VIEW ARTICLE

Genetics

Cowpea Stunt: Inheritance Pattern of the Necrotic Synergistic Reaction. G. Pio -Ribeiro, Department of Plant Pathology and Plant Genetics, University of Georgia, Athens 30602, Present address of senior author: Departamento de Agronomia, Universidade Federal Rural de Pernambuco, Dois Irmãos, 50000 Recife PE., Brazil; C. W. Kuhn(2), and B. B. Brantley(3). (2)(3)Department of Horticulture, The Georgia Station, Experiment 30212. Phytopathology 70:250-252. Accepted for publication 4 September 1979. Copyright 1980 The American Phytopathological Society. DOI: 10.1094/Phyto-70-250.

Cowpea cultivars California Blackeye, Clay, and Iron reacted to an inoculum mixture of cucumber mosaic virus and a Georgia isolate of blackeye cowpea mosaic virus (BlCMV) with severe stunt and necrosis (SSN), severe stunt (SS), and mild mottle, respectively. The F₁ plants of the crosses California Blackeye × Clay, California Blackeye × Iron, and Iron × California Blackeye reacted with severe stunt and intermediate necrosis (SSIN), and F₁ plants of Clay × Iron had an SS reaction. In F₂ populations, the disease reactions segregated in a ratio of 1:2:1 (SSN:SSIN:SS). Thus, the necrotic reaction is controlled by an allele, at a single locus, which exhibits incomplete dominance. This assumption was confirmed by the data from backcrosses and F₃ populations. The resistance of Iron to BlCMV and cowpea stunt was not detected in any plants in the F₁, F₂, F₃, or backcross populations.