ABSTRACT
In the hexaploid wheat genome, there are three Gα genes, three Gß and twelve Gγ genes, but the function of Gß in wheat has not been explored. In this study, we obtained the overexpression of TaGB1 Arabidopsis plants through inflorescence infection, and the overexpression of wheat lines was obtained by gene bombardment. The results showed that under drought and NaCl treatment, the survival rate of Arabidopsis seedlings' overexpression of TaGB1-B was higher than that of the wild type, while the survival rate of the related mutant agb1-2 was lower than that of the wild type. The survival rate of wheat seedlings with TaGB1-B overexpression was higher than that of the control. In addition, under drought and salt stress, the levels of superoxide dismutase (SOD) and proline (Pro) in the wheat overexpression of TaGB1-B were higher than that of the control, and the concentration of malondialdehyde (MDA) was lower than that of the control. This indicates that TaGB1-B could improve the drought resistance and salt tolerance of Arabidopsis and wheat by scavenging active oxygen. Overall, this work provides a theoretical basis for wheat G-protein ß-subunits in a further study, and new genetic resources for the cultivation of drought-tolerant and salt-tolerant wheat varieties.
Subject(s)
Arabidopsis Proteins , Arabidopsis , GTP-Binding Protein beta Subunits , Arabidopsis/genetics , Arabidopsis/metabolism , Plants, Genetically Modified/genetics , Triticum/genetics , Triticum/metabolism , Droughts , Stress, Physiological/genetics , Seedlings/genetics , Seedlings/metabolism , GTP-Binding Proteins/genetics , Gene Expression Regulation, Plant , Plant Proteins/genetics , Plant Proteins/metabolism , Arabidopsis Proteins/genetics , GTP-Binding Protein beta Subunits/geneticsABSTRACT
Plants being sessile integrate information from a variety of endogenous and external cues simultaneously to optimize growth and development. This necessitates the signaling networks in plants to be highly dynamic and flexible. One such network involves heterotrimeric G-proteins comprised of Gα, Gß, and Gγ subunits, which influence many aspects of growth, development, and stress response pathways. In plants such as Arabidopsis, a relatively simple repertoire of G-proteins comprised of one canonical and three extra-large Gα, one Gß and three Gγ subunits exists. Because the Gß and Gγ proteins form obligate dimers, the phenotypes of plants lacking the sole Gß or all Gγ genes are similar, as expected. However, Gα proteins can exist either as monomers or in a complex with Gßγ, and the details of combinatorial genetic and physiological interactions of different Gα proteins with the sole Gß remain unexplored. To evaluate such flexible, signal-dependent interactions and their contribution toward eliciting a specific response, we have generated Arabidopsis mutants lacking specific combinations of Gα and Gß genes, performed extensive phenotypic analysis, and evaluated the results in the context of subunit usage and interaction specificity. Our data show that multiple mechanistic modes, and in some cases complex epistatic relationships, exist depending on the signal-dependent interactions between the Gα and Gß proteins. This suggests that, despite their limited numbers, the inherent flexibility of plant G-protein networks provides for the adaptability needed to survive under continuously changing environments.
Subject(s)
Arabidopsis/physiology , Heterotrimeric GTP-Binding Proteins/metabolism , Signal Transduction , Stress, Physiological , Arabidopsis/genetics , Arabidopsis Proteins/genetics , Arabidopsis Proteins/metabolism , Epistasis, Genetic , GTP-Binding Protein alpha Subunits/genetics , GTP-Binding Protein alpha Subunits/metabolism , GTP-Binding Protein beta Subunits/genetics , GTP-Binding Protein beta Subunits/metabolism , GTP-Binding Protein gamma Subunits/genetics , GTP-Binding Protein gamma Subunits/metabolism , Gene Regulatory Networks , Heterotrimeric GTP-Binding Proteins/genetics , Loss of Function Mutation , Mutation , Phenotype , Plants, Genetically Modified , Species SpecificityABSTRACT
Cryptochromes are blue light photoreceptors that mediate various light responses in plants and mammals. The heterotrimeric G-protein is known to regulate various physiological processes in plants and mammals. In Arabidopsis, cryptochrome 1 (CRY1) and the G-protein ß subunit AGB1 act antagonistically to regulate stomatal development. The molecular mechanism by which CRY1 and AGB1 regulate this process remains unknown. Here, we show that Arabidopsis CRY1 acts partially through AGB1, and AGB1 acts through SPEECHLESS (SPCH), a master transcription factor that drives stomatal initiation and proliferation, to regulate stomatal development. We demonstrate that AGB1 physically interacts with SPCH to block the bHLH DNA-binding domain of SPCH and inhibit its DNA-binding activity. Moreover, we demonstrate that photoexcited CRY1 represses the interaction of AGB1 with SPCH to release AGB1 inhibition of SPCH DNA-binding activity, leading to the expression of SPCH-target genes promoting stomatal development. Taken together, our results suggest that the mechanism by which CRY1 promotes stomatal development involves positive regulation of the DNA-binding activity of SPCH mediated by CRY1 inhibition of the AGB1-SPCH interaction. We propose that the antagonistic regulation of SPCH DNA-binding activity by CRY1 and AGB1 may allow plants to balance light and G-protein signaling and optimize stomatal density and pattern.