Characterization ofArabidopsis thalianaGCN2 kinase roles in seed germination and plant development

Abstract

Eukaryotic GCN2 (general control nonderepressible 2) is a serine/threonine protein kinase that plays an essential role in modulating amino acid metabolism in response to nutrient deprivation. A wide spectrum of GCN2 functions in yeast and mammals has been characterized that spans from responses to amino acid deficiency, development, differentiation and proper functions of mammalian organs to organism's life span, tumor cell survival and immune responses. Here we demonstrate that Arabidopsis thaliana GCN2 (AtGCN2) plays crucial roles in plant growth and development. We present evidence that AtGCN2 negatively regulates seed germination under diverse environmental conditions. Our genetic data supported the notion that AtGCN2 is required for leaf morphology and normal cellular physiology by controlling chlorophyll contents. Our gene expression analyses revealed that AtGCN2 negatively regulates several transcription factor genes that play important roles in plant gibberellic acid-related crosstalk. We concluded that AtGCN2 plays pivotal roles in various cellular processes essential for normal growth and development, hence expanding the functions of this general regulator beyond being merely a stress player.

Translation regulation in plants: an interesting past, an exciting present and a promising future

“…If eIF2α is phosphorylated, eIF2 binds too tightly to eIF2B and cannot be regenerated, and thus recycled, in future rounds of translation initiation (Jackson et al ., ). The only kinase known to phosphorylate eIF2α in plants is GENERAL CONTROL NONDEREPRESSIBLE2 (GCN2) (Lageix et al ., ; Zhang et al ., ), which reduces global protein synthesis and plays a crucial role in plant growth and development (Lageix et al ., ; Liu et al ., ); however, no direct evidence for GCN2 regulating the formation of the ternary complex exists in plants (Browning and Bailey‐Serres, ). AtGCN1 interacts with GCN2 to mediate the phosphorylation of eIF2α.…”

Light activates the translational regulatory GCN2 kinase via reactive oxygen species emanating from the chloroplast

“…The eIF2a phosphorylation data, above, support a role for GCN2 under high light. Under normal laboratory conditions, gcn2-1 (Landsberg ecotype) mutants display few, if any, phenotypic abnormalities (Lageix et al, 2008;Zhang et al, 2008;Faus et al, 2015;Liu et al, 2015). After exposure to 3 days of continuous high light, the growth of gcn2-1 mutant seedlings was retarded as compared to wild type, specifically in roots and by overall fresh weight ( Fig.…”

Translational Control in the Latency of Apicomplexan Parasites

“…Instead other effector proteins take their place. For example in Arabidopsis thaliana , the stress-responsive transcription factor TBF1 is translationally regulated by eIF2 phosphorylation and GCN2 plays an important role in seed germination [5,119]. In the protozoan Dictyostelium discoideum , GCN2-mediated eIF2 phosphorylation is required for the production of the bZIP transcription factor BzpR which plays an important role in differentiation [4].…”