Biochemical and physiological time-of-day variations in early-development phase of Agave mapisaga and Agave salmiana.

Abstract

This research assesses the aboveground matter accumulation and Fv/Fm ratios (maximum quantum efficiency of PSII) in young plants (5months old) of Agave mapisaga and Agave salmiana grown under greenhouse conditions. This study also evaluated changes in the relative abundance of several different metabolites (sugars, free amino acids, and soluble phenols) during the major daily phases (I, III, and IV) of Crassulacean acid metabolism (CAM). These two species were also investigated to determine if differences in these parameters were evident with respect to their geographical origins (i.e. Metepec, Tlajomulco, and Tlaxiaca, in the state of Hidalgo, Mexico). Differences in shoot mass (0.51-0.82g plant-1 ), water content (75-93%), fructose (4-27μmolg-1 ), glucose (57-73μmolg-1 ), sucrose (10-30μmolg-1 ), free amino acids (5-25μmolg-1 ), soluble phenolics (0.7-3.5μmolg-1 ), and Fv/Fm ratios (0.75-0.80) were evident between plants with different origins. Specifically, at the end of Phase I compared to Phase IV, the results showed significant reductions in dry matter (up to 3.3%) and also reductions in fructose/sucrose. Relative amino acid concentrations were lowest in Phase III (8.8μmolg-1 ) compared to Phase I (16μmolg-1 ). These are novel observations, since all these changes and the biochemical and physiological performance in the CAM phases have not been previously determined in Agave plants differing in their geographical origins.