of 3.43 and 3.98， respectively. The physical interval of qPRO-19-1 expanded 385 kb that harbored 36 annotated genes. Collectively， the genetic mapping of the new QTL qPRO-19-1 laid the foundation for map-based cloning gene and molecular marker assisted breeding for high protein soybean varieties.

Abstract:Gly m Bd 30K protein is recognized as a major immunodominant allergen in soybean， and this protein can lead to anaphylaxis such as diarrhea and intestinal inflammation in humans and livestock. The exploration of germplasms with lower Gly m Bd 30K content is important in breeding for elite functional soybean varieties. In this study， we generated the polyclonal antibody targeting to the 190-379aa peptides of the Gly m Bd 30K protein， followed by quantifying the Gly m Bd 30K protein using Western blot in 30 soybean accessions that were derived from Shanxi province. The genomic sequence of the Gly m Bd 30K gene and its transcriptional level was further conducted. As a result， two germplasms（ 134， ZDD02046， Daqingdou， ZDD02174） with lower Gly m Bd 30K protein content have been identified， the identification efficiency is 6.9%. Both accessions displayed 8 and 42 TA repeats respectively in the promoter of the Gly m Bd 30K gene if compared with that of Willams82. The transcription level in 134（ ZDD02046） was found to be significantly lower than that of Daqingdou（ ZDD02174） . It is speculated that TA polymorphism in the promoter may associate with the Gly m Bd 30K expression. Collectively， this study established a strategy on the quantification of Gly m Bd 30K protein content and identified two accessions with lower Gly m Bd 30K protein， which will provide technical and material supports in breeding for new soybean varieties with high-quality proteins.

Abstract:Stem is an important constituent part of the maize plant， which closely affects lodging and grain yield. A study of the trend of stem-related traits of inbred lines of maize grown in China in different decades from 1960 s to 1990 s would provide references for maize breeding for lodging resistance and high yield. In this study， maize stem-related traits， including stem height（ SH）， ear height（ EH）， stem node number（ SN）， ear node（ EN）， stem diameter（ SD）， stem moisture content（ MC）， stem soluble sugar content（ Brix）， and ear height coefficient （ EHc） and ear node coefficient（ ENc） derived from some of them were investigated in 65 representative maize inbred lines of the different decades. Using these stem-related phenotypic data， ANOVA， correlation analysis and the trends in the different decades were studied. The results showed that there were significant differences in the stem traits among the maize inbred lines， while no significant difference of maize stem-related traits existed among the different decades； SH， EH， SN， and EN were decreasing from decade to decade； the EH improved significantly in the time period； around the 1980 s， the selection criteria of maize stem thickness reversed from robust to slender stems， which might be resulted from the breeding goal of increasing yield through rational dense planting； in the 1990 s， MC decreased by 3%， which was significantly different from the 1980 s. Maize lodging resistance has always been an important research in China， with EH improvement coming to a significant effect，and SN and EN becoming important focuses in maize breeding of lodging resistance and high yield.

Abstract:Classifying heterotic groups of super-sweet corn inbred lines， selecting inbred lines of high combining ability and constructing new stronger heterotic groups could provide basis for breeding excellent sweet corns. 23 self-bred super-sweet corn inbred lines were used to make up 60（ 3× 20） hybrid combinations with NC Ⅱ design to classify heterotic groups by analyzing the combining ability of yield and 56K SNP markers. The results indicated that the average heterozygosity of 23 inbred lines was 2.59%， and the homozygosity was higher. Except for GX06 and GX10， GX14 and GX15， GX16 and GX17， the genetic similarity between the inbred lines was less than 90%， which could be used as different inbred lines in breeding. The positive effect value of GCA in yield of the tester line GX21 and the tested lines GX01， GX03 GX12， GX13， GX18 was higher and they were excellent inbred lines. The results of evolutionary tree， PCA and clustering diagram of SCA classified the 23 super-sweet corn inbred lines into GX21 group， GX22 group and GX23 group. GX22（ HJZ33） group was named the male parent group， including 5 inbred lines（ GX02， GX11， GX19， GX20 and the tester line GX22）， GX21 （ GTL273） and GX23（ YC26） groups were named the female parent groups， including 18 inbred lines（ GX01， GX03-GX10， GX12-GX18 and the tester lines GX21 and GX23） . The results of SNP markers agreed with SCA of yield basically and using SNP markers to classify heterotic groups could shorten the corn breeding cycle significantly.

