Background: Phosphorylation of eIF2α provides a key mechanism for down-regulating protein synthesis in response to nutrient starvation or stresses in mammalian and yeast cells. However, this process has not been well characterized in plants Results: We show here that in response to amino acid and purine starvations, UV, cold shock and wounding, the Arabidopsis GCN2 kinase (AtGCN2) is activated and phosphorylates eIF2α. We show that AtGCN2 is essential for plant growth in stress situations and that its activity results in a strong reduction in global protein synthesis. Conclusion: Our results suggest that a general amino acid control response is conserved between yeast and plants but that the plant enzyme evolved to fulfill a more general function as an upstream sensor and regulator of diverse stress-response pathways. The activation of AtGCN2 following wounding or exposure to methyl jasmonate, the ethylene precursor 1-Aminocyclopropane-1carboxylic acid (ACC) and salicylic acid, further suggests that this enzyme could play a role in plant defense against insect herbivores. Background Phosphorylation of the α subunit of eukaryotic translation initiation factor 2 (eIF2α) provides a key mechanism for down-regulating protein synthesis in response to nutrient starvation or stresses [1,2]. Vertebrates use four different eIF2α-kinases (PKR, PERK, HRI and GCN2) to respond to various stresses, and typically one kinase has a predominant role in response to a specific cellular stress condition. For example, in mammals, GCN2 is the primary eIF2α-kinase in response to nutrient limitation , PERK modulates gene expression in response to protein misfolding in the endoplasmic reticulum (ER) , PKR participates in an antiviral pathway mediated by interferon , and HRI couples protein synthesis (predomiPublished: 24 December 2008 BMC Plant Biology 2008, 8:134 doi:10.1186/1471-2229-8-134 Received: 8 September 2008 Accepted: 24 December 2008 This article is available from: http://www.biomedcentral.com/1471-2229/8/134 © 2008 Lageix et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.