Mapping Quantitative Trait Loci for Resistance to Gossa€?s Bacterial Wilt and Leaf Blight in North American Maize by Joint Linkage Analysis

摘要

Gossa€?s wilt and leaf blight is a bacterial disease of maize (Zea mays L.) caused by the Gram-positive bacterium Clavibacter michiganensis subsp. nebraskensis. Gossa€?s wilt has re-emerged as an important disease in the western United States and is spreading to other areas. Although the reasons for this re-emergence are not completely known, it is important to understand the genetic basis of resistance to Gossa€?s wilt. The objective of this study was to map the quantitative trait loci (QTL) underlying resistance to Gossa€?s wilt. To achieve this objective, joint linkage and linkage mapping in 3 of the 25 nested association mapping families were used. Three biparental linkage mapping families including a€?B73a€? ?— a€?Oh43a€?, B73 ?— a€?HP301a€?, and B73 ?— a€?P39a€? were evaluated for Gossa€?s wilt in Nebraska. Eleven QTL were detected on chromosomes 1, 2, 3, 4, 5, and 10 through joint linkage mapping. The joint linkage model explained 45% of the phenotypic variation for Gossa€?s wilt. Linkage mapping in each of the three families identified nine, six, and four QTL in the families B73 ?— Oh43, B73 ?— HP301, and B73 ?— P39, respectively. Joint linkage and linkage analysis were also conducted within each environment to detect any environment-specific QTL. However, most of the QTL were colocalized with QTL detected in across environment joint linkage and linkage mapping. These results will help us to understand the genetic basis of resistance to Gossa€?s wilt better and may facilitate maize breeding programs to incorporate resistance to Gossa€?s wilt into the maize germplasm.