RuBisCO activase alleviates adverse effects of Nilaparvata lugens feeding on photosynthesis in Oryza sativa

Brown planthopper (Nilaparvata lugens Stal. Homoptera, Delphacidae) is a pest of rice (Oryza sativa L. Cyperales, Poaceae), whose feeding significantly reduced photosynthesis. Ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO) activase (RCA) is a key photosynthetic enzyme. The aim of this study was to examine whether RCA gene of O. sativa (OsRCA) affects photosynthetic efficiency and thereby growth performance of rice infested by brown planthoppers. For this, we conducted experiments in which we overexpressed OsRCA large and small isoforms (oeRCA_L and oeRCA_S, respectively) and silenced OsRCA (irRCA) in rice. After infestation by brown planthoppers, the photosynthetic rate, plant height and dry weight of overexpressed OsRCA lines were significantly higher than those of wild-type (WT) and irRCA. Initial RuBisCO activity in oeRCA_L and oeRCA_S was also higher than in WT and irRCA. Overexpression OsRCA alleviated the adverse response of the decrease in the chlorophyll content, maximum photochemical efficiency (Fv/Fm) and photochemical performance index (PI_ABS). The increase in energy dissipation and quantum yield of energy dissipation in oeRCA_L and oeRCA_S after infestation by brown planthoppers werer much lower than in WT and irRCA. Thus, we concluded that overexpression of OsRCA, particularly OsRCA_S, can alleviate chlorophyll degradation and reduce heat dissipation of photosystem, thereby reducing the degree of photosynthesis damage caused by brown planthoppers infestation.