---
OA_place: publisher
_id: '10083'
abstract:
- lang: eng
  text: "Plant motions occur across a wide spectrum of timescales, ranging from seed
    dispersal through bursting (milliseconds) and stomatal opening (minutes) to long-term
    adaptation of gross architecture. Relatively fast motions include water-driven
    growth as exemplified by root cell expansion under abiotic/biotic stresses or
    during gravitropism. A showcase is a root growth inhibition in 30 seconds triggered
    by the phytohormone auxin. However, the cellular and molecular mechanisms are
    still largely unknown. This thesis covers the studies about this topic as follows.
    By taking advantage of microfluidics combined with live imaging, pharmaceutical
    tools, and transgenic lines, we examined the kinetics of and causal relationship
    among various auxininduced rapid cellular changes in root growth, apoplastic pH,
    cytosolic Ca2+, cortical microtubule (CMT) orientation, and vacuolar morphology.
    We revealed that CMT reorientation and vacuolar constriction are the consequence
    of growth itself instead of responding directly to auxin. In contrast, auxin induces
    apoplast alkalinization to rapidly inhibit root growth in 30 seconds. This auxin-triggered
    apoplast alkalinization results from rapid H+- influx that is contributed by Ca2+
    inward channel CYCLIC NUCLEOTIDE-GATED CHANNEL 14 (CNGC14)-dependent Ca2+ signaling.
    To dissect which auxin signaling mediates the rapid apoplast alkalinization, we\r\ncombined
    microfluidics and genetic engineering to verify that TIR1/AFB receptors conduct
    a non-transcriptional regulation on Ca2+ and H+ -influx. This non-canonical pathway
    is mostly mediated by the cytosolic portion of TIR1/AFB. On the other hand, we
    uncovered, using biochemical and phospho-proteomic analysis, that auxin cell surface
    signaling component TRANSMEMBRANE KINASE 1 (TMK1) plays a negative role during
    auxin-trigger apoplast\r\nalkalinization and root growth inhibition through directly
    activating PM H+ -ATPases. Therefore, we discovered that PM H+ -ATPases counteract
    instead of mediate the auxintriggered rapid H+ -influx, and that TIR1/AFB and
    TMK1 regulate root growth antagonistically. This opposite effect of TIR1/AFB and
    TMK1 is consistent during auxin-induced hypocotyl elongation, leading us to explore
    the relation of two signaling pathways. Assisted with biochemistry and fluorescent
    imaging, we verified for the first time that TIR1/AFB and TMK1 can interact with
    each other. The ability of TIR1/AFB binding to membrane lipid provides a basis
    for the interaction of plasma membrane- and cytosol-localized proteins.\r\nBesides,
    transgenic analysis combined with genetic engineering and biochemistry showed
    that  vi\r\nthey do function in the same pathway. Particularly, auxin-induced
    TMK1 increase is TIR1/AFB dependent, suggesting TIR1/AFB regulation on TMK1. Conversely,
    TMK1 also regulates TIR1/AFB protein levels and thus auxin canonical signaling.
    To follow the study of rapid growth regulation, we analyzed another rapid growth
    regulator, signaling peptide RALF1. We showed that RALF1 also triggers a rapid
    and reversible growth inhibition caused by H + influx, highly resembling but not
    dependent on auxin. Besides, RALF1 promotes auxin biosynthesis by increasing expression
    of auxin biosynthesis enzyme YUCCAs and thus induces auxin signaling in ca. 1
    hour, contributing to the sustained RALF1-triggered growth inhibition. These studies
    collectively contribute to understanding rapid regulation on plant cell\r\ngrowth,
    novel auxin signaling pathway as well as auxin-peptide crosstalk. "
alternative_title:
- ISTA Thesis
article_processing_charge: No
author:
- first_name: Lanxin
  full_name: Li, Lanxin
  id: 367EF8FA-F248-11E8-B48F-1D18A9856A87
  last_name: Li
  orcid: 0000-0002-5607-272X
citation:
  ama: Li L. Rapid cell growth regulation in Arabidopsis. 2021. doi:<a href="https://doi.org/10.15479/at:ista:10083">10.15479/at:ista:10083</a>
  apa: Li, L. (2021). <i>Rapid cell growth regulation in Arabidopsis</i>. Institute
    of Science and Technology Austria. <a href="https://doi.org/10.15479/at:ista:10083">https://doi.org/10.15479/at:ista:10083</a>
  chicago: Li, Lanxin. “Rapid Cell Growth Regulation in Arabidopsis.” Institute of
    Science and Technology Austria, 2021. <a href="https://doi.org/10.15479/at:ista:10083">https://doi.org/10.15479/at:ista:10083</a>.
  ieee: L. Li, “Rapid cell growth regulation in Arabidopsis,” Institute of Science
    and Technology Austria, 2021.
  ista: Li L. 2021. Rapid cell growth regulation in Arabidopsis. Institute of Science
    and Technology Austria.
  mla: Li, Lanxin. <i>Rapid Cell Growth Regulation in Arabidopsis</i>. Institute of
    Science and Technology Austria, 2021, doi:<a href="https://doi.org/10.15479/at:ista:10083">10.15479/at:ista:10083</a>.
  short: L. Li, Rapid Cell Growth Regulation in Arabidopsis, Institute of Science
    and Technology Austria, 2021.
corr_author: '1'
date_created: 2021-10-04T13:33:10Z
date_published: 2021-10-06T00:00:00Z
date_updated: 2026-04-16T12:20:41Z
day: '06'
ddc:
- '575'
degree_awarded: PhD
department:
- _id: GradSch
- _id: JiFr
doi: 10.15479/at:ista:10083
ec_funded: 1
file:
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fulldoi: https://doi.org/10.15479/at:ista:10083
has_accepted_license: '1'
language:
- iso: eng
license: https://creativecommons.org/licenses/by-nc-nd/4.0/
month: '10'
oa: 1
oa_version: Published Version
project:
- _id: 2564DBCA-B435-11E9-9278-68D0E5697425
  call_identifier: H2020
  grant_number: '665385'
  name: International IST Doctoral Program
- _id: 26B4D67E-B435-11E9-9278-68D0E5697425
  grant_number: '25351'
  name: 'A Case Study of Plant Growth Regulation: Molecular Mechanism of Auxin-mediated
    Rapid Growth Inhibition in Arabidopsis Root'
publication_identifier:
  issn:
  - 2663-337X
publication_status: published
publisher: Institute of Science and Technology Austria
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status: public
supervisor:
- first_name: Jiří
  full_name: Friml, Jiří
  id: 4159519E-F248-11E8-B48F-1D18A9856A87
  last_name: Friml
  orcid: 0000-0002-8302-7596
title: Rapid cell growth regulation in Arabidopsis
tmp:
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  legal_code_url: https://creativecommons.org/licenses/by-nc-nd/4.0/legalcode
  name: Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International
    (CC BY-NC-ND 4.0)
  short: CC BY-NC-ND (4.0)
type: dissertation
user_id: ba8df636-2132-11f1-aed0-ed93e2281fdd
year: '2021'
...