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Genetics

Identification of a Gene for Resistance to Wheat Streak Mosaic Virus in Maize. Michael D. McMullen, United States Department of Agriculture, Agricultural Research Service (USDA-ARS) and the Department of Agronomy, Ohio Agricultural Research and Development Center-The Ohio State University (OSU-OARDC), Wooster 44691; Raymond Louie, USDA-ARS and the Department of Plant Pathology, Ohio Agricultural Research and Development Center-The Ohio State University (OSU-OARDC), Wooster 44691. Phytopathology 81:624-627. Accepted for publication 7 January 1991. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 1991. DOI: 10.1094/Phyto-81-624.

Wheat streak mosaic virus (WSMV) induces generalized mosaic symptoms in selected maize inbreds. During 1988 and 1989, WSMV was detected in many lines in our maize nursery. WSMV symptoms were associated with the expression of the polymitotic (po) marker in a B73 genetic background. The polymitotic locus is on the short arm of maize chromosome 6. An isolate of WSMV (WSMV-W) from naturally infected plants was used to rub-inoculate greenhouse-grown maize plants segregating (po/po or po/+)B73, and the symptom responses of these plants confirmed the presence of a gene linked to po that controlled resistance to WSMV. Restriction fragment length polymorphism (RFLP) analysis located this gene on either the short arm of chromosome 6 or on the long arm proximal to the RFLP marker locus UMC59. The symptom responses to inoculation with WSMV were also determined for F₂ and backcross plants from crosses between the WSMV-resistant inbred Pa405 and the WSMV-susceptible inbred Oh28. The segregation ratios suggested the presence of multiple genes for resistance to WSMV in Pa405. RFLP analysis of plants from these crosses demonstrated that one gene for resistance in Pa405 was also located on chromosome 6.