TY - JOUR

T1 - The Proline-rich Family Protein EXTENSIN33 Is Required For Etiolated Arabidopsis thaliana Hypocotyl Growth

AU - Zdanio, Malgorzata

AU - Boron, Agnieszka Karolina

AU - Balcerowicz, Daria

AU - Schoenaers, Sébastjen

AU - Markakis, Marios Nektarios

AU - Mouille, Grégory

AU - Pintelon, Isabel

AU - Suslov, Dmitry

AU - Gonneau, Martine

AU - Höfte, Herman

AU - Vissenberg, Kris

N1 - Publisher Copyright: © 2020 The Author(s) 2020. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved.

PY - 2020/4/8

Y1 - 2020/4/8

N2 - Growth of etiolated Arabidopsis hypocotyls is biphasic. During the first phase, cells elongate slowly and synchronously. At 48hrs after imbibition, cells at the hypocotyl base accelerate their growth. Subsequently, this rapid elongation propagates through the hypocotyl from base to top. It is largely unclear what regulates the switch from slow to fast elongation. Reverse genetics-based screening for hypocotyl phenotypes identified three independent mutant lines of At1g70990, a short extensin family protein which we named EXT33, with shorter etiolated hypocotyls during the slow elongation phase. However, at 72hrs after imbibition, these dark-grown mutant hypocotyls start to elongate faster than the wild type. As a result, fully mature 8-day-old dark-grown hypocotyls were significantly longer than wild types. Mutant roots showed no growth phenotype. In line with these results, analysis of native promoter-driven transcriptional fusion lines revealed that in dark-grown hypocotyls expression occurred in the epidermis and cortex and that it was strongest in the growing part. Confocal and spinning disk microscopy on C-terminal protein-GFP fusion lines, localized the EXT33-protein to the ER and cell wall. Fourier Transformed Infrared (FT-IR) Microspectroscopy identified subtle changes in cell wall composition between wild type and the mutant, reflecting altered cell wall biomechanics measured by constant load extensometry. Our results indicate that the EXT33 short extensin family protein is required during the first phase of dark-grown hypocotyl elongation and that it regulates the moment and extent of the growth acceleration by modulating cell wall extensibility.

AB - Growth of etiolated Arabidopsis hypocotyls is biphasic. During the first phase, cells elongate slowly and synchronously. At 48hrs after imbibition, cells at the hypocotyl base accelerate their growth. Subsequently, this rapid elongation propagates through the hypocotyl from base to top. It is largely unclear what regulates the switch from slow to fast elongation. Reverse genetics-based screening for hypocotyl phenotypes identified three independent mutant lines of At1g70990, a short extensin family protein which we named EXT33, with shorter etiolated hypocotyls during the slow elongation phase. However, at 72hrs after imbibition, these dark-grown mutant hypocotyls start to elongate faster than the wild type. As a result, fully mature 8-day-old dark-grown hypocotyls were significantly longer than wild types. Mutant roots showed no growth phenotype. In line with these results, analysis of native promoter-driven transcriptional fusion lines revealed that in dark-grown hypocotyls expression occurred in the epidermis and cortex and that it was strongest in the growing part. Confocal and spinning disk microscopy on C-terminal protein-GFP fusion lines, localized the EXT33-protein to the ER and cell wall. Fourier Transformed Infrared (FT-IR) Microspectroscopy identified subtle changes in cell wall composition between wild type and the mutant, reflecting altered cell wall biomechanics measured by constant load extensometry. Our results indicate that the EXT33 short extensin family protein is required during the first phase of dark-grown hypocotyl elongation and that it regulates the moment and extent of the growth acceleration by modulating cell wall extensibility.

KW - Arabidopsis thaliana

KW - cell wall

KW - etiolated hypocotyl growth

KW - FT-IR analysis

KW - short extensin

KW - creep test

KW - Etiolated hypocotyl growth

KW - Creep test

KW - Short extensin

KW - Cell wall

KW - ROOT

KW - CELL-WALL PROTEIN

KW - GLYCOSYLPHOSPHATIDYLINOSITOL-ANCHORED PROTEINS

KW - FT-IR

KW - IDENTIFICATION

KW - EXTENSIN

KW - ELONGATION

KW - POLYSACCHARIDES

KW - EXPRESSION

KW - PLANT-GROWTH

UR - http://www.scopus.com/inward/record.url?scp=85086523983&partnerID=8YFLogxK

UR - https://www.mendeley.com/catalogue/b3e71bcd-79f7-34c1-9d33-1ae242060c7a/

U2 - 10.1093/pcp/pcaa049

DO - 10.1093/pcp/pcaa049

M3 - Article

VL - 61

SP - 1191

EP - 1203

JO - Plant and Cell Physiology

JF - Plant and Cell Physiology

SN - 0032-0781

IS - 6

ER -