Early detection of salt stress is vital for plant survival and growth. Still, the molecular processes controlling early salt stress perception and signaling are not fully understood. Here, we identified SALT-RESPONSIVE ERF1 (SERF1), a rice (Oryza sativa) transcription factor (TF) gene that shows a root-specific induction upon salt and hydrogen peroxide (H2O2) treatment. Loss of SERF1 impairs the salt-inducible expression of genes encoding members of a mitogen-activated protein kinase (MAPK) cascade and salt tolerance–mediating TFs. Furthermore, we show that SERF1-dependent genes are H2O2 responsive and demonstrate that SERF1 binds to the promoters of MAPK KINASE KINASE6 (MAP3K6), MAPK5, DEHYDRATION-RESPONSIVE ELEMENT BINDING2A (DREB2A), and ZINC FINGER PROTEIN179 (ZFP179) in vitro and in vivo. SERF1 also directly induces its own gene expression. In addition, SERF1 is a phosphorylation target of MAPK5, resulting in enhanced transcriptional activity of SERF1 toward its direct target genes. In agreement, plants deficient for SERF1 are more sensitive to salt stress compared with the wild type, while constitutive overexpression of SERF1 improves salinity tolerance. We propose that SERF1 amplifies the reactive oxygen species–activated MAPK cascade signal during the initial phase of salt stress and translates the salt-induced signal into an appropriate expressional response resulting in salt tolerance.
鹽脅迫的早期對于植物的存活和生長至關(guān)重要，然而，控制早期鹽脅迫感知和信號傳導(dǎo)的分子進(jìn)程仍不甚明了。本文鑒定了SALT-RESPONSIVE ERF1 (SERF1)，一個水稻轉(zhuǎn)錄因子基因（DREB亞家族成員），表現(xiàn)為受鹽和雙氧水處理后誘導(dǎo)根特異表達(dá)。SERF1功能缺失減弱絲裂原活化蛋白激酶(MAPK)家族成員和耐鹽相關(guān)轉(zhuǎn)錄因子的鹽誘導(dǎo)表達(dá)。進(jìn)一步，我們發(fā)現(xiàn)SERF1依賴基因?qū)2O2有應(yīng)答，SERF1能夠在體內(nèi)和體外結(jié)合在MAP3K6、MAPK5、DREB2A和ZFP179的啟動子上。SERF1也直接誘導(dǎo)其自身表達(dá)。此外，SERF1是MAPK5的磷酸化靶標(biāo)，磷酸化的SERF1轉(zhuǎn)錄活性增強(qiáng)。與野生型相比，SERF1缺陷植株對鹽脅迫更敏感，而SERF1組成型過量表達(dá)植株耐鹽性增強(qiáng)。這些結(jié)果說明SERF1在鹽脅迫初始應(yīng)答階段放大活性氧激活的MAPK級聯(lián)信號通路，將鹽誘導(dǎo)信號轉(zhuǎn)化為適當(dāng)?shù)谋磉_(dá)應(yīng)答，從而產(chǎn)生鹽耐性。