Abstract
Cold acclimation process plays a vital role in plants survival to cold temperature stress. To elucidate the cold acclimation process, we analyzed the osmotic root hydraulic conductivity under cold stress for prolonged time and showed that chilling sensitive rice roots respond to the cold stress by a gradual increase in its osmotic hydraulic conductivity. Compared to 25C control plants, low root temperature treatment (LRT) at 10C dramatically reduced the hydraulic conductivity. However it gradually increased during the 5 day treatment and reached 10 fold higher at day 5 compared to the plants whose LRT treatment was just started. The gradual increase of the root hydraulic conductivity was found to be linked with a gradual increase in the expression of root aquaporins, specifically the OsPIP2;5. Further, the contrasting expression pattern of aquaporins under LRT and whole plant chilling techniques suggests that shoot signal is a prerequisite for triggering the root aquaporin signal. Collectively, these results demonstrate that cold acclimation process is also functional in chilling sensitive plants and regulated by inter-cellular signaling of aquaporin expressions.
