Abstract
Higher plants have α(Gα), β(Gβ), and γ(Gγ) subunits of the heterotrimeric G proteins as well as animals have. In rice, the deficient mutant of the Gα gene (RGA1), d1 exhibits altered phenotypes such as dwarfism, erect and dark-green leaves and small round seeds. The mutants for the Gβ gene (RGB1) and the Gγ gene (RGG1) were not isolated in rice. In order to estimate the function of Gβ, we produced the transformants that RGB1 expression was suppressed by RNAi in WT and d1-5, and named rgb1RNAi/WT and rgb1RNAi/d1-5. rgb1RNAi/WT and rgb1RNAi/d1-5 showed the abnormal phenotypes, namely dwarf, browning of lamina joint region and node, shorten seed and decreased fertility. In regard to cell proliferation, Gβ and Gα worked independently as a positive regulator. Browning of lamina joint regions and nodes in rgb1RNAi/WT and rgb1RNAi/d1-5 was a novel characteristic, which was not occurred in d1-5. These results indicate that Gβ has some independent functions, compared with Gα in rice.
