Genome Wide Association Study Of Grain Water Content And Related Traits In Maize

Maize is the largest cereal crop in China as well as an important industrial and energy crop.With the-restructuring of the agricultural planting mode and the farming system,the demand for the verities suitable for mechanical harvesting with the fast dehydration and low grain water content at harvesting time is becoming more and more urgent.However,in actual production,the grain content at harvesting is very high,which is still a difficult problem to be solved in maize breeding.To provide theoretical assistance for the creation of excellent corn germplasm with fast dehydration and low grain water content,in this study,290 maize inbred lines,which provided by ten institutions form the 13 th Sichuan Maize Breeding Project,were used as experimental materials.Genotyping by sequencing(GBS)was used to analyze the genetic relationship and population structure of inbred populations.Genomewide association analysis was carried out by combining the phenotypic data of grain water content at harvesting time and dehydration traits at two locations in one year.Results are as follows:1.10 inbred lines with grain water content less than 25% and dehydration rate over 1.5%/d were screened out.The material names were SCML17006,SCML17016,NQ231,SCML17100,SCML17112,06H213,78580-494112,SCML17033,Yi13A1 and T213.9 inbred lines with grain water content below 35% at physiological maturity and grain water content below 25% at harvesting were screened,and the material names were cotton Mian0693,SCML17115,Yi14A19,Yi0172,9H1922,SCML17042,SCML17043,3732-3 and Yi018.2.13,697 high quality SNP markers were developed in 290 maize inbred lines by GBS technology.The average distance between adjacent markers is 157 kb,and the linkage disequilibrium(LD)attenuation length on the whole genome is 100-250 kb.Population structure analysis based on SNP molecular markers divided the batch of inbred lines into four subgroups of I,II,III and IV,namely the Tem-tropic group,the Impro-local group,the Impro-tropic group and the MIX group,including 129,42,85 and 34 inbred lines,respectively.3.Using genome-wide association analysis,nine SNP loci which were significantly correlated with the grain water content at physiological maturing were mapped to chromosomes 2 and 5.Four candidate genes Zm00001d003929,Zm00001d013247,Zm00001d014064 and Zm00001d005963 were screened.Among which,the Zm00001d014064 gene was detected simultaneously in both environments.Six SNP loci which were significantly correlated with the grain water content at harvesting were located on chromosomes 1,2,4 and 6,and five candidate genes Zm00001d001837,Zm00001d030833,Zm00001d007838,Zm00001d052361 and Zm00001d038555 were screened.Eleven SNP loci which were significantly correlated with kernel dehydration rate were identified and,distributed on chromosomes 1,3,4,5,6 and 8.Twelve candidate genes were screened,namely Zm00001d042017,Zm00001d042018,Zm00001d042480,Zm00001d052746,Zm00001d052747,Zm00001d052748,Zm00001d017712,Zm00001d012101,Zm00001d028697,Zm00001d034868,Zm00001d021448 and Zm00001d008279.