Cotton leaf curl virus (CLCuV) is one of the major limiting factors in cotton production systems worldwide. The widely cultivated cotton species, Gossypium hirsutum, is particularly sensitive to attack by this virus. The main symptom of infection is, as the name suggests, curling of the leaves resulting in stunted growth and can reduce flowering, cotton boll formation and yield. Whitefly serves as a viral vector when feeding on the cotton plant. A second species of cotton, Gossypium arboreum, is totally resistant to this viral disease. Whilst whitefly also feed on G. arboreum this species has a natural defence system that does not allow the virus to cause infection and disease. The exact mechanisms conferring disease resistance in cotton are still unknown.
A recent study published in AoBP by Mushtaq et al. employed various approaches to identify possible resistance genes against CLCuV infection and contribute to understanding disease resistance in cotton species. The authors identified some genes of the defence system of G. arboreum that contribute to making this species resistant to leaf curl disease. The same genes were found in G. hirsutum however gene expression was more variable among tested genotypes. Knowledge of the interaction of the identified genes with other cotton pathogens could possibly be utilised to improve the resistance of susceptible G. hirsutum and other plant species.