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Absence of Os β CA1 causes a CO 2 deficit and affects leaf photosynthesis and the stomatal response to CO 2 in rice
Author(s) -
Chen Taiyu,
Wu Huan,
Wu Jiemin,
Fan Xiaolei,
Li Xianghua,
Lin Yongjun
Publication year - 2017
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1111/tpj.13497
Subject(s) - photosynthesis , botany , chemistry , biology , horticulture
Summary Plants always adjust the opening of stomatal pores to adapt to the environment, for example CO 2 concentration ([CO 2 ]), humidity and temperature. Low [CO 2 ] will trigger the opening of stomatal pores to absorb extra CO 2 . However, little is known about how CO 2 supply affects the carbon fixation and opening of stomatal pores in rice. Here, a chloroplast‐located gene coding for β‐carbonic anhydrase (βCA) was found to be involved in carbon assimilation and the CO 2 ‐mediated stomatal pore response in rice. Os β CA1 was constitutively expressed in all tissues and its transcripts were induced by high [CO 2 ] in leaves. Both T‐DNA mutant and RNA interference lines showed phenotypes of lower biomass and CA activities. Knockout of Os β CA1 obviously decreased photosynthetic capacity, as demonstrated by the increased CO 2 compensation point and decreased light saturation point in the mutant, while knockout increased the opening ratio of stomatal pores and the rate of water loss. Moreover, the mutant showed a delayed response to low [CO 2 ], and stomatal pores could not be closed to the same degree as those of wild type even though the stomatal pores could rapidly respond to high [CO 2 ]. Genome‐wide gene expression analysis via RNA sequencing demonstrated that the transcript abundance of genes related to Rubisco, photosystem compounds and the opening of stomatal pores was globally upregulated in the mutant. Taken together, the inadequate CO 2 supply caused by the absence of Os β CA1 reduces photosynthetic efficiency, triggers the opening of stomatal pores and finally decreases their sensitivity to CO 2 fluctuation.