Elevated CO₂ increases photosynthesis, biomass and productivity, and modifies gene expression in sugarcane
2008
DE SOUZA, AMANDA PEREIRA | GASPAR, MARILIA | DA SILVA, EMERSON ALVES | ULIAN, EUGÊNIO CÉSAR | WACLAWOVSKY, ALESSANDRO JAQUIEL | NISHIYAMA JR., MILTON YUTAKA | DOS SANTOS, RENATO VICENTINI | TEIXEIRA, MARCELO MENOSSI | SOUZA, GLAUCIA MENDES | Buckeridge, Marcos Silveira
Because of the economical relevance of sugarcane and its high potential as a source of biofuel, it is important to understand how this crop will respond to the foreseen increase in atmospheric [CO₂]. The effects of increased [CO₂] on photosynthesis, development and carbohydrate metabolism were studied in sugarcane (Saccharum ssp.). Plants were grown at ambient (~370 ppm) and elevated (~720 ppm) [CO₂] during 50 weeks in open-top chambers. The plants grown under elevated CO₂ showed, at the end of such period, an increase of about 30% in photosynthesis and 17% in height, and accumulated 40% more biomass in comparison with the plants grown at ambient [CO₂]. These plants also had lower stomatal conductance and transpiration rates (-37 and -32%, respectively), and higher water-use efficiency (c.a. 62%). cDNA microarray analyses revealed a differential expression of 35 genes on the leaves (14 repressed and 22 induced) by elevated CO₂. The latter are mainly related to photosynthesis and development. Industrial productivity analysis showed an increase of about 29% in sucrose content. These data suggest that sugarcane crops increase productivity in higher [CO₂], and that this might be related, as previously observed for maize and sorghum, to transient drought stress.
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