Identification And Elite Germplasm Screening Of Plant Architecture Related Traits For Early 21^st Wheat In Huang-huai Wheat Area

High yield is the eternal theme of wheat breeding,and reasonable plant architecture is the breakthrough point for improving wheat yield.The natural population composed of 134wheat varieties(lines)in Huanghuai winter wheat area in the early 21st century was used to investigate the plant Architecture related traits,analyze the phylogenetic evolution,and screen the elite germplasm in this study.Based on the developed SNP markers,genome-wide association study was conducted for 30 plant architecture related traits,and the marker related to plant type were obtained to predict candidate genes.(1)Identification of plant architecture related traits.The 30 phenotypic traits variation analysis in 134 wheat varieties(lines)showed significant variation in all traits,with an average coefficient of variation of 17.66%.The variation in the sterile spikelet number per spike was the highest(42.66%),and the variation coefficient in grain weight per spike was the lowest(2.29%).Correlation analysis showed that flag leaf width,second leaf width,flag and second leaf area,stem diameter and spike length were significantly/extremely significantly positively correlated with yield related traits such as thousand grains weight,grain number per spike and grain weight per spike,while plant height and flag leaf Angle were significantly negatively correlated with yield traits such as thousand grains weight,grain number per spike and grain weight per spike.A total of 508 elite germplasm were screened using Jimai 22 as a control.The phylogenetic analysis showed that plant height decreased,stem diameter increased,leaf Angle decreased,leaf area increased,and yield traits such as thousand grains weight also increased over time.The increase in leaf area is mainly due to the increase in leaf width.We proposed an ideal plant architecture model:a semi-dwarf plant of about 80 cm,with erect leaves,short and wide flag leaves,slender second leaf area,a flag leaf area of about 20 cm~2,and an second leaf area of about 23 cm~2,with thick stems and large spikelet.(2)Genome-wide association study of traits related to plant architecture in wheat varieties.Through genome-wide association study,156,295,169,339 and 118 markers were found to be significantly associated with plant architecture,leaf architecture,ear architecture,yield and grain-leaf ratio,respectively,which could explain 14.0%to 32.2%of phenotypic variation,and 348 markers with explanation rates greater than 15%,and detected 13pleiotropic markers associated with three or more traits,including S2D＿587292152.(3)Candidate genes for traits related to plant type.The markers obtained from genome-wide association study were annotated and compared with rice genes,then six candidate genes for plant architecture related traits were identified,namely Traes CS1A02G310700(Nuclear factor Y subunit C),Traes CS2B02G533400(Serine/threonine-protein kinase),Traes CS6A02G351300(Trehalose-6-phosphate synthase),Traes CS6A02G368700(UDP-N-acetylglucosamine),Traes CS6A02G015800(Cytosine-specific methyltransferase)and Traes CS7A02G128300(Histone-lysine N-methyltransferase).