Post doctoral fellow donald danforth plant science cen saint louis, Missouri
Body of Abstract: The global atmospheric [CO2] had been increased by 50% since the onset of industrial revolution and is likely to rise in the future. As plants are the primary producers for all living beings, a thorough understanding of their developmental and physiological responses to elevated [CO2] is critical to improve productivity. Here we describe our recently discovered role of the heterotrimeric G-proteins in modulating the plants’ responses to elevated [CO2]. Specifically, the developmental and physiological responses of the loss-of-function mutant of Arabidopsis G-protein β subunit AGB1 (agb1 mutant) were significantly diminished to elevated [CO2] compared to the wild type plants . The agb1 mutants exhibited reduced [CO2] dependent increase in rosette size compared to wild type plants when grown at elevated [CO2] of 1000 ppm. However, the mutants performed inherently better at the ambient [CO2] conditions, compared to the WT plants. They had a higher net carbon assimilation rate at the ambient [CO2] of 400 ppm, almost similar to the level of the wild type plants grown at elevated [CO2]. Importantly, even though the agb1 rosette sizes were small, they were heavier, due to the higher carbon assimilation. At the physiological level, the higher carbon assimilation rate of agb1 mutant was corroborated by its inherently higher chlorophyll index, PSII photosynthetic efficiency and electron transport rate. In addition, agb1 mutant had higher transpiration rate than the wild type plants at ambient [CO2], which was reduced at the elevated [CO2], leading to its improved water use efficiency. The already better physiological performances of agb1 under ambient [CO2] caused a diminished response to elevated [CO2] suggesting they had already attained a threshold in photosynthetic efficiency and carbon assimilation which could not be increased further under elevated [CO2]. Taken together, our data suggested AGB1 could be a potential target for plant.