Abstract:This study attempted to build up a core collection of 1285 sorghum germplasm accessions at Shanxi Gene Bank. These accessions were historically investigated for the phenotypic variations 18 agronomic traits， and these datasets were subjected for tests using the combinations on sampling methods， sampling proportion and clustering methods. A pipeline combining multiple cluster deviation sampling method， 15% sampling proportion， euclidean distance and complete method was used. By pairwise comparison of phenotypic datasets in core collection（ 192 accessions） to all samples， the mean difference percentage（ MD） was 0， the variance difference percentage（ VD） was 83.33%， the coincidence rate of range（ CR） was 97.45%， and the variable rate of coefficient of variation（ VR） was 119.63%. Furthermore， eight accessions with particular characters were incorporated. This core collection including 198 landraces has been proposed， followed by tests using t-test， extreme value， standard deviation， the t-test of Shannon-Weaver diversity index， as well as principal component. As a result， 198 sorghum landraces are representative on the diversity of sorghum landraces hosted by Shanxi Gene Bank， and this collection might be useful in practical uses for sorghum breeding.

Abstract:Neck-panicle is the only channel for assimilation substance that transports to the panicle. In this study， 122 chromosome segment substitution lines（ CSSL） derived from the cross between indica rice variety 93- 11 and japonica rice variety Nipponbare were used to investigate vascular bundle-related traits of neck-panicle and yield traits. The results showed significant correlation between vascular bundle-related traits of neck-panicle and yield traits. A total of 42 quantitative trait loci（ QTL） of vascular bundle-related traits and 45 QTL of yield traits were detected. Among them， 16 and 14 chromosomal regions with positive allelic effects were from Nippnbare and 93-11， respectively. Gained from the QTL mapping results of these two types of traits， six QTL clusters that regulate both vascular bundle-related and yield traits have been identified. Based on previous studies and the candidate gene analysis， two pleiotropic genes Ghd7 at the 9 Mb site of chromosome 7 and IPA1 at the 25 Mb site of chromosome 8 might be candidate， respectively. These results suggested a diversified genetic basis with partial common genetic mechanism for both rice vascular bundle-related traits and yield traits. Exploration of additional QTLs controlling“flow” and multiple genes regulating the interaction between“flow” and“sink” might provide theoretical and practical significance in rice breeding.

Abstract:This study identified a pale-green leaf（ pgl） mutant in F8 generation of clustered-spikelet rice crossed with Japonica rice Nipponbare. The pgl mutant with the pale-green leaf at all the growth stages， represented significant reduction on plant height， flag leaf width， number of seeds per main pancile and 1000-grain weight when compared with its wild type. The content of chlorophyll（ Chl） b in pgl mutant is 0.002 to 0.003 mg/g， significantly lower than that in its wild type. The net photosynthetic rate of pgl mutant was the same as that of wild type plant at both tillering and full-heading stages. The ultrastructure analysis showed that the number of grana lamella of thylakoids in the pgl mutant were less than those in the wild type plant. The genetic analysis of the pgl mutant revealed one single recessive nuclear gene underlying the pigment phenotype. By whole-genome SNP-chip analysis using two bulks derived from the pale-green leaf plants and wild type plants in F2 segregating population respectively， pgl was located in the physical interval of 22806614 to 23000408 bp on the long arm of chromosome 10， linked with one SNP marker R1022900951CA， where the gene chlorophyll a oxygenase（ CAO1， LOC_Os10g41780） responsible for the synthesis of pigment is found. The allelism test between pgl and three pale-green mutants（ W1， Y406 and Y45） proved an allelic nature between pgl and mutant W1. DNA sequence of CAO1 revealed one base pair deletion（ T in 2507） and a T to C substitution in 3136 in pgl mutant， which results in a R to W substitution in the 9th exon. Collectively， this study provides new pale-green leaf mutants， which might be valuable in rice breeding and in the analysis of photosynthetic efficiency.

