Identification of quantitative trait loci for Goss's wilt of maize.
Since its discovery in 1969, Goss's wilt, a foliar blight and vascular wilt disease caused by the Gram-positive bacterium Clavibacter michiganensis (Smith) Davis et al. subsp. nebraskensis (Vidaver & Mandel) Davis et al. (Cmn), has emerged as one of the top four diseases of maize (Zea mays L.) in the United States and Ontario, Canada. No source of complete resistance has been described for Goss's wilt, and little is known about the genetic and mechanistic basis of host resistance to Cmn. Our objective was to perform linkage mapping on three populations to uncover the genomic regions associated with Goss's wilt resistance. We evaluated the intermated B73 × Mo17 population and two corresponding disease-resistant introgression line populations: B73(4) × Mo17 and Mo17(4) × B73. We identified putative quantitative trait loci (QTLs) in bins 1.05 to 1.06, 2.06, 7.01 to 7.02, 8.05, and 10.04, both confirming previous findings and identifying novel resistance QTLs. The QTL on chromosome 1, designated qGW1.06, was identified in multiple environments and overlaps with a known multiple disease resistance locus. The QTL in bin 8.05 represents a novel region associated with Goss's wilt. Using the data from this study and previous studies, we found that Goss's wilt resistance was correlated with northern leaf blight [Setosphaeria turcica (Luttr.) K.J. Leonard & Suggs], but not gray leaf spot (Cercospora spp.) or southern leaf blight [Cochliobolus heterostrophus (Drechsler) Drechsler]. These results offer a deeper understanding of the genetic basis of resistance to Goss's wilt in maize that may facilitate breeding for resistance, and qGW1.06 is a strong candidate for further characterization and use.