A membrane-bound NAC transcription factor NTL8 regulates gibberellic acid-mediated salt signaling in Arabidopsis seed germination
A membrane-bound NAC transcription factor NTL8 regulates gibberellic acid-mediated salt signaling in Arabidopsis seed germination
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DOI：
10.1111/j.1365-313x.2008.03493.x
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发表时间：
2008-07-01
期刊：
影响因子：
7.2
通讯作者：
Park, Chung-Mo
中科院分区：
文献类型：
--
作者：
Kim, Sang-Gyu;Lee, An-Kyo;Park, Chung-Mo
赤霉素（GA）通过与其他生长激素和外界信号的协同作用，在种子萌发过程中起着关键作用。然而，外部信号被纳入GA信号通路的方式在很大程度上是未知的。在这里，我们表明，膜结合的NAC转录因子NTL 8介导的盐调节种子萌发通过GA途径，主要是独立的阿坝。NTL 8是高盐诱导的。其表达也被GA生物合成抑制剂多效唑（PAC）升高，但被GA抑制。值得注意的是，高盐度极大地抑制了GA 3氧化酶1（GA 3 ox 1）基因，支持盐信号通过抑制GA生物合成来抑制种子萌发的假设。ABA缺失突变体aba 3 -1在高盐条件下仍能诱导NTL 8的表达和抑制GA 3 ox 1的表达。因此，T-DNA插入ntl 8 -1突变体种子的萌发对高盐和PAC具有抗性。有趣的是，NTL 8在冷吸胀过程中被显著诱导，但在发芽种子中诱导迅速下降，如RGL 2。NTL 8活性还通过膜结合的NTL 8形式的受控蛋白水解释放来调节。它从膜中的释放被PAC和高盐度激活。我们的数据支持NTL 8调节GA介导的盐信号在调节种子萌发。这种调节机制可能提供了一种适应性适应性，在高盐条件下延迟种子萌发。
Gibberellic acid (GA) plays a key role in seed germination through coordinate interactions with other growth hormones and external signals. However, the way in which external signals are incorporated into the GA-signaling pathway is largely unknown. Here, we demonstrate that a membrane-bound NAC transcription factor NTL8 mediates the salt regulation of seed germination via the GA pathway, primarily independently of ABA. NTL8 is induced by high salinity. Its expression is also elevated by a GA biosynthetic inhibitor paclabutrazol (PAC), but is repressed by GA. Notably, high salinity greatly represses the GA3 oxidase 1 (GA3ox1) gene, supporting the hypothesis that salt signals inhibit seed germination by repressing GA biosynthesis. Induction of NTL8 and repression of GA3ox1 by high salinity still occur in the ABA-deficient aba3-1 mutant. Accordingly, the germination of a T-DNA insertional ntl8-1 mutant seed is resistant to high salinity and PAC. Interestingly, NTL8 is significantly induced during cold imbibition, but the induction declines quickly in germinating seeds, like RGL2. NTL8 activity is also regulated by controlled proteolytic release of the membrane-bound NTL8 form. Its release from the membranes is activated by PAC and high salinity. Our data support that NTL8 modulates GA-mediated salt signaling in regulating seed germination. This regulatory scheme may provide an adaptative fitness, which delays seed germination under high salinity conditions.