CaMAPK1 Plays a Vital Role in the Regulation of Resistance to Infection and Tolerance to Heat Stress.

As an important member of mitogen-activated protein kinase (MAPK) cascades, MAPKs play an important role in plant defense response against biotic and abiotic stresses; however, the involvement of the majority of the MAPK family members against and heat stress (HS) remains poorly understood. In the present study, CaMAPK1 was identified from the genome of pepper and its function against and HS was analyzed. The transcript accumulations of and the activities of its native promoter were both significantly induced by inoculation, HS, and the application of exogenous hormones, including SA, MeJA, and ABA. Transient expression of showed that CaMAPK1 can be targeted throughout the whole cells in and triggered chlorosis and hypersensitive response-like cell death in pepper leaves, accompanied by the accumulation of HO, and the up-regulations of hormones- and HO-associated marker genes. The knock-down of enhanced the susceptibility to partially by down-regulating the expression of hormones- and HO-related genes and impairing the thermotolerance of pepper probably by attenuating and transcripts. Taken together, our results revealed that CaMAPK1 is regulated by SA, JA, and ABA signaling and coordinates responses to infection and HS in pepper.