title: Diversity among isolates of cowpea severe mosaic virus  infecting cowpeas in northeastern Brazil.
abstract: Eleven isolates of cowpea severe mosaic virus (CPSMV),  a member of the genus Comovirus, were selected from 50 samples collected  of nine cowpea fields in Northeastern Brazil (Piauí, Ceará, Rio Grande do  Norte, Paraíba, Pernambuco, Alagoas, Sergipe, Bahia, and Distrito Federal) and  partially sequenced. The RNA1 partial sequence, corresponding to the helicase,  viral genome-linked protein, picornain 3C-like protease, and the RNA-directed  RNA polymerase genes from CPSMV, had high identity among isolates, varying from  98 to 100%. No evidence was found for intermolecular or intramolecular  recombination. Phylogenetic analysis confirmed that the Brazilian CPSMV  isolates are substantially different from the CPSMV strain USA. Despite the low  variability found among Brazilian CPSMV isolates, there were notable differences  in the symptomatology of infected cowpea plants, ranging from mild to moderate.  Previous reports have demonstrated an association between CPSMV symptom  determinants and helicase. However, we found no correlation between the  helicase mutations and symptoms caused by CPSMV. Nevertheless,  all isolates with mutation R to K in the protease provoked severe symptoms.  This type of information can provide a foundation for the development of  strategies to produce durable resistant cowpea lines. It is crucial for  strategies based on DNA sequence-dependent technologies, such as inhibition  with RNAi.
authors.affiliation: Embrapa Mandioca e Fruticultura, Cruz das Almas, BA, Brasil.
authors.forename: E F M
authors.initials: EF
authors.lastname: Abreu
authors.forename: M L P
authors.initials: ML
authors.lastname: Tinoco
authors.forename: E C
authors.initials: EC
authors.lastname: Andrade
authors.forename: F J L
authors.initials: FJ
authors.lastname: Aragão
mesh_terms: D001938:Brazil; D017798:Comovirus / Q000235:genetics* / Q000302:isolation & purification*; D016384:Consensus Sequence; D007887:Fabaceae / Q000821:virology*; D014644:Genetic Variation; D005843:Geography; D016013:Likelihood Functions; D010802:Phylogeny; D010935:Plant Diseases / Q000821:virology*