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The alpha-subunit of the heterotrimeric G-protein affects jasmonate responses in Arabidopsis thaliana.

Okamoto, H. and Gobel, C. and Capper, R.G. and Saunders, N. and Feussner, I. and Knight, M.R. (2009) 'The alpha-subunit of the heterotrimeric G-protein affects jasmonate responses in Arabidopsis thaliana.', Journal of experimental botany., 60 (7). pp. 1991-2003.


Heterotrimeric G-proteins have been implicated in having a role in many plant signalling pathways. To understand further the role of G-proteins, a preliminary experiment was performed to assess the impact of the Gα subunit loss-of-function mutation gpa1-1 on the Arabidopsis transcriptome. The analysis indicated that the Gα subunit may play a role in response to jasmonic acid (JA). Consistent with this, Gα mutants showed a reduced response to JA in inhibition of chlorophyll accumulation and root growth, whilst Gα gain-of-function plants overexpressing Gα showed the opposite phenotype. The levels of JA and related compounds were unaffected in the gpa1-1 mutant, as was autoregulation of the Allene Oxide Synthase (AOS) gene that encodes a key enzyme for JA biosynthesis. In contrast, further analyses using Gα loss- and gain-of-function Arabidopsis lines indicated that Gα positively modulates the expression of the Vegetative Storage Protein (VSP) gene. This indicates that the Gα subunit regulates a subset of JA-regulated genes defining a branch point in this signalling pathway in Arabidopsis. Further analysis of the impact of Gα loss of function upon the JA-regulated transcriptome using Arabidopsis full genome arrays indicated that up to 29% of genes that are >2-fold regulated by JA in the wild type are misregulated in the Gα mutant. This supports the observation that a significant proportion of, but not all, JA-regulated gene expression is mediated by Gα.

Item Type:Article
Keywords:AOS, Arabidopsis, Heterotrimeric G-protein, G-protein alpha-subunit (GPA1), Jasmonic acid, PDF1.2, VSP, Abscisic-acid, Methyl jasmonate, Beta-subunit, Transcription factor, Cell-proliferation, Disease resistance, Seed-germination, Coupled receptor.
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Publisher statement:This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License ( which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
Record Created:06 Jun 2012 10:20
Last Modified:08 Jun 2012 11:58

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