Seok Hye-Yeon, Woo Dong-Hyuk, Nguyen Linh Vu, Tran Huong T, Tarte Vaishali N, Mehdi Syed Muhammad Muntazir, Lee Sun-Young, Moon Yong-Hwan
Department of Molecular Biology, Pusan National University, Busan, 609-735, South Korea.
Planta. 2017 Feb;245(2):329-341. doi: 10.1007/s00425-016-2609-0. Epub 2016 Oct 21.
AtNAP , an Arabidopsis NAC transcription factor family gene, functions as a negative regulator via transcriptional repression of AREB1 in salt stress response. AtNAP is an NAC family transcription factor in Arabidopsis and is known to be a positive regulator of senescence. However, its exact function and underlying molecular mechanism in stress responses are not well known. Here, we investigated functional roles of AtNAP in salt stress response. AtNAP expression significantly increased at the seedling stage, with higher expression in both shoots and roots under NaCl, mannitol, and ABA treatments. T-DNA insertional loss-of-function mutants of AtNAP were more tolerant to salt stress than wild type (WT), whereas AtNAP-overexpressing transgenic plants (OXs) were more sensitive to salt stress than WT during germination, seedling development, and mature plant stage. Transcript levels of stress-responsive genes in the ABA-dependent pathway, such as AREB1, RD20, and RD29B, were significantly higher and lower in atnap mutants and AtNAP OXs, respectively, than in WT under salt stress conditions, suggesting that AtNAP might negatively regulate the expression of those genes under salt stress conditions. Indeed, AtNAP repressed the promoter activity of AREB1 under normal and salt stress conditions. These results indicate that AtNAP functions as a negative regulator in the salt stress response. Our results, together with previous studies, suggest that AtNAP functions as a negative regulator in osmotic stress responses, whereas it functions as a positive regulator in senescence.
AtNAP是拟南芥NAC转录因子家族基因，在盐胁迫响应中通过转录抑制AREB1发挥负调控作用。AtNAP是拟南芥中的一个NAC家族转录因子，已知是衰老的正调控因子。然而，其在胁迫响应中的具体功能和潜在分子机制尚不清楚。在此，我们研究了AtNAP在盐胁迫响应中的功能作用。AtNAP在幼苗期表达显著增加，在NaCl、甘露醇和ABA处理下，地上部和根部的表达均较高。AtNAP的T-DNA插入功能缺失突变体比野生型（WT）更耐盐胁迫，而在萌发、幼苗发育和成熟植株阶段，过表达AtNAP的转基因植株（OXs）比WT对盐胁迫更敏感。在盐胁迫条件下，ABA依赖途径中胁迫响应基因如AREB1、RD20和RD29B的转录水平在atnap突变体中显著高于WT，在AtNAP OXs中显著低于WT，这表明AtNAP可能在盐胁迫条件下负调控这些基因的表达。事实上，AtNAP在正常和盐胁迫条件下均抑制AREB1的启动子活性。这些结果表明AtNAP在盐胁迫响应中起负调控作用。我们的结果与先前的研究一起表明，AtNAP在渗透胁迫响应中起负调控作用，而在衰老中起正调控作用。
