Abstract
Ability of plants to regulate the hydraulic conductivity inside the plant is crucial for sound growth and survival under adverse environment. In this manuscript, we demonstrated that low-root-temperature induces a decline in root hydraulic conductivity (Lp_r), which causes severe reduction in leaf water potential, stomatal conductance and hence transpiration in rice seedlings. In order to examine hydraulic regulation of rice plants at molecular levels, we identified 33 aquaporins in the genome sequences and characterized them by organ specific localization, water transport activity and stress responsibility of gene expression. We suggest that the low-root-temperature dependent decline in Lp_r, which is observed for several hours, is caused by the inactivation of aquaporins rather than by decrease in their abundances. We also showed that expressions of several root aquaporins are up-regulated during the subsequent acclimation process under low-root-temperature.
