Translational control of phloem development by RNA G-quadruplex-JULGI determines plant sink strength
Translational control of phloem development by RNA G-quadruplex-JULGI determines plant sink strength
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DOI：
10.1038/s41477-018-0157-2
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发表时间：
2018-06-01
期刊：
影响因子：
18
通讯作者：
Hwang, Ildoo
中科院分区：
文献类型：
--
作者：
Cho, Hyunwoo;Cho, Hyun Seob;Hwang, Ildoo
植物维管系统的出现是陆地定居的先决条件；然而，光合成运输系统是如何在植物进化过程中建立的，目前还不清楚。在这里，我们发现了一个新的韧皮部发育的翻译调控模块，涉及锌指蛋白JULGI(JUL)及其靶标Max2 1-LIKE4/5(SMXL4/5)mRNAs的5‘非翻译区(UTRs)，它在维管束植物中是唯一保守的。JUL在SMXL4/5的5‘非编码区直接结合并诱导RNAG-四联体，是韧皮部分化的关键启动子。我们发现，RNAG-四链的形成抑制了SMXL4/5的翻译，并限制了韧皮部的分化。反过来，朱尔缺乏促进韧皮部的形成，并显著增加每粒种子的库容量。我们认为，JUL/5‘UTRG-四链模块的翻译调控是韧皮部建立的一个主要决定因素，从而决定了碳向下沉组织的分配，并且这一机制是维管植物出现过程中的一个关键发明。
The emergence of a plant vascular system was a prerequisite for the colonization of land; however, it is unclear how the photo-synthate transporting system was established during plant evolution. Here, we identify a novel translational regulatory module for phloem development involving the zinc-finger protein JULGI (JUL) and its targets, the 5' untranslated regions (UTRs) of the SUPPRESSOR OF MAX2 1-LIKE4/5 (SMXL4/5) mRNAs, which is exclusively conserved in vascular plants. JUL directly binds and induces an RNA G-quadruplex in the 5' UTR of SMXL4/5, which are key promoters of phloem differentiation. We show that RNA G-quadruplex formation suppresses SMXL4/5 translation and restricts phloem differentiation. In turn, JUL deficiency promotes phloem formation and strikingly increases sink strength per seed. We propose that the translational regulation by the JUL/5' UTR G-quadruplex module is a major determinant of phloem establishment, thereby determining carbon allocation to sink tissues, and that this mechanism was a key invention during the emergence of vascular plants.