Barley chitinase genes expression revamp resistance against whitefly (Bemisia Tabaci) in transgenic cotton (Gossypium hirsutum L.)

Background Chitinase is an enzyme that hydrolyzes chitin, a major component of the exoskeleton of insects, including plant pests like whiteflies. The present study aimed to investigate the expression of chemically synthesized barley ch1 and chi2 genes in cotton (Gossypium hirsutum) through Agrobacterium-mediated transformation. Fifty-five putative transgenic cotton plants were obtained, out of which fifteen plants successfully survived and were shifted to the field. Using gene-specific primers, amplification of 447 bp and 401 bp fragments confirmed the presence of the ch1 and chi2 genes in five transgenic cotton plants of the T-0 generation. These five plants were further evaluated for their mRNA expression levels. The T-0 transgenic cotton plants with the highest mRNA expression level and better yield performance in field, were selected to raise their subsequent progenies. Results The T-1 cotton plants showed the highest mRNA expression levels of 3.5-fold in P10 (2) for the ch1 gene and 3.7-fold in P2 (1) for the chi2 gene. Fluorescent in situ hybridization (FISH) confirmed a single copy number of ch1 and chi2 (hemizygous) on chromosome no. 6. Furthermore, the efficacy of transgenes on whitefly was evaluated through an insect bioassay, where after 96 h of infestation, mortality rates of whitefly were calculated to be 78%-80% in transgenic cotton plants. The number of eggs on transgenic cotton plants were calculated to be 0.1%-0.12 per plant compared with the non-transgenic plants where egg number was calculated to be 0.90-1.00 per plant. Conclusion Based on these findings, it can be concluded that the chemically synthesized barley chitinase genes (ch1 and chi2) have the potential to be effective against insects with chitin exoskeletons, including whiteflies. The transgenic cotton plants expressing these genes showed increased resistance to whiteflies, resulting in reduced egg numbers and higher mortality rates.