title: Ethylene-orchestrated circuitry coordinates a seedling's response to soil cover and etiolated growth.
abstract: The early life of terrestrial seed plants often starts under the soil in subterranean darkness. Over time and through adaptation, plants have evolved an elaborate etiolation process that enables seedlings to emerge from soil and acquire autotrophic ability. This process, however, requires seedlings to be able to sense the soil condition and relay this information accordingly to modulate both the seedlings' growth and the formation of photosynthetic apparatus. The mechanism by which soil overlay drives morphogenetic changes in plants, however, remains poorly understood, particularly with regard to the means by which the cellular processes of different organs are coordinated in response to disparate soil conditions. Here, we illustrate that the soil overlay quantitatively activates seedlings' ethylene production, and an EIN3/EIN3-like 1-dependent ethylene-response cascade is required for seedlings to successfully emerge from the soil. Under soil, an ERF1 pathway is activated in the hypocotyl to slow down cell elongation, whereas a PIF3 pathway is activated in the cotyledon to control the preassembly of photosynthetic machinery. Moreover, this latter PIF3 pathway appears to be coupled to the ERF1-regulated upward-growth rate. The coupling of these two pathways facilitates the synchronized progression of etioplast maturation and hypocotyl growth, which, in turn, ultimately enables seedlings to maintain the amount of protochlorophyllide required for rapid acquisition of photoautotrophic capacity without suffering from photooxidative damage during the dark-to-light transition. Our findings illustrate the existence of a genetic signaling pathway driving soil-induced plant morphogenesis and define the specific role of ethylene in orchestrating organ-specific soil responses in Arabidopsis seedlings.
authors.affiliation: Peking-Yale Joint Center for Plant Molecular Genetics and Agro-biotechnology, National Key Laboratory of Protein and Plant Gene Research, and Peking-Tsinghua Center for Life Sciences, College of Life Sciences, Peking University, Beijing 100871, China.
authors.forename: Shangwei
authors.initials: S
authors.lastname: Zhong
authors.forename: Hui
authors.initials: H
authors.lastname: Shi
authors.forename: Chang
authors.initials: C
authors.lastname: Xue
authors.forename: Ning
authors.initials: N
authors.lastname: Wei
authors.forename: Hongwei
authors.initials: H
authors.lastname: Guo
authors.forename: Xing Wang
authors.initials: XW
authors.lastname: Deng
mesh_terms: D017360:Arabidopsis / Q000254:growth & development*; D029681:Arabidopsis Proteins / Q000378:metabolism; D002849:Chromatography, Gas; D004268:DNA-Binding Proteins; D005030:Ethylenes / Q000378:metabolism*; D064527:Etiolation / Q000502:physiology*; D018525:Germination / Q000502:physiology*; D006651:Histocytochemistry; D018613:Microscopy, Confocal; D008856:Microscopy, Fluorescence; D009687:Nuclear Proteins / Q000378:metabolism; D010454:Peptide Termination Factors / Q000378:metabolism; D011521:Protochlorophyllide / Q000096:biosynthesis; D060888:Real-Time Polymerase Chain Reaction; D036226:Seedlings / Q000254:growth & development*; D012987:Soil / Q000737:chemistry*; D014157:Transcription Factors / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D004268:DNA-Binding Proteins; C106987:EIN3 protein, Arabidopsis; D005030:Ethylenes; D009687:Nuclear Proteins; D010454:Peptide Termination Factors; D012987:Soil; D014157:Transcription Factors; C494978:eukaryotic release factor 1, Arabidopsis; D011521:Protochlorophyllide; C036216:ethylene
keywords: ROS; cell death; chlorophyll biosynthesis; plant hormone ethylene