CASAR82A, a pathogen-induced pepper SAR8.2, exhibits an antifungal activity and its overexpression enhances disease resistance and stress tolerance

Pepper SAR8.2 gene (CASAR82A) was previously reported to be locally or systemically induced in pepper plants by biotic and abiotic stresses. In this study, the physiological and molecular functions of the pepper SAR8.2 protein in the plant defense responses were investigated by generating Arabidopsis transgenic lines overexpressing the CASAR82A gene. The transgenic Arabidopsis plants grew faster than the wild-type plants, indicating that the CASAR82A gene was involved in plant development. The ectopic expression of CASAR82A in Arabidopsis was accompanied by the expression of the Arabidopsis pathogenesis-related (PR)-genes including AtPR-1, AtPR-4 and AtPR-5. CASAR82A overexpression enhanced the resistance against infections by Pseudomonas syringae pv. tomato, Fusarium oxysporum f.sp. matthiolae or Botrytis cinerea. The transgenic plants also exhibited increased NaCl and drought tolerance during all growth stages. Moreover, the methyl viologen test showed that the transgenic plants were tolerant to oxidative stress. The purified recombinant CASAR82A protein and crude protein extracts of the transgenic plants exhibited antifungal activity against some phytopathogenic fungi, indicating that the enhanced resistance of the transgenic plants to fungal pathogen infection may be due to the antifungal effect of SAR8.2 protein.