Characterization of a novel recombinant begomovirus and tomato leaf curl Kunene virus infecting bottle gourd in Kenya

Leaves of bottle gourd (Lagenaria siceraria (Molina) Standl.) exhibiting mottling and interveinal chlorosis symptoms Were collected from Meru, Kenya, in 2023. The current study investigated the causal agent of this disease.

Polymerase Chain Reaction (PCR) using universal begomovirus primers confirmed the presence of a monopartite begomovirus in two out of four symptomatic samples. No satellite DNA or DNA-B components were detected. Full-length genome sequencing and BLAST analysis identified one isolate (L5; GenBank accession no. LC865744) as tomato leaf curl Kunene virus (ToLCKunV) with a nucleotide identity of 91.2%, while the other (L4; LC865743) showed low nucleotide identity (at most 87.4%) to any known begomovirus. Recombination analysis revealed that the novel virus (L4) is a chimera derived from ToLCKunV-[Na:19] and tomato leaf curl Uganda virus [UG:Iga:05]. Based on ICTV criteria, this recombinant qualifies as a new begomovirus species, for which we propose a new species name "Begomovirus lagenariae" and virus name "bottle gourd leaf mottling virus (BGLMV-[KE:Mer:23])". Infectious clones of both isolates were constructed and used to successfully infect Nicotiana benthamiana, tomato, cucumber, and bottle gourd under controlled conditions.

This study presents the first evidence of begomovirus infection in cucurbit crops in Kenya, highlighting the presence of two distinct viral isolates: a newly characterized recombinant, BGLMV, and a local isolate of ToLCKunV.