QTL Indentification For Resistance Of Common Smut

Common smut is a kind of local infection disease,which has been prevalent in northeast China,north China and Huang-Huai-hai area in recent years,which seriously threatens the yield of maize.Breeding of disease-resistant germplasm resources is an effective way to control the common smut.In this study,300 recombinant inbred lines(RIL)were constructed using resistant inbred lines Qi319 and susceptible inbred lines Ye478,respectively.In 2015 and 2016,the field natural inoculation was used in the group families,and the artificial inoculation was used in 2017.Based on the genomewide SSR linkage map,the mapping of QTL was performed using the complete interval mapping method in the mapping software,and the location interval was validated by selecting the fragment substitution system on the target chromosome.The main findings are as follows:(1)RIL Group Field performance: Two parents and RILs in 2015,2016 and 2017 planted in the experimental base of Shenyang Agricultural University,high incidence of disease plots,and rigorous investigation of the incidence of each family.Using Microsoft Excel 2013 software,a normal distribution test was performed for the disease level of 300 families in the RIL population.The results show that the disease grade of 2015 and 2016 are mainly distributed in Grade 7,and the disease grade of 2017 is mainly distributed between Grade 7-9 levels.(2)QTL mapping of common smut: Using 600 pairs of SSR primers to analyze the polymorphism of Ye478 and Qi319,the 192 markers with polymorphism of two parents were,and the total number of primers was 32%,and the linkage marker was constructed by using these 192 primers.The maize genome was covered by 2721.25 cm,with an average distance of 14.17 cm.The relative order of the markers on the 10 chromosomes is essentially the same as that of the MaizeGDB,but there are cases where the positions of the few two markers are reversed,but their chromosome regions do not change.Using the ICI mapping software for QTL mapping,the results showed that: In 2015,one maize resistant QTL were detected in Chr3,it accounted phenotypic contribution rate 6.5752%.In 2016,two maize resistant QTL were detected in Chr2 and Chr3,respectively,they accounted phenotypic contribution rate is 4.7297%~5.6229%.In 2017,three maize resistant QTL were detected in Chr3,Chr9 and Chr10,they accounted phenotypic contribution rate was 5.5743%~7.6128%.The QTL for bins 3.07 in the 2016 and 2017 were consistent QTL,which explained 4.7297% and 7.6128% of the phenotypic contribution,respectively.(3)Using the fragment substitution system on chromosome 3 to verify the 17qCS-3: 13 chromosome fragment substitution on chromosome 3,which was constructed by Ye478 and Qi 319,was planted in 2017 at the experimental base of Shenyang Agricultural University.By using the artificial inoculation to identify the common smut resistance of the group,the Bin3.07 position of the initial location was validated by the Independent Sample T test,the result showed that the fragment substitution system containing the marker umc1489 genotype could significantly improve the resistance of common smut.