Overexpression of tomato WHIRLY protein enhances tolerance to drought stress and resistance to Pseudomonas solanacearum in transgenic tobacco

Abstract

WHIRLY transcription factors play critical roles in responses to biotic and abiotic stresses, but their other biological functions remain unclear. In this study, SlWHY2, a member of the WHIRLY family, was isolated from Solanum lycopersicum. The role of SlWHY2 was studied using transgenic tobacco plants. Real-time quantitative polymerase chain reaction analysis showed that SlWHY2 expression was induced by polyethylene glycol, NaCl, salicylic acid, hydrogen peroxide, and bacterial pathogens. SlWHY2 overexpression in tobacco caused enhanced tolerance to drought stress, as indicated by lower accumulation of malondialdehyde and relative electrolyte leakage, as well as higher relative water content and activities of superoxide dismutase and ascorbate peroxidase. Moreover, higher expression of cytochrome oxidase 1 (NtCOX1) and open reading frame 1 (NtORF1) were observed under drought in the transgenic lines. This suggested that overexpression of SlWHY2 enhanced tolerance to drought stress by regulating the transcription of mitochondrial genes and stabilizing mitochondrial function. Transgenic tobacco also displayed greater resistance to Pseudomonas solanacearum infection as evidenced by lower reactive oxygen species content and higher expression of defence-related genes. Overall, these findings suggest that SlWHY2 acts as a positive regulator in response to biotic and abiotic stresses.