G proteins regulate rice grain size by modulating the Hippo signaling pathway

Area of Science:

• Plant Biology
• Molecular Genetics
• Signaling Pathways

Background:

• G-protein pathways are crucial for plant development, with Gγ proteins like DEP1 and GS3 influencing rice grain size.
• The precise molecular mechanisms linking G proteins to grain size regulation remain incompletely understood.

Purpose of the Study:

• To elucidate the mechanism by which G proteins regulate rice grain size.
• To investigate the role of Gγ proteins in the Hippo signaling pathway.

Main Methods:

• Investigated the interaction between Gγ proteins (DEP1, GS3) and the Hippo pathway component OsSIK1.
• Analyzed the effect of OsSIK1 and OsMOB1A on rice grain size through gene disruption and overexpression.
• Assessed OsMOB1A stability in various mutant and overexpression lines.

Main Results:

• G proteins modulate the stability of OsMOB1A, a core Hippo pathway component.
• OsSIK1 phosphorylates OsMOB1A, regulating its stability and consequently grain size.
• DEP1 and GS3 interact with OsSIK1, altering OsMOB1A phosphorylation and stability in a dose-dependent manner.
• Gγ proteins function upstream of the Hippo pathway in regulating grain size.

Conclusions:

• G proteins regulate rice grain size by modulating the Hippo signaling pathway via OsMOB1A stability.
• This study reveals a novel molecular mechanism for G protein-mediated plant development.
• Identified potential targets (Gγ proteins, OsSIK1, OsMOB1A) for enhancing rice yield.