Fine Mapping Of Main QTL For Gray Leaf Spot Resistance In Maize Inbred Line T32

Maize gray leaf spot(GLS)is a worldwide fungal non-soil-borne disease.The occurrence and epidemic of gray leaf spot seriously affects corn production.Previous studies have shown that breeding resistant varieties is the most economical and effective way to control gray leaf spot.In the earlier research,with the high resistance to gray leaf spot inbred line T32 and the high-sensitivity of gray leaf spot inbred line J51,our group located the QTL against gray leaf spot on the chromosome 8 of the umc1130-umc2354,and the physical distance was 113.9Mb.Based on the results of previous studies,the disease-resistant inbred line T32 was used as the donor parent,and the susceptible inbred line J51 was used as the recipient parent.BC3F2 was constructed by backcrossing and selfing,combined with foreground selection and background selection.The isogenic line population performs fine mapping of the target QTL.The results are as follows:(1)Validation of QTL(designated QTL-GLS8)locus for control of maize gray leaf spot on chromosome 8 using a small population of BC3F2(designated BC3F2-Micro)comprising 180 individuals,and further localization using published SSR markers Marked between CSU329-umc1034,the physical distance between the two markers was 1102 kb.(2)Using the Join Map 4 and QTL-Icimapping software and newly developed 8 pairs of polymorphic primers in the target segment to locate the main QTL-GLS8.In 180 individual plants of the BC3F2-Micro population,the major QTL-GLS8 was mapped between the markers ym20-ym31 with a physical distance of 272.826 kb.In 1468 individual plants of the BC3F2 population,the major QTL-GLS8 was finely defined between the markers ym20-ym51 and the physical distance was 124.232 kb.The results of the localization analysis were further verified by using the exchanged plants of the BC3F2-Micro population and the BC3F2 population.Through the fine mapping of maize leaf inbred line T32 against gray leaf spot gene QTL-GLS8,it provides a new theoretical reference for maize disease resistance breeding practice and molecular marker-assisted breeding,for subsequent gene cloning and functional verification.And further explore candidate genes to accelerate the breeding process of maize resistance to gray leaf spot.