Analysis Of Genetic Basis Of Maize Kernel Dehydration Traits During Physiological Maturity Using GWAS

Maize is the most widely cultivated kernel crop in China,and it is also the most important economic crop in China.With the popularization of agricultural mechanization,the whole process mechanization of maize planting has become a universal trend,and most areas of our country have achieved the mechanization of maize production.However,the moisture content of maize kernel as the most important factor limiting the mechanization of maize harvest,reducing the moisture content of maize kernel at harvest time has become the most concerned problem for breeders.Therefore,the cultivation of maize varieties with fast dehydration rate and low moisture content at harvest have become the main task of maize breeding.Because the maize kernel dehydration is controlled by multiple genes,the traditional breeding method has a long cycle and requires many years of artificial breeding.Previous studies mainly focused on phenotypic traits related to dehydration rate.Therefore,it is of great significant to find out the genes controlling maize kernel dehydration rate by genome-wide association analysis.In this experiment,522 maize inbred lines with wide polymorphism were used to construct a natural population.The moisture content of maize kernel at the occurrence of black layer and at harvest time was measured,calculating the rate of dehydration of maize kernels during physiological maturity.The results provided a theoretical basis for finding maize varieties with fast kernel dehydration rate and low moisture content after physiological maturity by finding out candidate genes controlling maize kernel dehydration rate.The main results of this study are as follows:1.Genetic basis of Maize Kernel Moisture content in Associated populationThe phenotypic data of maize kernel moisture content was measured in Shenfu Liaoning Province and Ledong Hainan Province during at the occurrence of black layer and at harvest time.The phenotypic data of moisture content were analyzed.The phenotypic data of maize kernel in Shenfu Liaoning and Ledong Hainan showed normal distribution.The heritability in the two environments were 0.61 and 0.62 respectively showing moderate heritability.When the threshold value was set to 4,three SNP loci were detected on chromosome 7 and chromosome 10,respectively.A total of 7 functional annotated gene locus were identified as anabolism,signal transduction,redox reaction,transcriptional regulation,and secretion directly or indirectly affect the moisture content of maize kernel.2.Genetic basis of Maize Kernel dehydration rate in Associated populationThe moisture content of maize kernel at the occurrence of black layer and at harvest time was measured,calculating the rate of dehydration of maize kernels during physiological maturity.The normal distribution test of the dehydration rate was carried out by SPSS software,the results showed that: The dehydration rate at the physiological maturity stage of maize is a normal distribution,which belongs to the quantitative character and the broad heritability is 0.31.With correlation mapping of the dehydration rate of maize kernel in Shenfu,when the threshold value was set to 4,11 SNP were detected on chromosome 1,7,9 and 10,respectively.With correlation mapping of the dehydration rate of maize kernel in Ledong,Hainan,when the threshold value was set to 4,4 SNP locus were detected,which were located on chromosome 7 and chromosome 10 respectively.With correlation mapping of the dehydration rate of maize kernel in two environments,when the threshold value was set to 4,a total of 3 SNP locus were found,both of which were located on chromosome 7.A total of 46 Gene locus were identified,including anabolism,signal transduction,redox reaction,transcriptional regulation,and secretion,which directly or indirectly acted on the dehydration rate of maize kernel.