QTL Analysis Of Resistance To Head Smut In Maize

Clint,which is also one of the main diseases of Spring Maize in China.The resistance of Maize to head smut is a quantitative character.Breeding and planting resistant and resistant varieties is the most economical and effective way to control the disease,while MAS can improve the breeding efficiency and provide basis for large-scale cultivation of fine lines or varieties.In this study,the F₂ and F_2:3 populations of high resistance inbred line T32 and susceptible inbred line HC were used as mapping and disease resistance evaluation populations.The genetic linkage map was constructed by SSR molecular markers.The disease resistance was identified in Huaxi District and Guian New District of Guiyang City,Guizhou Province,and the disease resistance QTL was analyzed by using the method of ICIM.Closely linked molecular markers provide theoretical basis for MAS.The main results are as follows:1.A genetic linkage map containing 145 SSR markers was constructed with the F₂ population?159 individual plants?ofas the mapping population.The markers were distributed in 10 linkage groups,covering 1103.355 c M of maize genome,and the average distance between markers was 7.609 c M.2.In Guian new district,three QTLs were detected on chromosomes 1,6 and 9respectively,explaining 6.29%-16.02%of phenotypic variation.Five QTLs were detected in Huaxi district,which were located on chromosomes 1?2?,3,4 and 6respectively,explaining 5.10%-12.91%of phenotypic variation.Combined with the location results of the two sites,two QTLs were detected.One was located on the first chromosome?bins 1.01?and was labeled umc1177-umc2224,the gene action mode was over dominance.The other was located on the sixth chromosome?bins 6.02-6.05?and was labeled umc1006-nc013,the mode of gene action was dominance and partial dominance.The two QTLs had higher LOD value and higher phenotypic contribution,and the synergic genes were all from T32.3.The combined QTL analysis was performed on the field identification results of the two test sites.A total of 10 QTLs were detected,located on chromosomes 1,2,3,4,5,6,and 9.The QTL LOD value was 2.03-5.86,and The LOD of environmental interaction is 0.01-0.47.The two QTLs expressed simultaneously at two experimental points in the single environment analysis were also detected in the joint analysis,and also in the same labeled segment.The LOD value and contribution rate were also significantly higher than other QTLs.4.The modes of action of QTLs detected in this study are mainly two types of partial dominance and over dominance.