Abstract
Aquaporins play important roles in plant water transport. According to the former reports, Arabidopsis and maize have more than 30 different aquaporins, however, there have been little previous works on all rice aquaporins. We identified 32 different aquaporin genes from the rice genomic database. According to phylogenetic analysis, they were classified into four major subgroups; 11 plasmamembrane (PIPs), 10 tonoplast (TIPs), nine NOD26-like (NIPs) and two small basic intrinsic proteins (SIPs). Semi-quantitative RT-PCR analysis revealed the differences in expression patterns of each aquaporin gene; some genes were expressed in two or more organs, while others were mostly in one organ. In addition, some aquaporin gene expressions changed during developmental stages and in day/night cycle. Chilling stress decreased most aquaporin gene expressions, however, the variation of decrease was different among aquaporins. Further analysis is in progress to investigate water permeability of each rice aquaporin.