Abstract:“Late spring coldness” negatively affects rice seedling establishment and leads to rice growth retardation， albinism and rotten in Chongqing and southwest China， which severely restricts the production of high-quality rice and the application of optimal cultivation technologies. To investigate the cold tolerance of the chilling-tolerant indica cultivar Yu17S and chilling-sensitive indica cultivar Y58S seedlings， different parameters including the contents of soluble sugar， trehalose， proline， MDA and H2O2， the activities of antioxidant enzyme（ SOD， POD and CAT）， and the relative expression of stress relative genes were deployed. If compared with Y58S with the dead seedlings rate of up to 96.7%， Yu17S represented 7.5% of the dead seedlings rate， suggesting a stronger cold tolerance at the seedling stage upon the low temperature stress. The contents of both H2O2 and MDA increased in both cultivars under the low temperature stress， whereas both values of Yu17S were lower than these of Y58S. In Yu17S， the CAT， SOD and APX activity， soluble sugar and trehalose content， as well as the transcripts of genes OsCATB， OsSOD， OsAPx8， OsTPS1， OsTPP1， OsMKK6， OsMAPK3 and OsICE1 have been observed to be significantly increased. No significant differences on the proline content and on the expression of OsP5CS that controls the proline biosynthesis in both cultivars were observed. It is possible that the H2O2 signal molecule and trehalose of Yu17S may respond to the low temperature stress at the seedling stage， thus resulting in an enhancement on cold resistance.

Abstract:In this study， five fiber quality indexes（ Fiber upper half mean length FUHML， Fiber strength FS， Micronaire value MV， Fiber elongation FE， Fiber uniformity FU） of 214 upland cotton materials were tested under seven environments， and Boxplot were drew by SPSS19.0， and the heritability， correlation and phenotypic effect values of the traits were calculated by using the phenotypic data analyzed by BLUP. 259 SSRs with high polymorphism and uniform distribution on 26 chromosomes were used to scan polymorphism in 214 cotton materials， the polymorphism information of primers were calculated by PowerMarker 3.25， and molecular marker data and phenotypic traits were analyzed by the method of GLM（ General Linear Model）（ Q） in TASSEL software， phenotypic effect values were used to identify excellent allelic variants and typical materials carrying elite alleles. The result showed that the same one fiber quality trait had a relatively stable change trend in two to three years in three regions. There were positive correlations among FUHML， FS and FU（ P<0.01）， and FUHML/FS and MV/FE were negatively correlated. A total of 309 alleles and 774 genotypes were detected. The average polymorphic information content（ PIC） per marker was 0.2688， and the average genetic diversity index was 0.2239. Two hundred and fourteen upland cotton materials were divided into two subgroups by analysis of population genetic structure. A total of 134 loci associated with fiber quality traits were detected（ P<0.01）， among them， thirty loci could be detected stably in three or more environments. Three loci（ NAU6177， DPL0886， NAU3607） were found to be significantly associated with FUHML/FS， MV and FE respectively in seven environments（ P<0.01）， the maximum explanation rate up to 11.14%， 5.74% and 13.99% respectively. Thirty-one loci related to more than two fiber traits simultaneously， including the loci near NAU6177 related to aforementioned five fiber quality indexes（ P<0.01） . Compared with reported results， seventeen QTLs in this study has been reported to be related to fiber quality，in which 10 QTLs associated with the same traits. Based on the results， seventy-two alleles related with fiber quality were identified by phenotypic effect analysis respectively. Specifically， the allelic variation loci with the maximum increasing effect of FUHML， FS， MV and FE were NAU5387b（ +0.95 mm）， NAU5387b（ +1.25 cN/tex）， NAU943a（ +0.40）， and COT002a（ +0.62） respectively， and the allelic variation loci with the maximum decreasing effect of FUHML， FS， MV and FE were NAU6177e（ -1.21 mm）， NAU6177d（ -1.43 cN/tex）， CIR286b（ -0.78）， and NAU5387b（ -0.40） separately. Furthermore， five typical materials carrying elite alleles were selected， which were Ji 228（ FUHML）， Xinluzao 25（ FUHML， FS）， Ji N71（ FS）， Xinluzhong 36（ MV） and Xuzhou 142（ FE） . In conclusion， stable molecular markers associated with fiber quality were revealed by association analysis， and elite alleles and typical materials carrying elite alleles were identified， which could provide a reference for molecular assisted selection of upland cotton about fiber quality.

Abstract:The male sterile lines of diploid Chinese cabbage have been widely investigated for theoretical studies and practical uses. In tetraploid Chinese cabbage， improvement of fertility and seed setting rate in selfbred lines was favorable， while study of the male sterile lines remained un-investigated. In this study， a sterile source（ CMS hou36gao） with new Brassica rapa L. cytoplasmic male sterile（ CMS） gene was selected from the diploid Chinese cabbage， and subjected for chromosome doubling using colchicine treatment. By multiple consecutive cycles with tetraploid inbred lines D571 and D574， in conjugation with cytogenetically identifying the number of chromosomes， two tetraploid lines CMS-D571 and CMS-D574 that showed cytoplasmic male sterile were produced. Both lines showed sterility rate up to 100% with high seed setting rate and genetic stability. This study raised an example by using the cytoplasmic male sterility in tetraploid Chinese cabbage breeding， and established an experimental pipeline to generate the cytoplasmic tetraploid male sterile lines. Collectively， this work laid a foundation for innovation and practical use of male sterile lines in tetraploid Chinese cabbage.

