The cytokinin-activated transcription factor ARR2 promotes plant immunity via TGA3/NPR1-dependent salicylic acid signaling in Arabidopsis
- Dev Cell. 2010 Aug 17;19(2):284-95. doi: 10.1016/j.devcel.2010.07.011.
- 1. Department of Life Sciences, Pohang University of Science and Technology, Korea.
Cytokinins affect plant immunity to various pathogens; however, the mechanisms coupling plant-derived cytokinins to pathogen responses have been elusive. Here, we found that plant-derived cytokinins promote resistance of Arabidopsis to Pseudomonas syringae pv. tomato DC3000 (Pst). Modulated Cytokinin levels or signaling activity in CKX- or IPT-overexpressing Plants or in ahk2 ahk3 mutants correlated with altered resistance. In fact, the cytokinin-activated transcription factor ARR2 contributes specifically to Pst resistance. The salicylic acid (SA) response factor TGA3 binds ARR2, and mutation of TGA-binding cis-elements in the Pr1 promoter abolished cytokinin- and ARR2-dependent Pr1 activation. Cytokinin treatment did not increase pathogen resistance in tga3 Plants, as the cytokinin-dependent induction of Pr1 was eliminated. Moreover, SA signaling enhanced binding of ARR2/TGA3 to the Pr1 promoter. Taken together, these results show that cytokinins modulate the SA signaling to augment resistance against Pst, a process in which the interaction between TGA3 and ARR2 is important.