Analyze The Genetic Basis Of Leaf Chlorophyll Decay Rate In Maize By GWAS

At present,the growth of total maize production in China has entered a bottleneck stage due to the limitation of planting area,and the effective method to solve the problem of lack of stamina in China's maize production growth is to cultivate excellent varieties with high yield per unit area.Changes in chlorophyll content of corn leaves during grain filling will affect their photosynthetic efficiency and thus affect the final yield.In this study,the genomic association analysis was used to study the chlorophyll decay rate of maize leaves in Liaoning and Hainan.The candidate genes involved in the regulation of chlorophyll decay rate were initially screened,and the relationship between environmental changes and candidate genes was further analyzed.It provides a certain theoretical basis for the cultivation of good maize varieties suitable for planting environment.508 corn inbred lines were used as experimental materials.They were planted in Sanya,Hainan,and Shenyang,Liaoning,in November 2015 and May 2016,respectively,with two replicates in each region.Using the SPAD-502 chlorophyll meter to determine the change in chlorophyll content during leaf senescence,the decay rate of chlorophyll from the leaf was calculated.The difference in corn chlorophyll decay rate between the environments of Hainan and Liaoning was used as a measure of environmental impact on the phenotype of the inbred line.Based on the phenotypic data between the two environments,the best unbiased linear prediction(BLUP)calculated by the mixed linear model is used as the data to eliminate the environmental impact.The preliminary data analysis of the two environmental chlorophyll decay rates,BLUP values,and the differences between Hainan and Liaoning were conducted,and the variance components of corn chlorophyll decay rate were calculated to have broad heritability;According to the mixed linear model(MLM),four groups of data were analyzed by association analysis to determine the significant SNP;Reference B73 v2 sequencing results and gene annotation screen for candidate genes linked to significant SNP loci.The chlorophyll decay rate,BLUP value,and the difference between the two environments in Hainan and Liaoning showed a normal distribution,and the genotype,genotype,and environment interactions all showed extremely significant,and the broad sense heritability was 40%.The inter-phenotypic analysis results were all associated with similar groups,with significant differences between them.Correlation analysis of the two environmental chlorophyll decay rates in Hainan and Liaoning revealed 12 and 21 significant loci,respectively,and 16 and 31 candidate genes were screened out respectively;17 and 34 significant loci were found for BLUP values and differences,respectively.Candidate genes are 20 and 47.The four data candidate genes were mainly related to signal transduction,followed by 43.75%,32.26%,38.10%,and 51.06%,respectively.These genes can be classified into signal-sensitive correlations that reflect changes in ambient temperature,light,and reactive oxygen species in the body;It is related to the signal transduction of synthesis and transport of various hormones;it is related to the three types of receptors involved in polysaccharide transport,transcriptional regulation,and protein receptor degradation.The signal transduction genes associated with the difference are mostly signal receptors and signal receptors.Maize mainly regulates the leaf chlorophyll decay rate through signal transduction pathways.The influence of environment on the phenotype of inbred lines is related to the sensitivity of signal transducers and signal receptors in the signal transduction pathway.