Cloning and Analyzing of G-protein β-Subunit Gene in <I>Rhizoctonia solani</I> Causing Soybean Sharp Eyespot

Targeted disruption of two G-protein α subunit genes in the chestnut blight fungus Cryphonectria parasitica revealed roles for the Giα subunit CPG-1 in fungal reproduction, virulence, and vegetative growth. A second Gα subunit, CPG-2, was found to be dispensable for these functions. We now report the cloning and targeted disruption of a C. parasitica G-protein β subunit gene. The deduced amino acid sequence encoded by this gene, designated cpgb-1, was found to share 66.2, 65.9, and 66.7% amino acid identity with Gβ homologues from human, Drosophila, and Dictyostelium origins, respectively, but only 39.7% identity with the Saccharomyces cerevisiae Gβ homologue STE4 product. Low stringency Southern hybridization failed to detect any related Gβ subunit genes in C. parasitica. Targeted disruption of cpgb-1 resulted in several of the changes previously reported to accompany disruption of the C. parasitica Giα subunit gene cpg-1. These included very significant reductions in pigmentation, asexual sporulation, and virulence. In contrast to results obtained for Giα gene disruption, the reduction in virulence resulting from the disruption of a Gβ gene was accompanied by increased, rather than decreased, vegetative growth on synthetic medium. The relevance of these results to mechanisms of fungal virulence is considered.

Download Full-text

The maize heterotrimeric G protein β subunit controls shoot meristem development and immune responses

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1917577116 ◽

2019 ◽

Vol 117 (3) ◽

pp. 1799-1805 ◽

Cited By ~ 9

Author(s):

Qingyu Wu ◽

Fang Xu ◽

Lei Liu ◽

Si Nian Char ◽

Yezhang Ding ◽

...

Keyword(s):

G Protein ◽

Cross Talk ◽

Normal Growth ◽

Shoot Meristem ◽

Β Subunit ◽

Subunit Gene ◽

Α Subunit ◽

Knock Out ◽

Meristem Size ◽

Meristem Development

Heterotrimeric G proteins are important transducers of receptor signaling, functioning in plants with CLAVATA receptors in controlling shoot meristem size and with pathogen-associated molecular pattern receptors in basal immunity. However, whether specific members of the heterotrimeric complex potentiate cross-talk between development and defense, and the extent to which these functions are conserved across species, have not yet been addressed. Here we used CRISPR/Cas9 to knock out the maize G protein β subunit gene (Gβ) and found that the mutants are lethal, differing from those in Arabidopsis, in which homologous mutants have normal growth and fertility. We show that lethality is caused not by a specific developmental arrest, but by autoimmunity. We used a genetic diversity screen to suppress the lethal Gβ phenotype and also identified a maize Gβ allele with weak autoimmune responses but strong development phenotypes. Using these tools, we show that Gβ controls meristem size in maize, acting epistatically with G protein α subunit gene (Gα), suggesting that Gβ and Gα function in a common signaling complex. Furthermore, we used an association study to show that natural variation in Gβ influences maize kernel row number, an important agronomic trait. Our results demonstrate the dual role of Gβ in immunity and development in a cereal crop and suggest that it functions in cross-talk between these competing signaling networks. Therefore, modification of Gβ has the potential to optimize the trade-off between growth and defense signaling to improve agronomic production.

Download Full-text