Abstract
Plant heterotrimeric G proteins have been shown to regulate the size of various organs. There are three types of Gγ subunits in plants: type A, consisting of a canonical Gγ domain; type B, possessing a plant-specific domain at the N-terminus of the Gγ domain; and type C, possessing a plant-specific domain at the C-terminal of the Gγ domain. There is one type A, one type B, and three type C of the five γ-subunits in the rice genome. In type C Gγ subunits, GS3, which controls grain size; DEP1, which controls plant height and panicle branching; and their homolog OsGGC2, which affects grain size, have been reported; however, the function of each gene, their interactions, and molecular mechanisms for the control of plant height have not yet been clarified. In this study, we generated loss-of-function mutants of DEP1 and OsGGC2, which have high homology and similar expression, and investigated their phenotypes. Since both dep1 and osggc2 mutants were dwarfed and the double mutants showed a synergistic phenotype, we concluded that both DEP1 and OsGGC2 are positive regulators of plant height and that their functions are redundant.
Highlights
Heterotrimeric G proteins consist of three subunits (Gα, Gβ, and Gγ) in mammals and yeast cells
The panicle length of dep1 and osggc2 was not significantly different from that of the wild type (WT) (Figure 2c,f), and the grain length was slightly shorter only in dep1 (Figure 2d,g). These results indicate that DEP1 and OsGGC2 are positive regulators of plant height, and DEP1 is a positive regulator of grain length
On the basis of these results, we conclude that DEP1 and OsGGC2 act redundantly to regulate plant height through a Gα-mediated pathway and through another pathway, and that DEP1 regulates grain length through the Gα-mediated pathway, but OsGGC2 does not
Summary
Heterotrimeric G proteins consist of three subunits (Gα, Gβ, and Gγ) in mammals and yeast cells. They act as signal transducers by transferring extracellular information to intracellular components [1,2,3,4]. External signals bind or affect G protein-coupled receptors (GPCRs) to activate them. Activated GPCRs, which function as intrinsic GDP/GTP exchange factors, convert Gα-GDP to Gα-GTP. When GTP binds to the α-subunit (Gα-GTP), heterotrimeric G proteins dissociate into Gα-GTP and Gβγ dimer. Gα-GTP and the Gβγ dimer can regulate the respective effector molecules.
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