Putative genes for resistance to gray leaf spot of maize based on genomic resequencing using recombinant inbred lines

Abstract

AbstractGray leaf spot (GLS) of maize (Zea mays L.), caused by Cercospora spp., inflicts serious yield losses. Four recombinant inbred lines (RILs) were developed from the [(YML32×Q11) × Q11] backcross population. Two flanking markers, GZ204 and IDP5, defining quantitative trait locus (QTL) qRgls1 for resistance to GLS, were detected in three RILs (RL1_1, RL1_2, and RL2_1) but not in RL2_2. This QTL is located on chromosome 8 in bin 8.02. The field resistance of RL2_2 was, however, similar to that of RL1_1 and RL1_2. The RL2_2 was found to possess a unique DNA segment (Zm00001d008467) that was not found in the other three RILs. We tested the hypothesis that Zm00001d008467 is a candidate gene associated with resistance to GLS. Sequencing showed that clean read counts for RL1_1, RL1_2, RL2_1, and RL2_2 were different and that single‐nucleotide polymorphisms (SNPs)/Exonic SNPs in RL1_1, RL1_2, RL2_1, and RL2_2 were 4908618/14042, 2423243/10668, 4512193/12577, and 2321974/6731, respectively. Results revealed that one of the three exclusive extron nonsynonymous SNPs (Zm00001d008467_T003) had caused a change in a protein that is a wall‐associated non–arginine‐aspartate (non‐RD) receptor‐like kinase. This protein is suspected to trigger resistance to GLS. Our results confirm that Zm00001d008467 is a candidate gene, located in chromosome 8 in bin 8.02, that is associated with GLS resistance. We concluded that the exclusive extron nonsynonymous SNPs in the QTL that had changed the structure and function of the coding protein was responsible for the GLS resistance in RIL2_2 in the absence of resistance QTL qRgls1.