Heterotrimeric G-protein subunits regulate plant architecture, pod development, seed size, and symbiotic nodulation in Medicago truncatula

This study is led by Professor Jiangli Dong (College of Biological Sciences, China Agricultural University, Beijing, China). The authors focused on the model legume plant Medicago truncatula, and systematically analyzed the functions of two G-protein-encoding genes, MtGα1 and MtGβ1, along with Regulator of G-protein Signaling1 (MtRGS1). The authors generated the first set of stably edited mutants Mtgα1, Mtgβ1, and Mtrgs1 using CRISPR/Cas9 in legumes. The authors investigated the developmental, reproductive, and symbiotic nodulation-related phenotypes of these mutants, expanding the understanding of the biological functions of G proteins in legumes.

The composition of the core canonical G proteins in M. truncatula appears to be relatively simple, with only one Gα and one Gβ genes. MtGα1, MtGβ1, and MtRGS1 were widely expressed in multiple tissues. The subcellular locations of MtGα1 and MtRGS1 at the plasma membrane, and MtGβ1 in the nucleus, cytoplasm, and plasma membrane are consistent with those of canonical G proteins in other plant species. Mtgβ1 mutants displayed an overall smaller plant architecture, including smaller leaflets, shorter plants, fewer branches, shorter root, lower biomass, and smaller pods with shorter spines and smaller, lighter seeds. Mtgα1 mutants displayed curly, round leaflets, and slight dwarfism, and formed smaller pods, yet larger and heavier seeds. The phenotypic consequences of mutations in these three genes on nodulation showed that Mtgβ1 mutants displayed a marked drop in nodule fresh weight, suggesting that MtGβ1 positively regulates nodulation in M. truncatula.

In summary, these phenotypic analysis revealed that MtGα1 and MtGβ1 play important roles in plant growth and development, whereas MtRGS1 contributes to these processes only to a relatively modest degree. The phenotypes of G-protein mutants in M. truncatula display both similarities and differences when compared to those in other plant species, highlighting the inherent complexity of G-protein signaling pathways.

See the article:

Heterotrimeric G-protein subunits regulate plant architecture, pod development, seed size, and symbiotic nodulation in Medicago truncatula

https://link.springer.com/article/10.1007/s42994-025-00210-x