Abstract:
Objective Roles of heat-shock HSP70 and its interactive protein in regulating blast resistance of rice plants were analyzed. Previously identified OsHSP70-2 and its interacting OsPR10a from rice plants with durable resistance to blast disease were used as a reference.
Methods An OsHSP70-2 mutant was constructed by phylogenetic analysis and gene editing to measure the lesion area and fungal biomass for a phenotypic analysis. Roles and relationship between OsHSP70-2 and OsPR10a was studied using bimolecular fluorescence complementation and luciferase complementary imaging experiments. Cell death induced by the proteins was verified on a tobacco system and by a double luciferase transient expression assay.
Results There were certain species-specific variations in the motif of OsHSP70-2, but a high degree of conservation existed in the overall protein structure. In vitro, the OsHSP70-2 mutant rice plants obtained by gene editing were more sensitive to Magnaporthe oryzae inoculation. An interaction between OsHSP70-2 and OsPR10a was confirmed, and their co-expression, not OsPR10a alone, caused tobacco cell death.
Conclusion OsHSP70-2 might regulate the nuclease activity expression through appropriate folding, stability, or subcellular localization of PR10a to activate the downstream defense response. The preliminarily revealed molecular mechanism by this study indicated that OsHSP70-2 mediated the homeostasis of rice plants through regulating OsPR10a. The information would substantially facilitate the breeding of disease resistant varieties.
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