Genome-wide Association Studies Of Genes Controlling Shoot Regeneration Ability Of Maize

Shoot regeneration ability is considered the base of genetic transformation.Immature embryo is usually used as an explant for maize genetic transformation.Genotype is one of factors influcing shoot regeneration.The report about genes influencing maize shoot regeneration was limited.So,it was important to find the genes involved in regulation of shoot regeneration,which will be helpful to improve the genetic transformation efficiency and expande an understanding of the molecular mechanism of shoot regeneration.Immature embryos at 11 DAP of 367 maize inbred lines were harvested and used as explants to examined the shoot regeneration ability.Six traits related with tissue culture,such as percentage of primary callus(PPC),percentage of mature callus(PMC),status of callus(SC),proliferation of callus(PC),percentage of shoot regeneration(PSR)and number of regenerated shoots per callus(NS),were recorded and analyzed in the summer of 2013 and 2014.Candidate genes were detected by genome-wide association study(GWAS).The key results were as follows:(1)Immature embryos at 11 DAP of 367 maize inbred lines were cultured and the phenotype data during tissue culture were harvested.There was significant variation among 367 maize inbred lines.Genotypes affect capability of plant regeneration.Some inbreds have high shoot regeneration efficiency,for example,CIMBL3(75%),CML426(65.5%)and CML323(64.5%).However,the shoot regeneration efficiency of some inbreds were very low.(2)Based on the GWAS results,132 SNPs were found to be associated with tissue culture process.Fifty-eight candidate genes were associated with these SNPs and these candidate genes may play a role in tissue culture.(3)The results of correlation analysis showed PPC significantly was correlated with PMC.But there was no obvious correlation between PPC and PSR.PC also was correlated with PSR.It was suggested that callus induction and shoot regeneration were controlled by different genetic factors.(4)Four genes were selected to analysis function in shoot regeneration.Overexpression of GRMZM2G138689 has no influence on the percentage of shoot regeneration.Overexpression of GRMZM2G074850 and GRMZM2G045404 can increase percentage of shoot regeneration.However,overexpression of GRMZM2G168393 decreases percentage of shoot regeneration.