Genetic Analysis Of Leaf Chlorophyll Decay Rate In Maize (Zea Mays L.) Northeastern Core Germplasm Associated Population

Maize(Zea mays L.)is most widely grown cereal crop in the world.At present,we have confronted with the shortage of food.It is urgent to increase the production of maize.Photosynthesis of maize leaves plays an important role in increasing grain yield.The absorption,transmission and transformation of leaf chlorophyll to light energy is the first step of photosynthesis.The change of chlorophyll content will directly affect the intensity of photosynthesis.In the middle and late stages of maize filling,the attenuation of chlorophyll content affects the grain filling degree seriously.Therefore,this study used 522 populations of germplasm as material from the core of northeast in China.we have planted these material in Liaoning province and Hainan province,and have analyzed the 552 materials of chlorophyll of leaves' decay rate(CDR)by genome-wide association analysis(GWAS).We have screened candidate genes which affected changes in the content of chlorophyll,and performed functional analysis of candidate genes to identify candidate genes which can increase photosynthetic capacity by reducing CDRs.Thus,affecting grain yield,and providing theoretical value with the production of high-yield and quality maize varieties.The main results of this study are as follows:Analysis of CDRs on leaves in two different of environments in China revealed that have no significant differences in CDR distribution between Hainan and Liaoning province.However,the BLUP value of Hainan province is significantly different from Liaoning province.It is mainly estimated that the environment has an effect on CDR.The composition of variance and heritability analysis of the CDR showed that the CDR heritability was 0.53.And it meant moderate heritability,indicating that the environment of has less effect,and the main factor of changes on CDRs was the gene.The correlation analysis of CDR in environment of Liaoning and Hainan province showed that the CDR and BLUP values of each environment were normally distributed,which were in accordance to quantitative traits.This paper have reported that both significant positive correlation in CDR and BLUP between Hainan and Liaoning province with R of 0.71 in hainan and R of 0.79 in liaoning,respectively.The results showed that GWAS can proceed smoothly.The analysis of GWAS showed eleven significant related SNPs in a single environment,including 5 in Liaoning province and 6 in Hainan province;it was identified that a total of 54 candidate genes,which were divided into five categories: transcriptional regulation(13%),material transport(5%),signal transduction(32%),metabolic pathway(17%),and unknown pathway(33%).There are 9 candidate genes related to CDR,respectively GRMZM2G405368,GRMZM2G161664,GRMZM2G016477,GRMZM2G152135,GRMZM2G150213,GRMZM5G894619,GRMZM2G104676 and GRMZM5G826216,and there is a candidate gene(GRMZM2G044968)that has a direct influence on the CDRs of the ear leaves.