(200-30) Genetic determinants of photosynthetic efficiency in an Andean and a Mesoamerican accession of Phaseolus vulgaris L. in varying light intensities.
Graduate Research Assistant University of Florida Gainesville, Florida
Body of Abstract: Plant photosynthetic efficiency depends on the quality and quantity of the structural components of the system. Thus, genetic variation that affects these components can alter the efficiency of this biological process. However, the role that genetic variation of anatomical, biochemical, and physiological characters play in the control of gas exchange parameters has not been fully characterized, limiting our ability to manipulate the system. We have characterized the contrasting photosynthetic responses to varying levels of light in Jamapa and Calima, two common bean genotypes from the Mesoamerican and Andean gene pools, respectively. We measured their gas exchange responses to a range of PPFDs (0 to 2000 µmol m-2 s-1). Calima registered higher net assimilation rates than Jamapa at low PPFDs, but the opposite was observed at high PPFDs. These results suggest contrasting adaptive responses to light. Jamapa’s electron transport chain responded to light changes faster than Calima. The maximum rate of Rubisco carboxylase activity (Vcmax) at saturating PPFDs was higher in Jamapa. It is likely that the cell size differences between Calima (large) and Jamapa (small) condition them to respond differently to varying light intensities. Genetic analysis of anatomical, physiological, and biochemical features could help us establish the functional relevance of these characteristics on photosynthetic efficiency under different environments.