No 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.

A phytoplasma disease, `stolbur', affects pepper (Capsicum annuum) in Spain. Affected plants have short internodes, green flowers buds and other symptoms that are characteristic of phytoplasma‐induced diseases. Herein the detection and classification of the phytoplasma that may cause the disease is reported. DNA amplification by polymerase chain reaction, sequencing and phylogenetic analysis indicate that this phytoplasma should be classified in the clover proliferation group 16SrVI, a group that is clearly distinct from the stolbur group 16SrXII.

Faba bean is one of the most widely grown protein-producing food legumes. Faba bean plants showing symptoms of shoe stringed leaves, phyllody and flower abortion were observed in fields of Antequera (Málaga, Southern Spain). The etiology of this disease was investigated using graft transmission to periwinkle plants, polymerase chain reaction (PCR) with phytoplasma-specific primers, sequencing and phylogenetic analysis. We could not obtain amplification products from asymptomatic plants, whereas all tests were positive for phytoplasma infection from plants showing symptoms. Phylogenetic analysis indicated that this phytoplasma clustered in the 16SrIII group, the type member of which is X-disease phytoplasma. This is the first report of a phytoplasma infecting faba bean in Spain, and the first report of a phytoplasma in this group infecting faba bean.

The detection of luteoviruses by reverse transcription polymerase chain reaction (RT-PCR) depends on the adequate quality and quantity of extracted viral nucleic acids. We have optimized the detection of Bean leaf roll virus (BLRV) using selective precipitation by LiCl of viral RNA from a small quantity of infected plant tissues and insect vectors. The optimal template for PCR was 15 ll of RT reaction mixture. BLRV was detected in different plant hosts and aphid vectors and Aphis fabae, previously considered to be a non-vector of BLRV, was found to acquire the virus from infected plants.