Summary auto-generated
Bean yellow dwarf virus (BeYDV), a newly identified geminivirus, causes significant yield losses in French bean crops in South Africa, particularly in the Northern Province and Mpumalanga districts. The virus produces stunting, chlorosis, and leaf curling symptoms in infected plants. Researchers isolated and molecularly characterized BeYDV from symptomatic French bean plants, determining it has a single DNA genome component encoding conserved viral genes typical of subgroup I geminiviruses. Testing confirmed the cloned viral genome was infectious in multiple plant species including French bean, tobacco, and Arabidopsis when introduced via agroinoculation. Phylogenetic analysis revealed BeYDV is most closely related to tobacco yellow dwarf virus (TYDV) from Australia, sharing 65% nucleotide sequence identity, but sufficiently distinct to warrant classification as a separate species. Notably, BeYDV, like TYDV, is a subgroup I geminivirus that infects dicotyledonous plants, which is unusual since most subgroup I members infect monocots. The genome organization includes complementary-sense ORF C3 and a C4C1 fusion protein similar to TYDV but absent in other subgroup I members. These findings suggest that adaptation of subgroup I geminiviruses to dicotyledonous hosts may be more common than previously recognized.
Key findings
- Bean yellow dwarf virus (BeYDV) is a newly characterized subgroup I geminivirus causing severe yield losses (85-92% reduction) in French bean crops in South Africa
- BeYDV is most closely related to tobacco yellow dwarf virus (TYDV) from Australia (65% nucleotide identity) but is genetically distinct enough to be classified as a separate species
- Unlike most subgroup I geminiviruses that infect monocots, BeYDV infects dicotyledonous plants (French bean, tomato, Arabidopsis), suggesting host-range adaptation in subgroup I members is more widespread than previously thought
- BeYDV genome encodes novel complementary-sense ORF C3 and spliced C4C1 fusion protein unique to dicot-infecting subgroup I members
- The virus was successfully transmitted to multiple plant species via agroinoculation and produced characteristic geminate viral particles confirmed by electron microscopy
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Abstract
A South African geminivirus for which we propose the name bean yellow dwarf virus (BeYDV) has been isolated from French bean (Phaseolus vulgaris cv. Bonus) showing stunting, chlorosis and leaf curl symptoms. A full-length cloned copy of the viral genome produced characteristic symptoms of the disease when reintroduced into French bean by agroinoculation, and was systemically infectious in Nicotiana benthamiana, N. tabacum, Lycopersicon esculentum, Datura stramonium and Arabidopsis thaliana. BeYDV resembles subgroup I geminiviruses which infect monocotyledonous plants in having a single DNA component, two non-overlapping virion-sense (V1 and V2) and two overlapping complementary-sense (C1 and C2) coding regions, and an intron within the complementary-sense coding regions that is excised to produce a C1C2 fusion protein. It is most closely related to tobacco yellow dwarf virus from Australia, the only subgroup I geminivirus previously known to infect dicotyledonous plants, although it is sufficiently dissimilar (65% nucleotide sequence identity) to be considered a distinct virus.