High CO<sub>2</sub>‐ and pathogen‐driven expression of the carbonic anhydrase βCA3 confers basal immunity in tomato
Zhangjian Hu, Qiaomei Ma, Christine H. Foyer, Lei Cui, Hyong Woo Choi, Chenfei Zheng, Jianxin Li, Jinhua Zuo, Zhuo Mao, Yuyang Mei, Jingquan Yu, Daniel F. Klessig, Kai Shi
Abstract
Summary Atmospheric CO 2 concentrations exert a strong influence on the susceptibility of plants to pathogens. However, the mechanisms involved in the CO 2 ‐dependent regulation of pathogen resistance are largely unknown. Here we show that the expression of tomato ( Solanum lycopersicum ) β‐CARBONIC ANHYDRASE 3 ( βCA3 ) is induced by the virulent pathogen Pseudomonas syringae pv. tomato DC3000. The role of βCA3 in the high CO 2 ‐mediated response in tomato and two other Solanaceae crops is distinct from that in Arabidopsis thaliana . Using βCA3 knock‐out and over‐expression plants, we demonstrate that βCA3 plays a positive role in the activation of basal immunity, particularly under high CO 2 . βCA3 is transcriptionally activated by the transcription factor NAC43 and is also post‐translationally regulated by the receptor‐like kinase GRACE1. The βCA3 pathway of basal immunity is independent on stomatal‐ and salicylic‐acid‐dependent regulation. Global transcriptome analysis and cell wall metabolite measurement implicate cell wall metabolism/integrity in βCA3‐mediated basal immunity under both CO 2 conditions. These data not only highlight the importance of βCA3 in plant basal immunity under high CO 2 in a well‐studied susceptible crop–pathogen system, but they also point to new targets for disease management strategies in a changing climate.