ATAF2, a NAC Transcription Factor, Binds to the Promoter and Regulates NIT2 Gene Expression Involved in Auxin Biosynthesis

Abstract

The transcription factor ATAF2, one of the plant specific NAC family genes, is known as repressor of pathogenesisrelated genes and responsive to the diverse defense-related hormones, pathogen infection, and wounding stress. Furthermore, it is important to consider that tryptophandependant IAA biosynthesis pathway can be activated by wounding and pathogen. We found that ATAF2pro::GUS reporter was induced upon indole-3-acetonitrile (IAN) treatments. And ataf2 mutant showed reduced sensitivity to IAN whereas 35S::ATAF2 plants showed hyper-sensitivity to IAN. IAN biosynthesis required nitrilase involved in the conversion of IAN to an auxin, indole-3-acetic acid (IAA). We found that the NIT2 gene was repressed in ataf2 knockout plants. Expression of both ATAF2 and NIT2 genes was induced by IAN treatment. Transgenic plants overexpressing ATAF2 showed up-regulated NIT2 expression. ATAF2 activated promoter of the NIT2 gene in Arabidopsis protoplasts. Electrophoretic mobility shift assay revealed that NIT2 promoter region from position -117 to -82 contains an ATAF2 binding site where an imperfect palindrome sequence was critical to the protein-DNA interaction. These findings indicate that ATAF2 regulates NIT2 gene expression via NIT2 promoter binding.

ATAF2 integrates Arabidopsis brassinosteroid inactivation and seedling photomorphogenesis

“…consensus sequence (Wang and Culver, 2012) and a 36 bp A/T-rich sequence (Huh et al, 2012). Here, we have shown that ATAF2 also binds the A/T-rich EE/CBS elements (Fig.…”

“…7C,D), which at least partially explains why ATAF2 loss-and gain-of-function and Col-0 seedlings have no significant difference in hypocotyl length under high fluence rates of light. ATAF2 has been reported to activate the expression of the auxin biosynthesis gene NIT2 (Huh et al, 2012). Thus, both BRs and auxins could be involved in the photomorphogenic phenotypes of ATAF2 mutants.…”

“…ATAF2 suppresses the expression of BAS1 and SOB7 ATAF2 can either activate (Wang et al, 2009;Huh et al, 2012) or suppress (Delessert et al, 2005) the expression of downstream target genes. To test the effects of ATAF2 on BAS1 and SOB7 expression, the transcript accumulation of BAS1 and SOB7 in ATAF2 gain-and loss-of-function seedlings was examined by qRT-PCR (unless otherwise stated, 4-day-old seedlings grown at 25°C were used for all total RNA extraction and hypocotyl measurement experiments).…”

“…Because ATAF2 has been reported to regulate the expression of the auxin biosynthesis gene NIT2 (Huh et al, 2012), the involvement of auxin in ATAF2-mediated seedling phenotypes was tested, along with that of BRs. In contrast to the distinct hypocotyl growth phenotypes in ATAF2 mutants caused by BL and BRZ, treatment with either auxin indole-3-acetic acid (IAA) or the auxin transport inhibitor naphthylphthalamic acid (NPA) (Ruegger et al, 1997) did not significantly affect the hypocotyl growth phenotypes of ATAF2 loss-and gain-of-function seedlings in darkness (Fig.…”

A Lipid-Anchored NAC Transcription Factor Is Translocated into the Nucleus and Activates Glyoxalase I Expression during Drought Stress

“…It has been reported that the CAAATNNNATTTG or [GC] AAA sequence was the specific NAC binding site of ATAF subfamily (Huh et al, 2012;Wang and Culver, 2012). An electrophoretic mobility shift assay (EMSA) confirmed the binding of MfNACsa to the MtGlyI promoter that contained the cis-element (CAAATNNNCTTTG) in vitro.…”