Identification Method Of Cold Resistance In Wheat Seedling And Genome-wide Association Analysis Of Correlative Traits

Wheat is one of the most important food crops in the world.Low temperature stress is an important abiotic stress constraint on wheat production.With the rapid development of molecular biology and its wide application in production,identification and screening of molecular markers associated with resistance to cold have advanced the cold-resistant breeding process in wheat and provided a molecular marker-assisted selection for wheat cold-resistant breeding.In this study,543 wheat natural populations were used as the research materials to identify the cold resistance of wheat at the seedling stage.The population structure,linkage disequilibrium and relationship of natural populations were analyzed by the method of whole genome association analysis.The molecular data obtained by high through put sequencing technology were associated with the cold resistance evaluation phenotypic data to screening SNP with significant correlation with cold hardiness.At the same time,the temperature of low temperature stress suitable for the identification of cold resistance of indoor wheat was studied,and the variation regularity of various indexes under different low temperature stress conditions was analyzed and compared.A set of method for identifying cold resistance of indoor wheat with good reproducibility,strong maneuverability and high accuracy was found out in combination with the data of cold resistance index in the field.The main results are as follows:1.The freezing survival rate of wheat treated with freezing temperature?-14°C?for 3 hours at room was significantly negatively correlated with the investigation data of field freezing injury level?r=-0.427?.According to the survival rate of frozen wheat after cryogenic treatment for 3 hours,the degree of freezing damage of wheat can be judged,and then the cold resistance of wheat can be identified.2.Under the condition of controlling the population structure and the relationship between materials,3 cold resistance traits of 11140 SNP and 543 wheat germplasms were analyzed by a mixed linear model,and 75 SNP loci which were significantly related to the cold resistance of wheat were detected were distributed in 1B,1D,2A,2B,2D,3A,3B,3D,4B,4D,5A,5B,5D,6B,6D,7A,7B and 7D chromosomes of wheat.Among them,there are the most numerous loci on 2B and 5A chromosomes,with 8 loci,and the number of locus on chromosomes 5B and 7B is more,which is 7 loci.The most contributing SNP marker?BS00044895₅1?is located on chromosome 7A.It can explain 18.70% of the phenotypic variation,and the least contributing SNP marker?Ra_c2964₂254?is located on chromosome 3D,which can explain 3.50% of the phenotypic variation.3.The trait of frost damage grade in 6 environments detected 63 cold-resistance-related SNPs totally.The contribution rate range was 3.51%?IACX 5971,Ex_c52589₇95?-14.91%?wsnp_CAP11_c2435₁256981?.The trait of mortality rate of tiller in 4 environments detected 56 cold-resistance-related SNPs totally.The contribution rate range was 3.50%?Ra_c2964₂254?-18.70%?BS00044895₅1?.The trait of withered leaves rate in 4 environments detected 42 cold-resistance-related SNPs totally.The contribution rate range was 4.04%?RAC875_c45166₁174?-16.54%?BS00044895₅1?.4.Searches of public databases revealed 23 putative candidate/flanking genes related cold tolerance.These genes were grouped in 5 categories by the types of function:defense response proteins?Stb6,BTR1,LR1?,enzymes?WAK,hemH,Acc-1,Acc-2,CKX2.4,CKX2.5,GT47-2A,cytochrome P450?,promoters and transcription factors?ERF1,PHR1-B1,CBF10,TaAP2-A,TaAP2-D,SNF2P?,storage proteins?Glu-Dty,ACT-1,Gli-D2,Glo-2?and response to vernalization?Vrn2,ZCCT1,ZCCT2?.