A New Tomato-Infecting Begomovirus in Barbados

Area of Science:

• Plant Virology
• Molecular Biology
• Entomology

Background:

• Tomato plants in Barbados displayed severe leaf curling symptoms in 1998, correlated with increased whitefly populations.
• These symptoms suggested a potential viral infection transmitted by whiteflies.

Purpose of the Study:

• To identify and characterize the causal agent of the observed tomato leaf curl symptoms in Barbados.
• To determine if the identified virus is a known geminivirus or a novel species.

Main Methods:

• DNA was extracted from symptomatic tomato leaves for Polymerase Chain Reaction (PCR) analysis using degenerate primers for DNA-A and DNA-B.
• PCR products were sequenced, and DNA sequences were compared to known geminiviruses using BLAST and phylogenetic analysis.
• Dot blot hybridization assays were performed using the amplified DNA-A fragment as a probe to detect the virus in various plant species.

Main Results:

• PCR amplification yielded DNA-A (1.3 kb) and DNA-B (1.4 kb) fragments, indicative of a bipartite begomovirus.
• Sequence analysis revealed the virus shared highest nucleotide identity with Cabbage leaf curl virus (CaLCuV) and Squash leaf curl virus (SqLCV-E), but was distinct enough to be considered a new species.
• The virus, provisionally named Tomato leaf curl Barbados virus (ToLCBBV), was detected in symptomatic tomato plants and showed weak signals in muskmelon and watermelon with similar symptoms.

Conclusions:

• A novel bipartite begomovirus, ToLCBBV, is the causal agent of severe leaf curl in Barbados tomato.
• The virus has a potential to infect other cucurbit species, though at lower titers.
• This finding expands the known diversity of whitefly-transmitted geminiviruses in the Western Hemisphere.