Ancestral function but divergent epigenetic regulation of HAIKU2 reveals routes of seed developmental evolution
Ancestral function but divergent epigenetic regulation of HAIKU2 reveals routes of seed developmental evolution
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HAIKU2 的祖先功能但不同的表观遗传调控揭示了种子发育进化的途径
DOI：
10.1016/j.molp.2022.09.002
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发表时间：
2022-10-04
期刊：
影响因子：
27.5
通讯作者：
Ni，Min
中科院分区：
文献类型：
--
作者：
Wu，Di;Wei，Yiming;Ni，Min
进化是由多种机制驱动的。胚胎与胚乳比例的定向增加是被子植物的进化趋势。胚乳构成了禾本科植物和一些双子叶植物种子体积的主要部分。然而，在其他双子叶植物中，例如拟南芥和大豆，胚乳增殖较早，随后胚胎生长以取代胚乳。拟南芥富含亮氨酸的重复受体蛋白激酶 AtHAIKU2 (AtIKU2) 是早期胚乳增殖的关键调节因子。在本研究中，我们发现来自短柄草、水稻和大豆的IKU2可以补充Atiku2异常的种子发育表型，而AtIKU2还可以挽救短柄草BdIKU2敲除突变体种子中缺陷的胚乳增殖。AtIKU2和大豆GmIKU2在受精后几天活跃表达。此后，AtIKU2 的表达被 FIS-PRC2 复合物介导的 H3K27me3 抑制。大豆GmIKU2基因座也富含H3K27me3标记。组蛋白甲基转移酶 AtMEA 是十字花科植物所特有的，但大豆中的一个 GmSWN 在种子发育中发挥着与 AtMEA 类似的作用。相比之下，BdIKU2 和水稻 OsIKU2 基因座持续表达并且缺乏 H3K27me3 标记。总而言之，这些结果表明 IKU2 基因保留了祖先的功能，但由 PRC2 介导的表观遗传沉默控制的表达持续时间有助于不同物种中胚乳增殖的沉默或持续。我们的研究揭示了一种表观遗传机制，可驱动截然不同的种子个体发育的发展。
Evolution is driven by various mechanisms. A directional increase in the embryo to endosperm ratio is an evolutionary trend within the angiosperms. The endosperm constitutes a major portion of the seed volume inPoalesand some dicots. However, in other dicots such asArabidopsisand soybean, the endosperm proliferates early, followed by embryo growth to replace the endosperm. TheArabidopsisleucine-rich repeat receptor protein kinase AtHAIKU2 (AtIKU2) is a key regulator of early endosperm proliferation. In this study, we found thatIKU2sfromBrachypodium, rice, and soybean can complement the abnormal seed developmental phenotype ofAtiku2, whileAtIKU2also rescues the defective endosperm proliferation in theBrachypodium BdIKU2knockout mutant seeds.AtIKU2and soybeanGmIKU2are actively expressed a few days after fertilization. Thereafter, expression ofAtIKU2is suppressed by the FIS-PRC2 complex-mediated H3K27me3. The soybeanGmIKU2locus is also enriched with H3K27me3 marks. The histone methyltransferase AtMEA is unique to Brassicaceae, but one GmSWN in soybean plays a similar role in seed development as AtMEA. By contrast, theBdIKU2and riceOsIKU2loci are continuously expressed and are devoid of H3K27me3 marks. Taken together, these results suggest thatIKU2genes retain an ancestral function, but the duration of their expression that is controlled by PRC2-mediated epigenetic silencing contributes to silenced or persistent endosperm proliferation in different species. Our study reveals an epigenetic mechanism that drives the development of vastly different seed ontogenies.