Screening and analysis of genes expressed upon infection of broad bean with Clover yellow vein virus causing lethal necrosis

Clover yellow vein virus (ClYVV) causes lethal systemic necrosis in legumes, including broad bean (Vicia faba) and pea (Pisum sativum). To identify host genes involved in necrotic symptom expression after ClYVV infection, we screened cDNA fragments in which expression was changed in advance of necrotic symptom expression in broad bean (V. faba cv. Wase) using the differential display technique and secondarily with Northern blot analysis. Expression changes were confirmed in 20 genes, and the six that exhibited the most change were analyzed further. These six genes included a gene that encodes a putative nitrate-induced NOI protein (VfNOI), and another was homologous to an Arabidopsis gene that encodes a glycine- and proline-rich protein GPRP (VfGPRP). We recently reported that necrotic symptom development in ClYVV-infected pea is associated with expression of salicylic acid (SA)-dependent pathogenesis-related (PR) proteins and requires SA-dependent host responses. Interestingly, VfNOI and VfGPRP expression was correlated with that of the putative SA-dependent PR proteins in ClYVV-infected broad bean. However, broad bean infected with a recombinant ClYVV expressing the VfGPRP protein showed weaker symptoms and less viral multiplication than that infected with ClYVV expressing the GFP protein. These results imply that VfGPRP plays a role in defense against ClYVV rather than in necrotic symptom expression

A new satellite RNA is associated with natural infections of cucumber mosaic virus in succulent snap bean

Cucumber mosaic virus (CMV) was consistently recovered from symptomatic snap bean plants during surveys conducted in 2007 and 2008 in central Wisconsin. A large proportion of these CMV-infected plants contained a single-stranded linear RNA molecule consisting of 339 nucleotides and sharing 90–94% sequence identity with other satellite (sat) RNAs of CMV. Comparison of this satRNA sequence with currently available CMV satRNA sequences suggests this to be a novel satRNA