Abstract
Aquaporin forms water-conducting channel, which facilitates passive water transport across cellular membranes. Among 11 PIP and 10 TIP aquaporins in rice, several members including OsPIP2;3, PIP2;4, PIP2;5 and TIP2;1 are highly root specific. Expression levels of these aquaporins showed diurnal pattern that was low at night and high in daytime. However, up-regulation in the daytime is almost cancelled when the shoots are exposed to over-humid condition, suggesting that transpirational forcing strongly induces aquaporin expression in the roots. To investigate the relation between meteorological conditions and aquaporin abundance, young seedlings grown in a growth chamber for 2 weeks were exposed into open field condition. We found that several aquaporins in the roots showed close correlation with the transpirational forcing (potential evaporation, Ep), which can be calculated from downward short- and long-wave radiation, water pressure deficit, air temperature and wind speed.
