The Gossypium hirsutum WRKY gene GhWRKY39- 1 promotes pathogen infection defense responses and mediates salt stress tolerance in transgenic Nicotiana benthamiana.

Key message: Our results indicate that overexpression of the GhWRKY39 - 1 gene enhances resistance to pathogen infection and tolerance to high salt and oxidative stress in transgenic Nicotiana benthamiana. Abstract: WRKY transcription factor genes play significant roles in the response to biotic and abiotic stresses. Cotton ( Gossypium hirsutum) is an important fiber and oil crop worldwide. We isolated and characterized GhWRKY39- 1, which is a group IId WRKY gene that is present as a single copy in the cotton genome. Quantitative PCR analyses indicated that GhWRKY39- 1 was induced by pathogen infection, defense-related signaling molecules, and abiotic stresses, such as NaCl and methyl viologen. An analysis of the subcellular localization of the GhWRKY39-1 protein indicated that it localized to the nucleus. Furthermore, constitutive overexpression of GhWRKY39- 1 in Nicotiana benthamiana conferred a greater resistance to infection by both the bacterial pathogen Ralstonia solanacearum and the fungal pathogen Rhizoctonia solani. The transgenic plants also exhibited elevated mRNA levels of several pathogen-related ( PR) genes, including PR1c, PR2 and PR4. Moreover, transgenic plants displayed an enhanced tolerance to salt and oxidative stress and elevated expression of several oxidation-related genes, including APX, CAT, GST and SOD. Overall, these results indicate that GhWRKY39- 1 functions as a positive regulator of plant defense against pathogen infection and responses to salt stress and reactive oxygen species. [ABSTRACT FROM AUTHOR]