Indentification And Fine Mapping Of A Major QTL For Resistance Of Gray Leaf Spot In Maize

The maize gray leaf spot caused by the infection of maize leaves by Cecrospora zeae-maydis has become one of the important diseases in the China’s east and Southwest corn producing areas.Is a cost-effective way to explore the resistance to gray leaf disease gene and used in disease breeding varieties breeding.In this paper,the QTLs of maize resistance to gray leaf spot were collected and sorted,and the meta-QTLs were analyzed by meta-analysis.Then the Segment Substitution Lines grouped by CN165 donor donor and 81162 for recipient parents were used to verify meta-QTL and explore the major QTL.Filter the separation population containing the target segment to fine mapping the QTL.The main conclusions are as follows.The 14 QTLs were sorted by meta-analysis.A total of 13 meta-QTLs were identified and distributed on the chromosomes 1,2,4,7 and 8.Use the 81162 as the recurrent parent and CN165 for the non-recurrent parent to construct the backcrossing population.Using this population,13 consistent QTLs were validated according to the linkage disequilibrium principle,and 20 partial segregation sites were obtained in 13 consistent QTLs.The partial segregation of chromosome 1 and 4 are the most serious,whire the others are small.It means that there are greater resistant QTL on the 1st and 4th chromosomes.The genotype frequencies of umc2227;bnlg1832,umc1243,umc2025,umc1515,umc1297 and umc1461 were more than 50%.and there might be several linkage genes.The gene on chromosome 4 is located between marker bnlg2291 and umc1194.Based on the background test results,three target families were selected from the BC2F3 resistant families and crossed with the reincarnation parent 81162 to obtain the target group.A total of 176 individuals from the same self-pollinated ear were selected to locate the major QTL-CNgls 4 of chromosome 4 by complete interval mapping.The QTL was located between marker umc1329-bnlg1137.The 67 primers were independently developed according to the B73 sequence information,and the 7 polymorphisms were obtained in the target region.882 high resistance and 37 high susceptibility individuals from BC3F2 population were screened for recombinant plants,and 11 recombinations were found in this interval.The QTL interval was fine-mapped between the markers Snyw042 and Snyw008,the physical distance was 2.19 Mb,and the physical location was 167,355,376 bp-169,548,333 bp.The main QTLs of chromosome 4 in inbred lines CN165 were used to provide a theoretical reference for breeding clonal and functional analysis of germplasm materials,maize molecular marker assisted selection breeding and resistance to gray leaf spot genes.