Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/29/2004
Publication Date: 8/1/2004
Citation: Carson, M.L., Stuber, C.W., Senior, M.L. Quantitative trait lociconditioning resistance to phaeosphaeria leaf spot of maize caused by phaeosphaeria maydis. Plant Disease. 89:986-988. Interpretive Summary: Phaeosphaeria leaf spot is a potentially important disease of corn that has recently appeared in the continental United States. Many commercially important parent inbred lines used in producing hybrid seed are particularly susceptible to the disease. There is almost no information available on resistance to the disease. We found that at least five genes on three different corn chromosomes controlled resistance to Phaeosphaeria leaf spot. Our data will aid corn breeders seeking to improve the level of resistance of hybrids to this disease. It will also be useful to other scientists seeking to clone and characterize these genes for disease resistance in corn.
Technical Abstract: Phaeosphaeria leaf spot is a potentially important maize disease that has recently appeared in the continental United States in winter breeding nurseries in southern Florida. Inbred lines related to B73 are particularly susceptible to Phaeosphaeria leaf spot, whereas inbreds related to Mo17 are highly resistant. A previous study of the inheritance of resistance to Phaeosphaeria leaf spot in the cross B73 x Mo17 found that resistance is highly heritable and controlled by the mostly additive gene of three or four loci. In this study, we used 158 recombinant inbred (RI) lines derived from the cross B73 x Mo17 to map quantitative trait loci (QTL) governing resistance. The lines along with the parent inbred lines and F1 were evaluated for PLS resistance in replicated trials over two winter growing seasons in southern Florida. Using the composite interval mapping (CIM) function of PLABQTL software, five QTL on three different chromosomes were found to control PLS resistance in Mo17. In addition, the additive x additive interaction between two of these QTL was found to be significant. Our results are in close agreement with the previous study where generation mean analysis was used.