SmARF8, a transcription factor involved in parthenocarpy in eggplant
SmARF8, a transcription factor involved in parthenocarpy in eggplant
复制标题
DOI：
10.1007/s00438-015-1088-5
复制
发表时间：
2016-02-01
影响因子：
3.1
通讯作者：
Mao, Weihai
中科院分区：
文献类型：
--
作者：
Du, Liming;Bao, Chonglai;Mao, Weihai
单性结实对消费者来说是一个非常有吸引力的特性，尤其是茄子，其种子会导致果肉褐变和苦味。然而，茄子单性结实的分子机制仍不清楚。先前已在模式物种（例如拟南芥和番茄）中显示一些生长素反应因子在这一过程中发挥重要作用。在这里，我们鉴定了一种天然单性结实突变体，并表明与野生型植物相比，来自茄子的 ARF8 (SmARF8) 在芽中表达下调。 SmARF8 的进一步表征表明它是一种核蛋白和活性转录调节因子。我们确定SmARF8的629-773位氨基酸作为转录激活结构域，SmARF8的C末端是蛋白结合结构域，并且SmARF8可能形成同源二聚体。茄子中的表达分析表明，SmARF8 在所有组织和器官中普遍表达，并且对生长素有反应。含有 SmARF8 RNA 干扰的茄子转基因品系在未受精的花中表现出单性结实，表明 SmARF8 负向调节果实形成。有趣的是，SmARF8 过表达的拟南芥品系也诱导单性结实。这些结果表明SmARF8可以通过结构域III和IV影响生长素/吲哚乙酸阻遏物与SmARF8的二聚化，从而诱导果实发育。此外，引入SmARF8全长cDNA可以部分补充拟南芥arf8-1和arf8-4突变体中的单性结实表型。总的来说，我们的结果表明 SmARF8 可能作为参与茄子单性结实果实发育的关键负调节因子。这些发现使人们对导致单性结实的保守机制有了更多的了解，其中生长素信号传导起着关键作用，并为茄子育种提供了潜在的靶点。
Parthenocarpic fruit is a very attractive trait for consumers and especially in eggplants where seeds can lead to browning of the flesh and bitterness. However, the molecular mechanisms underlying parthenocarpy in eggplant still remain unknown. Some auxin response factors have been previously shown in model species, such as Arabidopsis and tomato, to play an important role in such a process. Here, we have identified a natural parthenocarpic mutant and showed that ARF8 from eggplant (SmARF8), is down-regulated in buds compared to wild-type plants. Further characterization of SmARF8 showed that it is a nuclear protein and an active transcriptional regulator. We determined that amino acids 629-773 of SmARF8 act as the transcriptional activation domain, the C terminus of SmARF8 is the protein-binding domain, and that SmARF8 might form homodimers. Expression analysis in eggplant showed that SmARF8 is expressed ubiquitously in all tissues and organs and is responsive to auxin. Eggplant transgenic lines harboring RNA interference of SmARF8 exhibited parthenocarpy in unfertilized flowers, suggesting that SmARF8 negatively regulates fruit initiation. Interestingly, SmARF8-overexpressing Arabidopsis lines also induced parthenocarpy. These results indicate that SmARF8 could affect the dimerization of auxin/indole acetic acid repressors with SmARF8 via domains III and IV and thus induce fruit development. Furthermore, the introduction of SmARF8 full-length cDNA could partially complement the parthenocarpic phenotypes in Arabidopsis arf8-1 and arf8-4 mutants. Collectively, our results demonstrate that SmARF8 may act as a key negative regulator involved in parthenocarpic fruit development of eggplant. These findings give more insights into the conserved mechanisms leading to parthenocarpy in which auxin signaling plays a pivotal role, and provide potential target for eggplant breeding.