---
OA_type: closed access
_id: '22366'
abstract:
- lang: eng
  text: Gravitropism is a fundamental adaptive response in plants that enables directional
    growth to optimize resource acquisition. In this study, we employed forward genetic
    screening to identify Arabidopsis mutants with defective hypocotyl gravitropism
    and isolated the short and agravitropic hypocotyl in dark1 (sad1) mutant, which
    carries a point mutation (G110E) in the SAC1 gene encoding a phosphoinositide
    phosphatase. Deficiency of SAC1 disrupted gravity-induced polar localization of
    PIN3 in endodermal cells, impairing auxin redistribution and leading to hypocotyl
    gravitropism defects. Subcellular localization analysis revealed that SAC1 is
    partially localized to the PVC/tonoplast and participates in late endosomal trafficking.
    The sac1 mutation leads to abnormal vacuolar morphology, which is associated with
    defects in amyloplast sedimentation during the gravitropic response in Arabidopsis
    shoots. We further revealed that SAC1 interacts with GRV2, a key regulator of
    the late endocytic pathway, and that both proteins cooperatively regulate shoot
    gravitropism. In summary, this study identified SAC1 as a regulator of shoot gravitropism,
    revealing its important role in modulating vacuolar homeostasis, amyloplast sedimentation,
    PIN3 trafficking, and auxin distribution. These findings provide insights into
    the molecular mechanisms linking membrane transport to environmental adaptation
    in plants.
acknowledgement: We acknowledge Prof. Dolf Weijers (Wageningen University), Prof.Karin
  Schumacher (Heidelberg University), Prof. Yohann Boutt ´e(Universit ´e de Bordeaux),
  and Prof. Jinbo Shen (Zhejiang A&FUniversity) for providing published plasmids and
  Arabidopsislines. We thank Dr. Gergely Moln ´ar (ISTA) for help with NGS dataanalysis,
  and Prof. Jianru Zuo (IGDB, CAS), Prof. Chengbin Xiang(USTC), and Prof. Zhong Zhao
  (USTC) for critical comments onthe manuscript. We thank the staff members of the
  Mass Spec-trometry System at the National Facility for Protein Science inShanghai
  (NFPS), Zhangjiang Lab, China for providing technicalsupport and assistance in data
  collection and analysis. This workwas supported by grants from the National Natural
  Science Foun-dation of China (32570366, and 32321001 to ST), the Natural Sci-ence
  Foundation of Anhui Province (2508085QC070 to MK), theFundamental Research Funds
  for the Central Universities(WK9100250095 to MK, and WK9100000021 to ST), the ForestryBureau
  of Anhui Province (AHLYJBGS-2024-01 to ST), the Centerfor Advanced Interdisciplinary
  Science and Biomedicine of IHM,Division of Life Sciences and Medicine, University
  of Science andTechnology of China (QYPY20220012 to ST), the USTC ResearchFunds of
  the Double First-Class Initiative (YD9100002016 to ST),and start-up funding from
  the University of Science and Technol-ogy of China and the Chinese Academy of Sciences(GG9100007007,
  KY9100000026, KY9100000051, XKTS-202591014,XKTS-2026910122, and KJ2070000079 to
  ST).
article_number: e71042
article_processing_charge: No
article_type: original
author:
- first_name: Lianghanxiao
  full_name: Sun, Lianghanxiao
  last_name: Sun
- first_name: Wenxin
  full_name: Jia, Wenxin
  last_name: Jia
- first_name: Yanbo
  full_name: Mao, Yanbo
  last_name: Mao
- first_name: Xin
  full_name: Li, Xin
  last_name: Li
- first_name: Mengjuan
  full_name: Kong, Mengjuan
  last_name: Kong
- first_name: Ji
  full_name: She, Ji
  last_name: She
- first_name: Jiří
  full_name: Friml, Jiří
  id: 4159519E-F248-11E8-B48F-1D18A9856A87
  last_name: Friml
  orcid: 0000-0002-8302-7596
- first_name: Shutang
  full_name: Tan, Shutang
  id: 2DE75584-F248-11E8-B48F-1D18A9856A87
  last_name: Tan
  orcid: 0000-0002-0471-8285
citation:
  ama: Sun L, Jia W, Mao Y, et al. Regulation of shoot gravitropism and branching
    angle by the GRV2-SAC1 axis in Arabidopsis. <i>The Plant Journal</i>. 2026;127(1).
