The Key Laboratory of Biotechnology for Medicinal Plants of Jiangsu Province, Jiangsu Normal University, Xuzhou, Jiangsu 221116, People's Republic of China.
School of Life Science, Jiangsu Normal University, Xuzhou, Jiangsu 221116, People's Republic of China.
Cell Rep. 2022 Mar 15;38(11):110529. doi: 10.1016/j.celrep.2022.110529.
De-etiolation is indispensable for seedling survival and development. However, how sugars regulate de-etiolation and how sugars induce ethylene (ET) for seedlings to grow out of soil remain elusive. Here, we reveal how a sucrose (Suc) feedback loop promotes de-etiolation by inducing ET biosynthesis. Under darkness, Suc in germinating seeds preferentially induces 1-amino-cyclopropane-1-carboxylate synthase (ACS7; encoding a key ET biosynthesis enzyme) and associated ET biosynthesis, thereby activating ET core component ETHYLENE-INSENSITIVE3 (EIN3). Activated EIN3 directly inhibits the function of Suc transporter 2 (SUC2; a major Suc transporter) to block Suc export from cotyledons and thereby elevate Suc accumulation of cotyledons to induce ET. Under light, ET-activated EIN3 directly inhibits the function of phytochrome A (phyA; a de-etiolation inhibitor) to promote de-etiolation. We therefore propose that under darkness, the Suc feedback loop (Suc-ACS7-EIN3-|SUC2-Suc) promotes Suc accumulation in cotyledons to guarantee ET biosynthesis, facilitate de-etiolation, and enable seedlings to grow out of soil.
去黄化对于幼苗的生存和发育是必不可少的。然而，糖如何调节去黄化以及糖如何诱导乙烯（ET）使幼苗从土壤中生长出来，这些仍然难以捉摸。在这里，我们揭示了蔗糖（Suc）反馈环如何通过诱导 ET 生物合成来促进去黄化。在黑暗中，萌发种子中的 Suc 优先诱导 1-氨基环丙烷-1-羧酸合酶（ACS7；编码关键 ET 生物合成酶）和相关的 ET 生物合成，从而激活 ET 核心成分 ETHYLENE-INSENSITIVE3（EIN3）。激活的 EIN3 直接抑制 Suc 转运体 2（SUC2；主要的 Suc 转运体）的功能，阻止 Suc 从子叶中输出，从而提高子叶中 Suc 的积累以诱导 ET。在光照下，ET 激活的 EIN3 直接抑制光敏色素 A（phyA；去黄化抑制剂）的功能，以促进去黄化。因此，我们提出，在黑暗中，Suc 反馈环（Suc-ACS7-EIN3-|SUC2-Suc）促进子叶中 Suc 的积累，以保证 ET 生物合成，促进去黄化，并使幼苗能够从土壤中生长出来。
