Arabidopsis eIF2α kinase GCN2 is essential for growth in stress conditions and is activated by wounding

Background: Phosphorylation of eIF2 alpha 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 eIF2 alpha. 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-1-carboxylic acid (ACC) and salicylic acid, further suggests that this enzyme could play a role in plant defense against insect herbivores.