Abstract:In this study， interspecific hybridization between Brassica napus L.（ 2n=38， AACC） and Brassica rapa L.（ 2n=20， AA） was performed， followed by cytological and molecular analyses of the progenies at the early generations in order to achieve rapidly acquisition of novel B. napus L.. The results showed that the F1 plants obtained from the crosses between B. napus L. and B. rapa L. represented 29 chromosomes and low pollen fertility， with the phenotypic variation largely derived from the female parent B. napus L.. In F2 plants， the morphological and cytological analyses revealed a proportion of plants with the B. rapa-like phenotype carrying 20 chromosomes（ 2n=20， 1.64Ⅰ +9.11Ⅱ +0.04Ⅲ in pollen mother cells（ PMCs） at diakinesis）， as was that of the parental line B. rapa L.. F2 plants carrying 24-28 chromosomes was intermediate for phenotype， while the remaining plants with 29-38 chromosomes showed the phenotype similar to B. napus L.. A few plants containing 38 chromosomes presented low seed-set after self-pollination， and the chromosomes pairing configuration was 0.68Ⅰ +18.23Ⅱ +0.30Ⅲ . The B. napus-like F3 plants were all derived from such F2 plants， and the F2 plants with 2n=35-36 gave ~40% F3 progenies with 2n=38. It could be concluded that the production of the B. napuslike progeny was rational via the directional selection of the F2 plants with such phenotype（ B. napus-like） and cytology（ 2n ≥ 35） . During the PMCs meiosis of F3 plants with 38 chromosomes， the pairing configuration was 0.59Ⅰ +18.30Ⅱ +0.26Ⅲ， and the number of bivalents ranged from 16-19， with mainly 19 Ⅱ accounting for 58.62%， while the number of univalents was from 0 to 3. Compared with F2 plants with 38 chromosomes， the number of univalents and trivalents decreased. In order to study the introgression of parental genetic material in the progenies， AFLP and SSR molecular markers were used for the F2 and F3 generations. The results showed that the A-genome of early maturing B. rapa L. was introgressed in the hybrid progenies of F2 and F3， accompanied by the double variation of A-genome and C-genome of hybrid progenies.

Abstract:Within this study， the phenotypic variations of the quality-related traits were investigated using 62 sweetpotato germplasm resources， which were collected under the frame of the Third National Crop Germplasm Resourses Investigation&Collection Action in Zhejiang province from 2017 to 2019. These traits include the contents of dry matter， carotene and soluble sugars in raw and cooked roots， and taste， followed by statistical analysis using the principal components and systematic cluster analysis. The results showed that 24 accessions were found with high dry matter content， five with carotene content over 5 mg/100 g · FW， seven with soluble sugar content in raw root exceeding that of elite fruit sweetpotato variety Liushiri， and six with maltose content in cooked root exceeding that of mini-sweetpotato variety Xinxiang. Soluble sugars including fructose， glucose， sucrose and maltose were detected in both raw and cooked roots. Especially in raw root， the sucrose was found to be highest， with an average content of 27 mg/g·FW， accounting for 47.49% of the soluble sugar. Relatively， the maltose was the most abundant in cooked roots， and highly associated to the soluble sugar （ r=0.925） . The contents of soluble sugar， reducing sugar and carotene in cooked roots were positively correlated with taste（ P<0.01）， while soluble sugar content in raw root was positively correlated with taste （ P<0.05） . The principal components F1， F2， F3 and F4 were related to edible quality， processing performance of starch and fried chip and sucrose content respectively， which contributed to 94.15% of the variable information of sweetpotato quality. System clustering showed that the quality types of the test germplasm could be divided into three major categories（Ⅰ， Ⅱ ，Ⅲ）， represented by six sub-categories（Ⅰ -1，Ⅰ-2， Ⅱ -1， Ⅱ -2，Ⅲ -1 andⅢ -2） . These accessions， considering the end-use， were categorized： starch type（ 23 accessions）， food and feed dual-use type （ 19）， high quality edible type（ 16）， fried chip type（ 4） . Collectively， the sweetpotato germplasm resources from Zhejiang province were found with an over-representation regarding the starch and food/feed dual-use types， and these germplasms provided a basis in breeding for elite varieties， used for stable food， starch production， whole powder， baked sweetpotato， fried chip， etc.

