ABSTRACT
ABSTRACT A strain of Bean common mosaic necrosis virus (BCMNV) from Idaho was identified by enzyme-linked immunosorbent assay using monoclonal antibodies and determined to be similar to the NL-3 D strain (of Drifjhout) by reaction of differential bean cultivars. However, this BCMNV strain (designated NL-3 K) caused earlier and more severe symptoms on bean plants representing host groups 0, 4, and 5. The nucleotide sequence encoding the predicted polyprotein of NL-3 K was 9,893 nucleotides (nt) in length, yielding a peptide with a molecular size of 362.1 kDa compared with a 9,626-nt, 350.9-kDa polyprotein for NL-3 D. Sequence analysis of the putative P1 protein suggests that the NL-3 K strain is a recombinant between NL-3 D and the Russian strain (RU1) of Bean common mosaic virus. The P1 protein of NL-3 K consisted of 415 amino acids compared with 317 for NL-3 D. The first 114 predicted amino acids of the NL-3 K P1 region were 98% identical with RU1. The remaining 301 amino acids of the protein shared only 34% identity with RU1 but were 98% identical with NL-3 D. Primers were designed that flanked the recombination point in the P1 coding sequence of NL-3 K. An amplicon of the expected size was produced by reverse-transcriptase polymerase chain reaction of total nucleic acid extracts of bean plants inoculated with NL-3 K, but not from those with NL-3 D or RU1. The increased symptom severity on selected common bean lines induced by NL-3 K suggests that the P1 gene may play a significant role in pathogenicity and virulence.
ABSTRACT
During the 1999 to 2001 growing seasons, symptoms consisting of mosaic, stunting, yellowing, wilting, shortening of internodes, and phloem discoloration were observed in chickpea (Cicer arietinum) grown in the Department of Chuquisaca in southern Bolivia. In some fields, approximately 10% of the plants exhibited viruslike symptoms and suffered greatly reduced seed yields. Lentil (Lens culinaris) was also observed to be infected but not pea (Pisum sativum) or faba bean (Vicia faba) growing in nearby fields. Infected chickpea tissue reacted positively to the potyvirus group-specific monoclonal antibody (MAb), but there was no serological reaction with antisera to the potyviruses Bean yellow mosaic virus, Clover yellow vein virus, Cowpea aphid-borne mosaic virus, Pea seedborne mosaic virus, Bean common mosaic virus, or Bean common mosaic necrosis virus. Western blots of total protein extracts probed with the potyvirus MAb revealed a single band ca. 32 kDa. Comparative sequence analysis of cDNA clones generated from the putative coat protein gene consisted of 282 amino acids (31.9 kDa) and showed moderate identities of 67, 66, 63, 63, and 61% with the coat proteins of potyviruses Pepper severe mosaic virus, Pepper yellow mosaic virus, Potato virus Y, Plum pox virus, and Pepper mottle virus, respectively. Phylogenetic analysis of the coat protein amino acid sequence revealed that this virus is a unique member of the family Potyviridae and is phylogenetically most closely related to a group of Solanaceae-infecting potyviruses rather than to other legumeinfecting potyviruses. The proposed name for the new causal agent is Chickpea yellow mosaic virus.
