Physiological changes in stomata and regulation of genes involved in CAM metabolism in polyploid Agave L.

Abstract In recent years there has been growing interest in increasing plant water use efficiency (WUE) through the introduction of crassulacean acid metabolism (CAM) into C3 crops. However, this task has been hampered because the scaling of CAM to other C3 plants requires knowledge of the enzymatic and regulatory pathways underpinning this temporal CO₂ pump. Agave presents CAM metabolism, to date research aimed at knowing the physiological and morphological adaptations related to CAM metabolism, only includes a small group of species analyzed. With the aim of knowing basic aspects related to the physiological response of polyploid (2n=2x=60 to 2n=6x=180) Agave accessions, we carried out genetic and physiological studies in A. tequilana Weber, A. fourcroydes Lem., and A. angustifolia Haw. Using AFLP markers, differences in genetic variability between the polyploid accessions and their diploid counterparts were found. Analysis of expression by real-time PCR showed that the regulation of CAM in Agave is accompanied by the transcription of RbcL, PEPC and PEPCK. Monitoring of the stomatal opening during the night showed differences according to the level of ploidy of the accessions. The genetic and physiological data obtained suggest that agave species present adaptations and flexibility in the transcriptional regulation of genes related to CAM metabolism, suggesting that some polyploid accessions of Agave L. could be more tolerant to drought and heat, adapting their CO2 exchange mechanisms according to the metabolic needs of each species of agave.