Abstract:Flowering is a crucial step for the transition from vegetative to reproductive growth in plant’ s life cycle. The character of early-flowering and early-maturing of oilseed rape is the key to solve the conflict between oilseed rape and other summer crops in the multiple-cropping system. Identification of early-flowering oilseed rape and dissecting the basis of early-flowering are conducive to accelerating the procedures of molecular breeding of early-maturing varieties. A novel and stably inherited very-early-flowering oilseed rape Yingchun Yi Hao was evaluated for flowering characteristics in the present study， with 15 sowing stages distributed in nine different months. The results showed that Yingchun Yi Hao sown in the different dates successfully flowered， and unlike common spring type oilseed rapes， was not demanding of low temperature for vernalization. Compared with early-flowering semi-winter line FM4 and late-flowering semi-winter line FM5， Yingchun Yi Hao sown in semiwinter ecological environments in October more rapidly entered the flowering stage， and also was superior in cold tolerance and in general agronomic traits. The molecular experiment revealed that six copies of vernalization key gene BnaFLC on chromosomes A02， A03， C02 and C03 synchronously down-regulated the expression in Yingchun Yi Hao grown in high temperature environment during the vegetative growth stage. 50× whole genome sequencing was performed for‘ Yingchun Yi Hao’ and two reference samples， line FM4 and FM5， which identified 16229 SNPs and 5842 INDELs correlated to 1064 flowering time genes in Brassica napus， and screened out 69 SNPs and 34 INDELs that caused the variation of flowering time genes encoding proteins specific to Yingchun Yi Hao， including 14 SNPs and 4 INDELs that showed positive regulation with BnaFLC， and 11 genes were deduced to be candidate genes for very-early-flowering of‘ Yingchun Yi Hao’ . These genes， except BnaFLC itself， are located upstream of BnaFLC and positively regulate the expression of BnaFLC.

Abstract:Carrot male sterility enables the utilization of hybrid vigor of the crop. Yet the presence of seed hairs of carrot seriously affects the quality and efficiency of seed sowing， and it is usually necessary to remove the seed hairs before sowing. Male sterile material with hairless seed is important for carrot genetic breeding. Carrot Wuye-MG has typical petaloid male sterility and produces hairless seed， was obtained through generations selection from the crossing between the male sterile Wuye-BY selected from the wild carrot Wuye in Hongshan area of Wuhan City， and the selected hairless-seeded Wuye-hairless. In this study， Wuye-MG plants were observed to be dark green， with glabrous and hairless leaves， petioles and stems， and when pollinated by wild carrot Wuye or cultivated carrot Kuroda Gosun， produced fertile hairless seeds， which needed shorter time for germination than either Wuye or Kuroda Gosun. In the fertility mitochondrial gene， Wuye-MG contained the short segment of atp6 gene， but not the long segment of atp6 gene.

Abstract:In order to provide reference for peach fruit evaluation and quality improvement， the aroma components were evaluated using the electronic nose system PEN 3.5 in the fruit of 74 peach varieties. The response values from different sensors were recorded， followed by the analysis of PCA， LDA and LO. LO analysis results showed that four sensors W1W（ hydrogen sulfide）， W1S（ methane compounds）， W5S（ nitrogen oxides） and W2W（ aromatic components and organic sulfides） played a major role in the evaluation of the aroma of the tested peach fruit. PCA results and discrimination values indicated that the aromas of six varieties BaihuaShuimi， Cuibao， Springcrest， Fengguan 1， Ju Huang and Hongroutao 1 were observed with obvious differences with those of other tested varieties. LDA results were differing in peaches with different fruit development periods， i.e.， the methane compounds， aromatic components and organic sulfides were significantly different（ P<0.05） . With the LDA results， the peaches with flesh texture wooliness（ soft） were identified with significant difference（ P<0.05） from the other four flesh types（ non-melting， hard melting， soft melting， and stony hard） . However， LDA was not applied to discriminate flesh colors. The results indicated that： 1） the period of fruit development represented a significant effect on the aroma of peach fruit， 2） peaches with wooliness flesh texture have unique aromas， and 3） the aromas from peaches with different flesh colors are detected without a significant difference.