Cotton Mi-1.2-like Gene: A potential source of whitefly resistance

Abstract

Whitefly (Bemisia tabaci) inflicts tremendous yield losses to cotton crops in many parts of the world by sap-sucking and transmitting viral diseases. The tomato-associated Mi-1.2 gene has been successfully deployed in tomato cultivars to attain whitefly resistance. In the current study, putative Mi-1.2-like orthologs were identified in five whitefly hosts and functionally validated through virus-inducing gene silencing (VIGS) in cotton plants. The expression profiling and qPCR results depicted differential regulation of the Mi-1.2-like gene in various tissue types and under different biotic and abiotic stresses, especially in whitefly susceptible and resistant cotton plants. The upregulation of the Mi-1.2-like gene (Gadrp RPP-13 Like gene) was observed at 24 h and 48 h post-whitefly exposure (PWFE) in whitefly resistant (FDH-228) and tolerant (Mac7) cotton plants as compared to susceptible plants of Coker-312. However, delayed expression was recorded at 72 h of PWFE in Coker-312 plants. In TRV based gene silencing experiment, silencing of the Mi-1.2-like gene, significantly enhanced the whitefly infestation on both whitefly-resistant and susceptible cotton genotypes. Based on these results, we conducted the evolutionary analysis of Mi-1.2-like orthologs among cotton, cassava, tomato, papaya, and cucumber hosts. This indicated that cotton associated Mi-1.2 like gene has a close relation with cassava and tomato. These results suggested that Mi-1.2-like R genes could be the potential candidate for deriving whitefly resistance response in cotton plants.