To rapidly sense and defend against various microbial pathogens infection, plants have developed an effective innate immune system to protect themselves. Members of WRKY proteins function as important regulators of plant disease resistance toward biotrophic pathogens. The WRKY transcription factors function as regulators involved in disease resistance against both biotrophs and necrotrophs. Previous studies have shown that group III members are responsive to salicylic acid (SA) and pathogen infection.

Prof. Yu Diqiu and his research team of Xishuangbanna Tropical Botanical Garden (XTBG) conducted a study to further clarify the functions of Arabidopsis group III WRKY factors in plant defense. They chose WRKY46 for further investigation. Their study showed that Arabidopsis WRKY46 is specifically induced by salicylic acid (SA) and biotrophic pathogen Pseudomonas syringae infection.

To determine its biological functions directly, the researchers have isolated its loss-of-function T-DNA insertion mutants and cultured gain-of-function transgenic WRKY46 over-expressing plants. Since WRKY46 shares similar expression pattern with evolutionarily related WRKY70 and WRKY53 in response to SA and pathogen induction, they also generated double mutants (wrky46wrky70 and wrky46wrky53) and triple mutants (wrky46wrky70wrky53) through genetic crossing, to elucidate possible functional cooperation among them.

Functional analysis of the single, double and triple mutants and 35S:WRKY46 transgenic plants in response to P. syringae infection indicated that pathogen-induced WRKY46 functions partially redundantly with WRKY70 and WRKY53 in plant disease resistance.

The work was supported by the Science Foundation of the Ministry of Agriculture of the People's Republic of China (2009ZX08009-066B).

The study entitled “Arabidopsis WRKY46 coordinates with WRKY70 and WRKY53 in basal resistance against pathogen Pseudomonas syringae” has been published in Plant Science, 185-185: 288-297, doi:10.1016/j.plantsci.2011.12.003.