G protein γ subunit qPE9-1 is involved in rice adaptation under elevated CO2 concentration by regulating leaf photosynthesis.

G protein γ subunit qPE9-1 plays multiple roles in rice growth and development. However, the role of qPE9-1 in rice exposed to elevated carbon dioxide concentration (eCO2) is unknown. Here, we investigated its role in the regulation of rice growth under eCO2 conditions using qPE9-1 overexpression (OE) lines, RNAi lines and corresponding WT rice. Compared to atmospheric carbon dioxide concentration (aCO2), relative expression of qPE9-1 in rice leaf was approximately tenfold higher under eCO2. Under eCO2, the growth of WT and qPE9-1-overexpressing rice was significantly higher than under aCO2. Moreover, there was no significant effect of eCO2 on the growth of qPE9-1 RNAi lines. Furthermore, WT and qPE9-1-overexpressing rice showed higher net photosynthetic rate and carbohydrate content under eCO2 than under aCO2. Moreover, the relative expression of some photosynthesis related genes in WT, but not in RNAi3 line, showed significant difference under eCO2 in RNA-seq analysis. Compared to WT and RNAi lines, the rbcL gene expression and Rubisco content of rice leaves in qPE9-1-overexpressors were higher under eCO2. Overall, these results suggest that qPE9-1 is involved in rice adaptation under elevated CO2 concentration by regulating leaf photosynthesis via moderating rice photosynthetic light reaction and Rubisco content.