    doi:<a href="https://doi.org/10.1111/tpj.71042">10.1111/tpj.71042</a>
  apa: Sun, L., Jia, W., Mao, Y., Li, X., Kong, M., She, J., … Tan, S. (2026). Regulation
    of shoot gravitropism and branching angle by the GRV2-SAC1 axis in Arabidopsis.
    <i>The Plant Journal</i>. Wiley. <a href="https://doi.org/10.1111/tpj.71042">https://doi.org/10.1111/tpj.71042</a>
  chicago: Sun, Lianghanxiao, Wenxin Jia, Yanbo Mao, Xin Li, Mengjuan Kong, Ji She,
    Jiří Friml, and Shutang Tan. “Regulation of Shoot Gravitropism and Branching Angle
    by the GRV2-SAC1 Axis in Arabidopsis.” <i>The Plant Journal</i>. Wiley, 2026.
    <a href="https://doi.org/10.1111/tpj.71042">https://doi.org/10.1111/tpj.71042</a>.
  ieee: L. Sun <i>et al.</i>, “Regulation of shoot gravitropism and branching angle
    by the GRV2-SAC1 axis in Arabidopsis,” <i>The Plant Journal</i>, vol. 127, no.
    1. Wiley, 2026.
  ista: Sun L, Jia W, Mao Y, Li X, Kong M, She J, Friml J, Tan S. 2026. Regulation
    of shoot gravitropism and branching angle by the GRV2-SAC1 axis in Arabidopsis.
    The Plant Journal. 127(1), e71042.
  mla: Sun, Lianghanxiao, et al. “Regulation of Shoot Gravitropism and Branching Angle
    by the GRV2-SAC1 Axis in Arabidopsis.” <i>The Plant Journal</i>, vol. 127, no.
    1, e71042, Wiley, 2026, doi:<a href="https://doi.org/10.1111/tpj.71042">10.1111/tpj.71042</a>.
  short: L. Sun, W. Jia, Y. Mao, X. Li, M. Kong, J. She, J. Friml, S. Tan, The Plant
    Journal 127 (2026).
das_tickbox: '1'
dataavailabilitystatement: Biological materials (seeds, plasmids) are available upon
  request from ST (sttan@ustc.edu.cn). The data that support the findings of this study
  are available on request from the corresponding author. The data are not publicly
  available due to privacy or ethical restrictions.
date_created: 2026-07-19T22:01:47Z
date_published: 2026-07-01T00:00:00Z
date_updated: 2026-07-20T13:53:44Z
day: '01'
department:
- _id: JiFr
doi: 10.1111/tpj.71042
external_id:
  pmid:
  - '42438075'
intvolume: '       127'
issue: '1'
keyword:
- auxin
- SAC1
- GRV2
- PIN3
- vacuole
- gravitropism
- Arabidopsis
language:
- iso: eng
month: '07'
oa_version: None
pmid: 1
publication: The Plant Journal
publication_identifier:
  eissn:
  - 1365-313X
  issn:
  - 0960-7412
publication_status: published
publisher: Wiley
quality_controlled: '1'
researchdata_availability: upon request
scopus_import: '1'
status: public
supplementarymaterial: yes
title: Regulation of shoot gravitropism and branching angle by the GRV2-SAC1 axis
  in Arabidopsis
type: journal_article
user_id: 2DF688A6-F248-11E8-B48F-1D18A9856A87
volume: 127
year: '2026'
...