Resistance Identification And Association Analysis Of Resistant Genes To Maize Ear Rot

Maize(Zea mays L.)was the food and feed crop with the highest total yield and the largest planting area in China.Maize ear rot was a kind of fungal disease that was difficult to control occuring in the late growth stage of maize.It was found that the most fundamental and effective way to control the disease was to cultivate and plant resistant varieties.Under the condition of artificial inoculation,277 inbred lines from home and abroad were identified and evaluated for resistance to two dominant pathogens of maize ear rot(Fusarium verticillioide and Fusarium graminearum),and the resistance materials with single and double resistance to two dominant Fusarium were selected.Affymetrix SNP 56 K chip(including 56110 SNP markers)was used to analyze the genotype of the inbred lines.Based on the analysis of population structure and genetic relationship,genome-wide association analysis was used to locate the genes related to ear rot resistance.And combined with bioinformatics,the important sites related to ear rot resistance were analyzed,which laid a foundation for further understanding the mechanism of ear rot resistance and promoting the molecular breeding process of ear rot.The main results were as followed:(1)The resistance of 277 maize inbred lines to Fusarium ear rot was evaluated by inoculating two kinds of pathogens.The results showed that there were 277 effective identification materials for inoculating Fusarium verticillioide,26.72% of them were medium resistance,23.10% of them were disease resistance,16.61% of them were high resistance;226 of them were effective identification materials for inoculating Fusarium graminearum,14.16% of them were medium resistance,8.85% of the inbred lines showed resistance,4.87% of the inbred lines showed high resistance;16 of the inbred lines showed resistance to both pathogens,accounting for 7.08% of total inbred lines.(2)After strict quality control,20775 high-quality SNP markers were screened.Combined with the phenotypic data and considering the population structure and genetic relationship,genome-wide association analysis was implemented by using the MLM model in Tassel 5.0 software.Under the standard of significance level P≤0.001(-lgP≥3),15 SNP markers were obtained which were significantly related to the resistance to Fusarium verticillioide ear rot and located on chromosomes 1,2,3,4,5,7 and 8 respectively;13 SNP markers were obtained which were significantly related to the resistance to Fusarium graminearum ear rot and located on chromosomes 1,2,4,7 and 9 respectively;the SNP marker AX86264994 located in bin 1.05 was identified by both pathogens.(3)According to the related annotation documents of SNP markers,11 out of 15 SNP markers related to Fusarium verticillioide ear rot resistance were found to be located within the gene,four in the gene interval region,and three candidate genes with known functions were obtained;nine out of 13 SNP markers related to Fusarium graminearum ear rot resistance were located within the gene,four on the gene interval region,and five candidate genes with known functions were obtained.