NAC domain transcription factor ATAF1 interacts with SNF1-related kinases and silencing of its subfamily causes severe developmental defects in Arabidopsis

ATAF1, a member of the plant-specific NAC transcription factor family in Arabidopsis thaliana, was identified in two-hybrid and in vitro binding assays as interacting partner of SNF1-related protein kinase (SnRK1) catalytic subunits. SnRK1s represent essential factors in stress and glucose signal transduction, and are involved in coordinate regulation of metabolic, hormonal and developmental signaling pathways. Transcription profiles of ATAF1 and closely related NACs indicate that their expression is coregulated in various organs and by wounding, methyljasmonate, hydrogen peroxide, pathogen infection, abscisic acid, cold, drought, salt and osmotic stress. Transgenic Arabidopsis carrying a 35S::ATAF1 construct developed fast senescing curly leaves and showed various grades of dwarfism leading to growth arrest and subsequent seedling death. RT-PCR analysis exhibited a silencing effect of the overexpression construct that down-regulated transcription of endogenous ATAF family members in plants showing severe developmental defects. These results together with the analysis of T-DNA insertion mutants suggest that the ATAF subfamily members perform redundant functions and act as positive regulators of plant development. (C) 2009 Elsevier Ireland Ltd. All rights reserved.