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Sci. STKE, 21 December 2004
Vol. 2004, Issue 264, p. re20
[DOI: 10.1126/stke.2642004re20]


Plant G Proteins, Phytohormones, and Plasticity: Three Questions and a Speculation

Sarah M. Assmann*

Biology Department, Pennsylvania State University, 208 Mueller Laboratory, University Park, PA 16802–5301, USA.

Abstract: Heterotrimeric guanine nucleotide-binding proteins (G proteins) composed of Gα, Gβ, and G{gamma} subunits are important transducers of hormonal signals in organisms as evolutionarily distant as plants and humans. The genomes of diploid angiosperms, such as that of the model species Arabidopsis thaliana, encode only single canonical Gα and Gβ subunits, only two identified G{gamma} subunits, and just one regulator of G protein signaling (RGS) protein. However, a wide range of processes—including seed germination, shoot and root growth, and stomatal regulation—are altered in Arabidopsis and rice plants with mutations in G protein components. Such mutants exhibit altered responsiveness to a number of plant hormones, including gibberellins, brassinosteroids, abscisic acid, and auxin. This review describes possible mechanisms by which such pleiotropic effects are generated and considers possible explanations for why G protein component mutations in plants fail to be lethal. A possible role of G protein signaling in the control of phenotypic plasticity, a hallmark of plant growth, is also discussed.

*Corresponding author. E-mail: sma3{at}

Citation: S. M. Assmann, Plant G Proteins, Phytohormones, and Plasticity: Three Questions and a Speculation. Sci. STKE 2004, re20 (2004).

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