Suppression of the heterotrimeric G protein causes abnormal morphology, including dwarfism, in rice

Transgenic rice containing an antisense cDNA for the alpha- subunit of rice heterotrimeric G protein produced little or no mRNA for the subunit and exhibited abnormal morphology, including dwarf traits and the setting of small seeds. In normal rice, the mRNA for the a subunit was abundant in the internodes and florets, the tissues closely related to abnormality in the dwarf transformants. The position of the alpha-subunit gene was mapped on rice chromosome 5 by mapping with the restriction fragment length polymorphism. The position was closely linked to the locus of a rice dwarf mutant, Dailioku dwarf (d-1), which is known,vn to exhibit abnormal phenotypes similar to those of the transformants that suppressed the endogenous mRNA for the a subunit by antisense technology. Analysis of the cDNAs for the alpha- subunits of five alleles of Daikoku dwarf (d-1), ID-1, DK22, DKT-1, DKT-2, and CM1361-1, showed that these dwarf mutants had mutated in the coding region of the alpha-subunit gene. These results show that the G protein functions in the formation of normal internodes and seeds in rice.