Heterotrimeric G Protein Signaling in Plant Systems

Heterotrimeric G proteins in plants comprise a guanine nucleotide‐binding α-subunit (Gα) and a tightly associated βγ dimer that resides at the plasma membrane. Unlike their animal counterparts, plant Gα subunits can spontaneously exchange GDP for GTP and thus self-activate in the absence of classical seven-transmembrane G protein-coupled receptors. Signal specificity is achieved through a regulatory module in which ligand-activated receptor-like kinases (RLKs) phosphorylate a seven-transmembrane Regulator of G protein Signalling (RGS) protein. Phosphorylation of RGS1 induces its dissociation from the G protein complex, relieving the Gα subunit from GTPase acceleration. Activated Gα and released Gβγ then interact with distinct effectors to control innate immune responses, hormone signalling, ion channel regulation, stomatal dynamics, sugar sensing and growth responses to abiotic stresses. Variations in G protein subunits influence organ size, yield potential and stress tolerance in crops, underscoring their significance for sustainable agriculture and food security.

Research from Nature Portfolio

Recent studies have elucidated how brassinosteroid receptor kinases integrate sugar signals with heterotrimeric G protein activation. The receptors BRI1 and BAK1 form glucose-dependent complexes with Gα, Gβ and Gγ subunits. Biochemical analyses reveal that BRI1 phosphorylates the Gβγ dimer while BAK1 targets the Gγ subunit, modulating G protein activity in response to external glucose. Genetic experiments in Arabidopsis demonstrate that this receptor–G protein module operates in a common pathway to regulate cell expansion, gene expression and developmental timing, thereby linking energy availability to hormone-mediated growth control.

Heterotrimeric G Protein Signaling in Plant Systems publication trend

The graph below shows the total number of articles in heterotrimeric g protein signaling in plant systems across all publications each year (not limited to Nature Index journals).

Technical terms

Heterotrimeric G protein: A membrane-associated complex of Gα, Gβ and Gγ subunits that cycles between active (GTP-bound) and inactive (GDP-bound) states.

Gα subunit: The guanine nucleotide-binding component that undergoes conformational change upon GTP binding, transmitting the activation signal.

Gβγ dimer: The β and γ subunits that remain together and regulate downstream effectors once released from Gα.

Regulator of G protein Signalling (RGS): A GTPase-accelerating protein that promotes GTP hydrolysis on Gα, returning the heterotrimer to its inactive form.

Receptor-like kinases (RLKs): Single-transmembrane receptors with extracellular ligand-binding domains that initiate intracellular phosphorylation cascades.

References

1. Heterotrimeric G protein signalling in the plant kingdom. Open Biology (2013).
2. G Protein Activation without a GEF in the Plant Kingdom. PLOS Genetics (2012).
3. Ligand-triggered de-repression of Arabidopsis heterotrimeric G proteins coupled to immune receptor kinases. Cell Research (2018).
4. Mutation of RGG2, which encodes a type B heterotrimeric G protein γ subunit, increases grain size and yield production in rice. Plant Biotechnology Journal (2018).
5. BRI1 and BAK1 interact with G proteins and regulate sugar-responsive growth and development in Arabidopsis. Nature Communications (2018).