Abstract
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.
Highlights
Atmospheric carbon dioxide concentration has increased at a rate of 2 ppm/year since 2002
We found that the promoter sequence of qPE9-1 had the CCRE3 (TGACGC) element (Table S4)
We determined that G protein γ-subunit qPE9-1 played a positive role in rice growth under elevated CO2 concentration (eCO2) by regulating Anet and Rubisco content in leaves
Summary
Atmospheric carbon dioxide concentration (aCO2) has increased at a rate of 2 ppm/year since 2002. Human population will reach ten billion by 2050 (United Nations 2015), which will lead to overexploitation of natural resources. It will be a big challenge for us to intensify agro-productions to feed this growing. Rice (Oryza sativa L.) is a major staple food crop for almost half of the global population (Kurai et al 2011). Exposure to eCO2, rice yield is improved by increasing plant growth, tiller number and leaf area (Kimball 2016; Hasegawa et al 2013). The gas exchange and net photosynthetic rate increase under eCO2 conditions (Norby et al 2016). Different studies have been employed to evaluate the effect of eCO2 on crops, but the underlying molecular mechanisms and signaling
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