Feedback loop promotes sucrose accumulation in cotyledons to facilitate sugar-ethylene signaling-mediated, etiolated-seedling greening

Cell Rep. 2022 Mar 15;38(11):110529. doi: 10.1016/j.celrep.2022.110529.

Abstract

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.

Keywords: CP: Developmental Biology; CP: Plants; EIN3; ETHYLENE-INSENSITIVE3; SUC2; SUCROSE transporter 2; cotyledon greening; ethylene; phyA; phytochrome A; sucrose phloem loading.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Arabidopsis Proteins* / metabolism
  • Arabidopsis* / metabolism
  • Cotyledon / metabolism
  • Ethylenes
  • Feedback
  • Gene Expression Regulation, Plant
  • Light
  • Seedlings / metabolism
  • Soil
  • Sucrose
  • Sugars

Substances

  • Arabidopsis Proteins
  • Ethylenes
  • Soil
  • Sugars
  • Sucrose
  • ethylene