Incidence and transmission of Faba bean necrotic yellows virus (FBNYV) in Spain

Abstract

Information on the distribution of Faba bean necrotic yellows virus (FBNYV) in Spain was gathered by sampling different legume crops (faba bean "Muchamiel", forage faba bean, pea and chickpea) in four regions (Murcia, Andalucía, Castilla y León, and Extremadura). The virus was detected by TAS-ELISA in faba bean "Muchamiel" and peas only in the Murcia region. A portion of 272 bp within the C5 component of a FBNYV from Murcia was amplified by IC-PCR and directly sequenced. The Spanish FBNYV was 93.75% identical to two previously sequenced isolates of FBNYV from Syria and Egypt. Periodic samplings of faba bean "Muchamiel" over one growing season (Oct. 1999 to Jan. 2000) in Murcia provided no clear evidence of any spread of the disease either within or beyond the affected fields. Mixed infections of FBNYV and Tomato spotted wilt virus (TSWV), Bean leaf roll virus (BLRV) and Bean yellow mosaic virus (BYMV) were commonly observed. The necrotic symptoms developed on the leaf borders were more pronounced in these mixed infections. Transmission experiments using a Spanish isolate as inoculum source and the aphid species Acyrthosiphon pisum and Aphis craccivora showed that both are efficient FBNYV vectors. In these experiments, the faba bean cvs. "Aguadulce", "Muchamiel" and "Valenciana"were all susceptible to FBNYV.