Calcium-binding protein OsANN1 regulates rice blast disease resistance by inactivating jasmonic acid signaling

Abstract

Rice blast, caused by the fungal pathogen Magnaporthe oryzae, is one of the most devastating diseases in rice (Oryza sativa L.). Plant annexins are calcium- and lipid-binding proteins that have multiple functions; however, the biological roles of annexins in plant disease resistance remain unknown. Here, we report a rice annexin gene, OsANN1 (Rice annexin 1), that was induced by M. oryzae infection and negatively regulated blast disease resistance in rice. By yeast two-hybrid screening, we found that OsANN1 interacted with a cytochrome P450 monooxygenase, HAN1 (“HAN” termed “chilling” in Chinese), which has been reported to catalyze the conversion of biologically active jasmonoyl-L-isoleucine (JA-Ile) to the inactive form 12-hydroxy-JA-Ile (12OH-JA-Ile). Pathogen inoculation assays revealed that HAN1 was also a negative regulator in rice blast resistance. Genetic evidence showed that OsANN1 acts upstream of HAN1. OsANN1 stabilizes HAN1 in planta, resulting in the inactivation of the endogenous biologically active JA-Ile. Taken together, our study unravels a mechanism where an OsANN1-HAN1 module impairs blast disease resistance via inactivating biologically active JA-Ile and JA signaling in rice.

Rice OsANN9 Enhances Drought Tolerance through Modulating ROS Scavenging Systems

“…Annexins belong to a multifunctional protein family that exists in plants, animals and fungi [10]. Recent evidence has shown that plant annexins play critical roles in regulating abiotic and biotic stresses [19,21,25,38]. Our previous study showed that OsANN3 enhances tolerance to drought stress by modulating ABAdependent stress response pathways in rice [26].…”

“…Under normal conditions, OsANN1 interacts with OsHAN1 and promotes JA-Ile to exhibit an inactive form. Upon pathogen infection, OsANN1 and HAN1 are separated, leading to HAN1 degradation and JA-Ile accumulation, thus promoting disease resistance [25]. The overexpression of OsANN3 significantly increases drought tolerance by regulating ABA-dependent stress response pathways [26].…”