Genetic Analysis Of The Maternal Haploid Induction Rate Of Maize Haploids And Their Associated Ear Traits

Maize is an important grain crop in China,as well as an indispensable raw material for industry,and has an important impact on China’s food security.The identification of QTL controlling maize cob length and cob diameter traits will not only help to reveal the genetic mechanism of maize yield,but also guide maize breeding practice.Double haploid breeding techniques have been widely used in commercial breeding at home and abroad.At present,the main way to obtain haploids in maize is to induce haploid production by maize solitary reproduction,and most of the current research focuses on the study of maternal haploid induction rate.Genome-wide selection of two traits,cob length and cob diameter,can provide important reference information for breeders.In this study,the F₂ population of B73 and Zheng 58 was used to make genome-wide selections for the three traits of cob length,cob diameter and maternal haploid induction rate.The main results were as follows.1.A genetic linkage map was constructed using 1855 SNP markers with a total map length of 2788 cM and an average marker spacing of 1.6 cM.2.A total of 12 QTL controlling the induced rate were detected at the three environmental sites.qMHI5-1,located on chromosome 5,was detected at both the E1 and E2environmental sites.3.A total of eight QTL controlling cob diameter were detected at the three environmental sites.qCD4-1 was detected at the E1 environmental site with the highest effect value and10.66%phenotypic contribution,which was also detected at the E3 environmental site.4.A total of nine QTL controlling cob length were detected at the three environmental sites.qCL3-1,located on chromosome 3,had an LOD value of 5.5 and a phenotypic contribution of 10.6%.5.The prediction accuracy of cob length and cob diameter were 0.56 and 0.39,respectively,with moderate selection accuracy.Good selection accuracy was obtained when the number of markers reached 500;good selection accuracy was obtained when the training population contained 60%of the total genetic variation of the population.6.A total of four main effect QTL were detected,qCD4-1,qCL3-1,qCL4-1 and q MHI5-1.qCD4-1,qCL3-1 and q MHI5-1 were detected in different environments and can be considered as stable main effect QTL,and these QTL can provide intervals for fine localization.