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 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. Gene expression studies indicated 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.
