A new adenylyl cyclase, putative disease-resistance RPP13-like protein 3, participates in abscisic acid-mediated resistance to heat stress in maize
Hao Yang, Yulong Zhao, Ning Chen, Yanpei Liu, Shaoyu Yang, Hanwei Du, Wei Wang, Jianyu Wu, Fuju Tai, Feng Chen, Xiuli Hu
Abstract
In plants, 3´,5´-cyclic adenosine monophosphate (cAMP) is an important second messenger with varied functions; however, only a few adenylyl cyclases (ACs) that synthesize cAMP have been identified. Moreover, the biological roles of ACs/cAMP in response to stress remain largely unclear. In this study, we used quantitative proteomics techniques to identify a maize heat-induced putative disease-resistance RPP13-like protein 3 (ZmRPP13-LK3), which has three conserved catalytic AC centres. The AC activity of ZmRPP13-LK3 was confirmed by in vitro enzyme activity analysis, in vivo RNAi experiments, and functional complementation in the E. coli cyaA mutant. ZmRPP13-LK3 is located in the mitochondria. The results of in vitro and in vivo experiments indicated that ZmRPP13-LK3 interacts with ZmABC2, a possible cAMP exporter. Under heat stress, the concentrations of ZmRPP13-LK3 and cAMP in the ABA-deficient mutant vp5 were significantly less than those in the wild-type, and treatment with ABA and an ABA inhibitor affected ZmRPP13-LK3 expression in the wild-type. Application of 8-Br-cAMP, a cAMP analogue, increased heat-induced expression of heat-shock proteins in wild-type plants and alleviated heat-activated oxidative stress. Taken together, our results indicate that ZmRPP13-LK3, a new AC, can catalyse ATP for the production of cAMP and may be involved in ABA-regulated heat resistance.