Genome-wide Association Analysis Of Leaf Number And Biomass Of Rapeseed (Brassica Napus L.)

Forage rape has a broad application prospect in China,and the breeding of special(combined)varieties for feed rape is relatively lagging behind.Analyze the genetic diversity of rapeseed germplasm resource biomass and leaf-related traits,establish a comprehensive germplasm evaluation system,and conduct correlation analysis on the biomass and leaf number during the vegetative growth period of the rapeseed germplasms,and discover the genes related to the biomass of forage rape.It is of great significance to the breeding of forage rape varieties.With 395 inbred rapeseed germplasms were collected at home and abroad,the characteristics of biomass and leaf number were investigated in two environments of Wuhan in Hubei and Shihezi in Xinjiang,correlation analysis,principal component analysis and regression analysis.The key characters of vegetative growth were identified by various analyses.At the same time,a mixed linear model was used to perform genome-wide association analysis to identify significant sites related to biomass and leaf number during vegetative growth,and predict candidate genes that regulate rapeseed biomass and leaf number.The main results are as follows:1 The genetic variation of dry matter accumulation rate after bolting stage is abundant.Comparing the traits of the core collection under two different environments,it was found that the genetic variation of the rape population at the Wuhan was greater than that of the Shihezi,the genetic variance of the flowering stage biomass was smaller than that of the Shihezi,and the genetic variance of the leaves number was more abundant than that of the Shihezi.There are differences in the distribution frequency of biomass and the number of genotypes of each type of leaf between Wuhan and Shihezi.Principal component analysis classified 13 first-level indicators into 5 principal components,with a cumulative contribution rate of 84.77%.Stepwise regression analysis was used to screen out 7 traits,including dry weight at bolting stage,fresh weight at bolting stage,fresh weight at flowering stage,total number of leaves at bolting stage,short-petiole leaves number at bolting stage,total number of leaves at flowering stage,and less-petiole leaves number at flowering stage.The key indicator of growth during vegetative period.2.The phenotypic traits of population materials were analyzed using a mixed linear model for genome-wide association analysis.A total of 14 significant sites related both bolting stage and flowering stage biomass were detected;and 47 significant sites related bolting stage various types of leaves number were detected,A total of 25 significant sites related total number of leaves at bolting stage were detected,6 and 2 significant sites related green leaf number and fallen leaf number at the bolting stage were detected.A total of 6 and 8 significant mutation sites were detected respectively related shortpetiole leaves number and long-petiole leaf number at the bolting stage were detected.A total of 11 significant variation sites related various type leaves number at the flowering stage were detected.:the green leaves number at flower stage,fallen leaves number at flowering stage,total number of leaves at flowering stage,and short-petiole leaves number at flowering stage were 3,2,2,and 4.3.According to association analysis,candidate genes related to biomass and leaf number were screened in the range of 150 kb upstream and downstream of significant association sites.17 genes are related to fresh weight at the bolting stage,including genes related photosynthesis regulation,auxin signal activation pathway,auxin binding and positive regulation of cell metabolism.49 genes are related to dry weight at bolting stage,including genes related to the composition of cytoplasmic vesicles,the response of cells to non-biological stimuli,the activity of protein dimers,and the response of organic cyclic compounds.34 genes are related to fresh weight at flowering stage,genes related to negative regulation of nutrient level response,regulation of nitrogen compound metabolism,and disulfide oxidoreductase activity.35 genes are related to dry weight at flowering stage,including genes related to cytoplasmic exosome composition,polysaccharide biosynthesis,and defense response to bacteria.51 genes are related to the number of green leaves at bolting stage,including genes related to leaf development,cytoplasmic exosomes composition,xylan metabolism process,mitochondrial composition,and monocarboxylic acid metabolism.5 genes are related to the number of fallen leaves at bolting stage,including genes related to the negative regulation of cell senescence metabolism and purine glyconucleotide metabolism.44 genes are related to total number of leaves at bolting stage,including genes related to anion transmembrane transporter activity,carbon utilization,leaf morphogenesis regulation,carbohydrate transport,and carbohydrate biosynthesis processes.30 genes are related to the number of short-petiole leaves at total number of leaves at bolting stage,including genes related to cell wall pectin metabolism,response to nutrient levels,and regulation of reproductive processes.30 genes are related to the number of longpetiole leaves at bolting stage,including genes related to negative regulation of the abscisic acid activation signal pathway,ribulose bisphosphate carboxylase activity,and redox process.22 genes are related to the number of green leaves at flowering stage,including those related to temperature stimulation and the composition of cytoplasmic exosomes.15 genes are related to the number of fallen leaves at the flowering stage,including genes related to abscisic acid transport and abscisic acid biosynthesis.14 genes are related to the number of short petiole leaves at the flowering stage,including genes related to the response to light stimulation and the process of cytokinin biosynthesis.