MOLECULAR CHARACTERIZATION OF A SUBGROUP-I GEMINIVIRUS FROM A LEGUME IN SOUTH-AFRICA

A South African geminivirus for which we propose the name bean yellow dwarf virus (BeYDV) has been isolated from French bean (Phaseolus vulg aris cv, Bonus) showing stunting, chlorosis and leaf curl symptoms, A full-length cloned copy of the viral genome produced characteristic sy mptoms of the disease when reintroduced into French bean by agroinocul ation, and was systemically infectious in Nicotiana benthamiana, N. ta bacum, Lycopersicon esculentum, Datura stramonium and Arabidopsis thal iana. BeYDV resembles subgroup I geminiviruses which infect monocotyle donous plants in having a single DNA component, two non-overlapping vi rion-sense (V1 and V2) and two overlapping complementary-sense (C1 and C2) coding regions, and an intron within the complementary-sense codi ng regions that is excised to produce a C1C2 fusion protein, It is mos t closely related to tobacco yellow dwarf virus from Australia, the on ly subgroup I geminivirus previously known to infect dicotyledonous pl ants, although it is sufficiently dissimilar (65% nucleotide sequence identity) to be considered a distinct virus.