Repression by an auxin/indole acetic acid protein connects auxin signaling with heat shock factor-mediated seed longevity
Repression by an auxin/indole acetic acid protein connects auxin signaling with heat shock factor-mediated seed longevity
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DOI：
10.1073/pnas.1014856107
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发表时间：
2010-12-14
影响因子：
11.1
通讯作者：
Jordano, Juan
中科院分区：
文献类型：
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作者：
Carranco, Raul;Manuel Espinosa, Jose;Jordano, Juan
植物激素生长素通过调节生长素/吲哚乙酸（Aux/IAA）蛋白的稳定性来调节生长和发育，生长素/IAA蛋白反过来抑制生长素应答因子（ARF）转录调节因子。在未成熟向日葵胚中进行的瞬时测定中，我们观察到Aux/IAA蛋白HaIAA 27抑制热休克转录因子HaHSFA 9（HSF）的转录激活。我们还发现HaIAA 27在未成熟的向日葵胚中是稳定的，其中我们可以显示天然形式的HaIAA 27和HaHSFA 9之间的双分子荧光互补相互作用。HaIAA 27的生长素抗性形式在转基因烟草种子中过表达，导致与直系同源物HSFA 9基因的下调一致的效果，而天然HaIAA 27形式没有观察到这种效果。因此，HaIAA 27对HSF的抑制可能通过成熟种子中的生长素来减轻。我们发现，HSFs如HaHSFA 9是Aux/IAA蛋白阻遏的靶点。由于HaHSFA 9控制着一个涉及种子寿命和胚胎脱水耐受性的遗传程序，我们的研究结果表明，这些过程可以通过生长素调节的机制。Aux/IAA介导的抑制涉及与ARF不同的转录因子。这一发现拓宽了对生长素反应的解释。
The plant hormone auxin regulates growth and development by modulating the stability of auxin/indole acetic acid (Aux/IAA) proteins, which in turn repress auxin response factors (ARFs) transcriptional regulators. In transient assays performed in immature sunflower embryos, we observed that the Aux/IAA protein HaIAA27 represses transcriptional activation by HaHSFA9, a heat shock transcription factor (HSF). We also found that HaIAA27 is stabilized in immature sunflower embryos, where we could show bimolecular fluorescence complementation interaction between native forms of HaIAA27 and HaHSFA9. An auxin-resistant form of HaIAA27 was overexpressed in transgenic tobacco seeds, leading to effects consistent with down-regulation of the ortholog HSFA9 gene, effects not seen with the native HaIAA27 form. Repression of HSFs by HaIAA27 is thus likely alleviated by auxin in maturing seeds. We show that HSFs such as HaHSFA9 are targets of Aux/IAA protein repression. Because HaHSFA9 controls a genetic program involved in seed longevity and embryonic desiccation tolerance, our findings would suggest a mechanism by which these processes can be auxin regulated. Aux/IAA-mediated repression involves transcription factors distinct from ARFs. This finding widens interpretation of auxin responses.