Map-based cloning of a recessive gene v₁ for virescent leaf expression in cotton (Gossypium spp.)

Background: Virescence, as a recognizable phenotype in the early development stage of cotton, is not only available for research on chloroplast development and photosynthesis but also for heterosis exploitation in cotton. Methods: In current study, for fine mapping of virescent-1 (v₁) in cotton, three populations with a total of 5 678 individuals were constructed using T582 which has the virescent trait. Tobacco rattle virus, TRV1 and TRV2 (pYL156), were used as vectors for the virus-induced gene silencing (VIGS) assay. Results: The v₁ gene was fine-mapped to a 20 kb interval on chromosome 20 of tetraploid cotton. We identified only one candidate gene with four single nucleotide polymorphisms between parents, among which the single nucleotide polymorphism at the position of 1 082 base pair caused the change of amino acid residue from Arg (3–79) to Lys (T582). The relative expression of the candidate gene in virescent plants was extensively lower than that in normal plants. Nullification of the gene by VIGS significantly turned the green leaf of normal cotton plants into yellow. We named this candidate gene as GhRVL. Conclusions: This study will facilitate the further research on virescent formation, and will be useful for breeding of hybrid cottons.