Rate D N, Cuenca J V, Bowman G R, Guttman D S, Greenberg J T
Chemistry and Biochemistry Graduate Program, University of Colorado at Boulder, Boulder, Colorado 80309, USA.
Plant Cell. 1999 Sep;11(9):1695-708. doi: 10.1105/tpc.11.9.1695.
We isolated a dominant gain-of-function Arabidopsis mutant, accelerated cell death 6 (acd6), with elevated defenses, patches of dead and enlarged cells, reduced stature, and increased resistance to Pseudomonas syringae. The acd6-conferred phenotypes are suppressed by removing a key signaling molecule, salicylic acid (SA), by using the nahG transgene, which encodes SA hydroxylase. This suppression includes phenotypes that are not induced by application of SA to wild-type plants, indicating that SA acts with a second signal to cause many acd6-conferred phenotypes. acd6-nahG plants show hyperactivation of all acd6-conferred phenotypes after treatment with a synthetic inducer of the SA pathway, benzo(1,2, 3)thiadiazole-7-carbothioic acid (BTH), suggesting that SA acts with and also modulates the levels and/or activity of the second defense signal. acd6 acts partially through a NONEXPRESSOR OF PR 1 (NPR1) gene-independent pathway that activates defenses and confers resistance to P. syringae. Surprisingly, BTH-treated acd6-nahG plants develop many tumor-like abnormal growths, indicating a possible role for SA in modulating cell growth.
我们分离出了一个具有显性功能获得性的拟南芥突变体——加速细胞死亡6（acd6），其防御反应增强，有死亡和增大的细胞斑块，植株矮小，对丁香假单胞菌的抗性增加。通过使用编码水杨酸（SA）羟化酶的nahG转基因去除关键信号分子SA，可抑制acd6赋予的表型。这种抑制包括那些野生型植株施用SA不会诱导产生的表型，这表明SA与第二种信号共同作用导致许多acd6赋予的表型。在用SA途径的合成诱导剂苯并（1,2,3）噻二唑-7-硫代羧酸（BTH）处理后，acd6-nahG植株显示出所有acd6赋予的表型的过度激活，这表明SA与第二种防御信号共同作用，并且还调节其水平和/或活性。acd6部分通过不依赖病程相关蛋白1（PR1）基因的途径发挥作用，该途径激活防御反应并赋予对丁香假单胞菌的抗性。令人惊讶的是，用BTH处理的acd6-nahG植株会出现许多肿瘤样异常生长，这表明SA在调节细胞生长中可能发挥作用。
