A G-protein pathway determines grain size in rice

Area of Science:

• Plant Biology
• Genetics
• Agricultural Science

Background:

• Manipulating cereal grain size is crucial for enhancing crop yields.
• Heterotrimeric G proteins play vital roles in plant growth and development.

Purpose of the Study:

• To identify the specific G protein subunits involved in regulating rice grain length.
• To understand the molecular mechanisms by which G proteins influence grain size.

Main Methods:

• Identification of a five-subunit heterotrimeric G protein pathway in rice.
• Analysis of the antagonistic roles of Gα, Gβ, and Gγ subunits (DEP1, GGC2, GS3) in grain size regulation.

Main Results:

• The Gβ protein is essential for rice survival and growth.
• Gα subunit supports grain size expansion.
• Gγ subunits DEP1 and GGC2 increase grain length, while GS3 reduces it through competitive interaction with Gβ.
• Combinations of G-protein variants achieved up to 35% reduction or 19% increase in grain length, impacting grain weight by -40% to +28%.

Conclusions:

• A conserved G protein system regulates grain size in rice.
• This pathway offers a predictable approach for manipulating grain and organ sizes in angiosperms, with implications for crop improvement.