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

Okamoto, Haruko, Gobel, Cornelia, Capper, Richard G., Saunders, Nigel, Feussner, Ivo and Knight, Marc C. (2009) The ?-subunit of the heterotrimeric G-protein affects jasmonate responses in Arabidopsis thaliana. Journal of Experimental Botany, 60 (7). (doi:10.1093/jxb/erp060).

Abstract

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 G? subunit loss-of-function mutation gpa1-1 on the Arabidopsis transcriptome. The analysis indicated that the G? subunit may play a role in response to jasmonic acid (JA). Consistent with this, G? mutants showed a reduced response to JA in inhibition of chlorophyll accumulation and root growth, whilst G? gain-of-function plants overexpressing G? 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 G? loss- and gain-of-function Arabidopsis lines indicated that G? positively modulates the expression of the Vegetative Storage Protein (VSP) gene. This indicates that the G? subunit regulates a subset of JA-regulated genes defining a branch point in this signalling pathway in Arabidopsis. Further analysis of the impact of G? 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 G? mutant. This supports the observation that a significant proportion of, but not all, JA-regulated gene expression is mediated by G?

This record has no associated files available for download.

Contributors

Download statistics