QTL Analysis Of Resistance To Head Smut Caused By Sphacelotheca Reiliana (K(?)hn) Clint In Maize

Head smut of com is a cosmopolitan disease. It causes a significant yield losses and quality, degradation especially in spring maize area. Development of varieties or hybrids resistant to this disease is one of the effective approaches to control the disease. Molecular marker technology will contribute to explore the useful information in efforts to develop resistant germplasm efficiently through locating the QTL relevant to diseases resistance. In this study, we mapped and characterized quantitative trait Loci (QTL) conferring resistance to head smut. A mapping population (F2) with 191 individuals was derived from the cross of two elite inbreds (Mo 17 and Huangzao4), and the corresponding 184 F3 families (7 missed) were evaluated for head smut resistance with two replications in Jilin and Heilongjiang provinces, respectively. The F2 population was genotyped with 49 AFLP and 91 SSR markers, and QTL analysis was performed with composite interval mapping (CIM). The main results are as follows:(1) A genetic linkage map with 84 SSR and 48 AFLP markers were constructed, spanning maize genome 1542.9cM with average distance of 11.7cM between adjacent markers.(2) In Jilin, 5 putative QTL conferring resistance to head smut were detected on chromosomes 1, 2, 3, 8 and 9, respectively, accounting for 10.0% to 16.3% of the phenotypic variation. In Heilongjiang, 5 putative QTL conferring resistance to head smut were detected on chromosomes 1, 2, 3, 4 and 7, respectively, accounting for 4.6% to 13.45% of the phenotypic variation. Pooled analysis based on the two environments was conducted, and 6 putative QTL were detected on chromosomes 1, 2, 3, 4, 8 and 9, respectively, explaining 4.6% to 15.3% of the phenotypic variation.(3)'In the study, 3 QTL with high LR values could be consistently detected on chromosomes 1, 2 and 3, respectively. Two of them located on chromosomes 1 and 2 displayed over-dominant effects, and the other QTL mapped on chromosome 3 was additive. The QTL alleles relevant to head smut resistance on chromosomes 1 and 3 were contributed by the parent Mo 17, while the QTL allele on chromosome 2 was contributed by Huangzao4.(4) Most of the QTL relevant to head smut resistance identified in this paper showed additive or over-dominant effects.