VIEW ARTICLE

Etiology

Two New Serotypes of Cowpea Severe Mosaic Virus. M. T. Lin, Instituto de Ciêcias Biológicas, Universidade de Brasília, 70910 Brasília, DF, Brazil; J. H. Hill(2), E. W. Kitajima(3), and C. L. Costa(4). (2)Department of Plant Pathology, Seed and Weed Sciences, Iowa State University, Ames 50011; (3)(4)Instituto de Ciêcias Biológicas, Universidade de Brasília, 70910 Brasília. Phytopathology 74:581-585. Accepted for publication 30 September 1983. Copyright 1984 The American Phytopathological Society. DOI: 10.1094/Phyto-74-581.

Two cowpea severe mosaic virus isolates, V-1 and one from bean, were identified as new serotypes III and IV, respectively. Serotype III differed from the other serotypes by infecting Nicotiana tabacum ' TNN.' Serotype IV was unable to infect Chenopodium amaranticolor, a known diagnostic host for this virus. Two beetle species, Cerotoma arcuata and Diabrotica speciosa, transmitted serotype IV from beans to beans. Cytological alterations induced in plants infected by these four serotypes were similar, except the fibrous inclusions appeared to be induced less frequently by serotypes III and IV than by the other two. Two major proteins with apparent molecular weights of 40,300- 41,800 daltons (d) and 20,100- 21,400 d were detected in the middle components of the four serotypes. A minor protein of about 22,400- 23,300 d was detected in serotypes I, III, and IV, but not in serotype II. Serological analysis showed that cross reactivity among the four serotypes was due to the common antigenic determinant A. Serotypes I, III, and IV share an additional common determinant designated as B. Serotypes I and IV also have the common determinant designated C. Each serotype also has a specific antigenic determinant D, E, F, and G for serotypes I, II, III, and IV, respectively, which contribute to their serological distinction.