Identification Of Excellent Allelic Variations On Drought Tolerance In SNAC Genes Of Maize

Drought is the abiotic factor that has the greatest negative impact on the production of food crops worldwide.The annual damage caused by drought is greater than that caused by other abiotic stresses such as salinity,high temperature and low temperature.Maize is particularly sensitive to drought stress as a crop with large water requirement during the whole growth period.Therefore,by exploring the excellent allelic variation of drought-tolerant related genes,we can cultivate varieties with higher drought-tolerance,so as to improve the yield of Maize under drought stress.In this study,210 maize inbred lines with wide genetic basis were used to construct association analysis population,and the SNAC family genes in the genome were cloned and sequenced by the first generation Sanger sequencing.Candidate-gene association analysis and T-test were used to identify SNP and In Del loci significantly associated with drought tolerance in maize,as well as superior allelic variations with drought tolerance.Excellent drought tolerance allelic variations and haplotypes were identified based on the analysis results.It provided theoretical basis for improving drought tolerance of Maize by molecular breeding.The main results are as follows:1 The maize SANC family genes Zm NAC070395,Zm NAC030295 and Zm NAC020303 were deeply sequenced and the polymorphic loci with frequencies less than 10% were excluded.A total of 33 mutation sites were detected in Zm NAC070395,including 25 SNPs and 8 In Del;68 mutation sites were detected in Zm NAC030295,including 41 SNPs and 27 In Del;and 9 mutation sites were detected in Zm NAC020303,all of which were SNPs.2 Linkage disequilibrium analysis of maize SANC family genes Zm NAC070395,Zm NAC030295 and Zm NAC020303 was carried out by TASSEL 5.0 software.Linkage disequilibrium existed in all the above genes,and the degree of linkage disequilibrium was high.3 By using MLM model in TASSEL 5.0 software,15 significant loci including 13 SNPs and 2 In Del were found in Zm NAC070395,and one significant locus was found in Zm NAC030295 and Zm NAC020303 respectively,both of which were SNPs.4 Fifteen inbred lines with excellent allelic variation at significant loci were screened out in combination with previous laboratory studies.The results showed that the agronomic traits of 15 inbred lines under drought stress were significantly higher than those of other inbred lines,which verified the accuracy of the results.