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Translational control of phloem development by RNA G-quadruplex-JULGI …

  • 저널명NATURE PLANTS, 4(6):376-390. doi: 10.1038/s41477-018-0157-2
    • 담당교수Ildoo Hwang
    • 조회564
    • 작성자최고관리자
    • 2020-03-04


    ■ Abstract
    The emergence of a plant vascular system was a prerequisite for the colonization of land; however, it is unclear how the photosynthate 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.