The carbohydrate metabolism enzymes sucrose-P synthase and ADG-pyrophosphorylase in phaseolus bean leaves are up-regulated at elevated growth carbon dioxide and temperature

Abstract

Kidney bean ( Phaseolus vulgaris L. cv. Montcalm) plants were grown under daytime maximum/nighttime minimum temperatures of 28/18, 34/24 and 40/30 °C at ambient carbon dioxide concentration (CO 2; 350 μmol mol −1), and 28/18, 31/21, 34/24, 37/27 and 40/30 °C at elevated (twice-ambient) CO 2, to characterize how increases in growth CO 2 and temperature affected kidney bean leaf photosynthesis and carbohydrate metabolism. Elevated CO 2 enhanced leaf photosynthetic rates by about 57% across the temperature regimes, compared with plants grown an ambient CO 2. As growth temperature increased from 28/18 to 40/30 °C, leaf photosynthetic rates decreased at both ambient and elevated CO 2. Growth at either elevated temperature or CO 2 decreased activity, protein content and activation of the primary photosynthetic enzyme ribulose 1,5-bisphosphate carboxylase-oxygenase (Rubisco). Elevated CO 2 increased activities of sucrose-phosphate synthase (SPS) and adenosine-5′-diphosphoglucose pyrophosphorylase (AGP) and accumulation of soluble sugars and starch across all temperatures, compared with plants grown at ambient CO 2. At elevated CO 2, growth temperatures above 34/24 °C significantly increased leaf carbohydrates (total soluble sugars and starch) and activity of AGP. The up-regulation of leaf carbohydrate metabolism enzymes under elevated CO 2 plus temperature would be beneficial for growth and productivity of kidney bean in future climates.