Abstract
Guard cells contain chloroplasts, and the stomata through which exchange of gas takes place. They control the stomatal pore, which serves as a channel for exchange of gas by balancing between CO2 uptake for photosynthesis and water loss through transpiration. As a result, chloroplasts in the guard cells have become potential tool for manipulation toward improvement of plant productivity through photosynthesis. The role of the guard cells chloroplasts can, therefore, be elucidated through manipulations of enzymes for photosynthesis by using molecular means. The cytochrome b6f complex catalyzes the transfer of electrons between the two photosynthetic reaction centers, Photosystems II and Photosystem I, while at the same time, transferring protons across the thylakoid used to synthesize ATP for the Calvin cycle. In this study, the overexpression of the Rieske FeS protein in Arabidopsis exhibited phenotypes, which resulted in substantial improvements of quantum efficiency of PSII. Transgenic lines were significantly higher in early development of the plants. Phenotypes observed in the transformed plants also showed faster initial growth rates evidenced by larger leaf area and faster rosette increases, which may suggest that Rieske might be of importance for enhanced plant growth. The result obtained proves more opportunities await the exploitation of guard cells chloroplasts metabolism toward the improvement of plants.