The members of early auxin response gene family, Aux/IAA, encode negative regulators of auxin signaling but play a central role in auxin‐mediated plant development. Here we report the interaction of an Aux/IAA protein, AtIAA14, with Drought‐induced‐19 (Di19‐3) protein and its possible role in auxin signaling. The Atdi19‐3 mutant seedlings develop short hypocotyl, both in light and dark, and are compromised in temperature‐induced hypocotyl elongation. The mutant plants accumulate more IAA and also show altered expression of NIT2, ILL5, and YUCCA genes involved in auxin biosynthesis and homeostasis, along with many auxin responsive genes like AUX1 and MYB77. Atdi19‐3 seedlings show enhanced root growth inhibition when grown in the medium supplemented with auxin. Nevertheless, number of lateral roots is low in Atdi19‐3 seedlings grown on the basal medium. We have shown that AtIAA14 physically interacts with AtDi19‐3 in yeast two‐hybrid (Y2H), bimolecular fluorescence complementation, and in vitro pull‐down assays. However, the auxin‐induced degradation of AtIAA14 in the Atdi19‐3 seedlings was delayed. By expressing pIAA14::mIAA14‐GFP in Atdi19‐3 mutant background, it became apparent that both Di19‐3 and AtIAA14 work in the same pathway and influence lateral root development in Arabidopsis. Gain‐of‐function slr‐1/iaa14 (slr) mutant, like Atdi19‐3, showed tolerance to abiotic stress in seed germination and cotyledon greening assays. The Atdi19‐3 seedlings showed enhanced sensitivity to ethylene in triple response assay and AgNO₃, an ethylene inhibitor, caused profuse lateral root formation in the mutant seedlings. These observations suggest that AtDi19‐3 interacting with AtIAA14, in all probability, serves as a positive regulator of auxin signaling and also plays a role in some ethylene‐mediated responses in Arabidopsis.

中文翻译：

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干旱诱导蛋白 (Di19-3) 通过与拟南芥中的 IAA14 相互作用在生长素信号传导中发挥作用。

早期生长素反应基因家族的成员Aux/IAA编码生长素信号传导的负调控因子，但在生长素介导的植物发育中发挥核心作用。在这里，我们报告了 Aux/IAA 蛋白 AtIAA14 与干旱诱导的 19 (Di19-3) 蛋白的相互作用及其在生长素信号传导中的可能作用。Atdi19-3突变体幼苗在光照和黑暗中都发育出短的下胚轴，并且在温度诱导的下胚轴伸长中受到损害。突变植物积累了更多的 IAA，并且还显示出参与生长素生物合成和体内平衡的NIT2、ILL5和YUCCA基因的表达改变，以及许多生长素响应基因如AUX1和MYB77。Atdi19-3幼苗在补充有生长素的培养基中生长时显示出增强的根生长抑制作用。然而，在基础培养基上生长的Atdi19-3幼苗的侧根数量较少。我们已经证明 AtIAA14 在酵母双杂交 (Y2H)、双分子荧光互补和体外下拉试验中与 AtDi19-3 发生物理相互作用。然而，生长素诱导的Atdi19-3幼苗中 AtIAA14 的降解被延迟。通过在Atdi19-3突变背景中表达pIAA14::mIAA14-GFP，很明显 Di19-3 和 AtIAA14 在相同的途径中起作用并影响拟南芥的侧根发育。函数增益slr-1/iaa14 ( slr) 突变体，如Atdi19-3，在种子萌发和子叶绿化试验中表现出对非生物胁迫的耐受性。Atdi19-3幼苗在三重反应试验中对乙烯的敏感性增强，而乙烯抑制剂 AgNO 3_导致突变幼苗大量侧根形成。这些观察结果表明，AtDi19-3 与 AtIAA14 相互作用，很可能是生长素信号的正调节剂，并且在拟南芥中的一些乙烯介导的反应中也起作用。