National Key Laboratory of Crop Genetic Improvement, National Center of Plant Gene Research , Huazhong Agricultural University, Wuhan 430070, China.
Plant Physiol. 2013 Dec;163(4):1868-82. doi: 10.1104/pp.113.226019. Epub 2013 Oct 15.
Plants use a complex signal transduction network to regulate their adaptation to the ever-changing environment. Rice (Oryza sativa) WRKY13 plays a vital role in the cross talk between abiotic and biotic stress signaling pathways by suppressing abiotic stress resistance and activating disease resistance. However, it is not clear how WRKY13 directly regulates this cross talk. Here, we show that WRKY13 is a transcriptional repressor. During the rice responses to drought stress and bacterial infection, WRKY13 selectively bound to certain site- and sequence-specific cis-elements on the promoters of SNAC1 (for STRESS RESPONSIVE NO APICAL MERISTEM, ARABIDOPSIS TRANSCRIPTION ACTIVATION FACTOR1/2, CUP-SHAPED COTYLEDON), the overexpression of which increases drought resistance, and WRKY45-1, the knockout of which increases both bacterial disease and drought resistance. WRKY13 also bound to two cis-elements of its native promoter to autoregulate the balance of its gene expression in different physiological activities. WRKY13 was induced in leaf vascular tissue, where bacteria proliferate, during infection, and in guard cells, where the transcriptional factor SNAC1 enhances drought resistance, during both bacterial infection and drought stress. These results suggest that WRKY13 regulates the antagonistic cross talk between drought and disease resistance pathways by directly suppressing SNAC1 and WRKY45-1 and autoregulating its own expression via site- and sequence-specific cis-elements on the promoters of these genes in vascular tissue where bacteria proliferate and guard cells where the transcriptional factor SNAC1 mediates drought resistance by promoting stomatal closure.
植物利用复杂的信号转导网络来调节其对不断变化的环境的适应。水稻（Oryza sativa）WRKY13 通过抑制非生物胁迫抗性和激活抗病性，在非生物和生物胁迫信号通路的串扰中起着至关重要的作用。然而，WRKY13 如何直接调节这种串扰尚不清楚。在这里，我们表明 WRKY13 是一种转录抑制剂。在水稻对干旱胁迫和细菌感染的反应过程中，WRKY13 选择性地结合到 SNAC1（STRESS RESPONSIVE NO APICAL MERISTEM，ARABIDOPSIS TRANSCRIPTION ACTIVATION FACTOR1/2，CUP-SHAPED COTYLEDON）启动子上的某些特定的顺式元件和序列特异性顺式元件上，过表达 SNAC1 可提高抗旱性，而敲除 WRKY45-1 则可提高细菌病和抗旱性。WRKY13 还结合到其天然启动子的两个顺式元件上，以自动调节其在不同生理活动中的基因表达平衡。在感染过程中，WRKY13 在叶片维管束组织中被诱导，在那里细菌增殖，在保卫细胞中，转录因子 SNAC1 增强了抗旱性，在细菌感染和干旱胁迫期间也是如此。这些结果表明，WRKY13 通过直接抑制 SNAC1 和 WRKY45-1 以及通过其自身基因启动子上的顺式元件的特异性顺式元件来调节自身的表达，从而调节干旱和抗病性途径之间的拮抗串扰，这些顺式元件位于细菌增殖的维管束组织和保卫细胞中，转录因子 SNAC1 通过促进气孔关闭来介导抗旱性。
