Photosynthetic Response and Carboxylation Activity of Enzymes in Leaves and Roots of Water Chestnut, Trapa bispinosa Roxb.

A water chestnut, Trapa bispinosa Roxb., plant often develops a large scale root system in natural waters. The roots are green colored with chlorophyll and capable of photosynthesis using light energy coming through the water. The production of this plant depends solely on the photosynthesis of these roots until leaves expand on and above the water surface to function in photosynthesis. Interestingly photosynthesis in this plant is carried out under two different environments; by roots in water and by leaves in the atmosphere. We investigated photosynthetic features of green roots in terms of O₂ evolution response and activity of photosynthetic enzymes. Leaf photosynthesis exhibited a C3 type trait, but in roots photosynthetic system was comparative to that of the submerged type (SUM) showing an increased activity in phosphoenolpyruvate carboxylase (PEPCase) and malate accumulation in root cells at night.