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A Common Gene for Resistance to Bean Yellow Mosaic Virus and Watermelon Mosaic Virus 2 in Pisum sativum. W. T. Schroeder, Professor, Department of Plant Pathology, New York State Agricultural Experiment Station, Cornell University, Geneva, New York 14456; R. Provvidenti, Research Associate, Department of Plant Pathology, New York State Agricultural Experiment Station, Cornell University, Geneva, New York 14456. Phytopathology 61:846-848. Accepted for publication 19 February 1971. DOI: 10.1094/Phyto-61-846.

Genetic studies of inheritance of resistance and susceptibility to bean yellow mosaic virus (BYMV) and watermelon mosaic virus 2 (WMV-2) in Pisum sativum with F₁, F₂, and F₃ populations and clones of some F₂ families established that a common gene, mo mo, governed resistance to BYMV and WMV-2. Thirty-two cultivars possessing the mo mo genotype for resistance to BYMV were also completely resistant to WMV-2, and 32 cultivars with the susceptible Mo Mo genotype were also susceptible to WMV-2. Both viruses were readily transmitted by the pea aphid, Acyrthosiphon pisum. In pea, WMV-2 generally incited more severe symptoms than did most strains of BYMV. No cross-protection between viruses was demonstrated in pea. Temperature relations of genotypes to infections by WMV-2 were essentially similar to those of BYMV, especially the breakdown of resistance at high temperatures with production of “thermal” strains.