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DOI number:

10.1016/j.mcpro.2026.101532

Journal:

Molecular & Cellular Proteomics

Key Words:

4C quantitative phosphoproteomics; Arabidopsis; force signaling; gravity-regulated phosphoprotein 1 (GREPH1); likelihood of interaction and function evaluation (LIFE) score; seconds of phosphorylation events

Abstract:

Plants perceive mechanical forces through phosphosignaling networks, but their relationship with gravity signaling remains elusive. To dissect gravity force signaling components, we performed SILIA-based phosphoproteomics on Arabidopsis aerial organs subjected to 20-s inversion or 30-s gravistimulation, identifying 2,733 and 2,878 phosphoproteins, respectively. Quantitative analysis revealed 34 significantly regulated phosphoproteins specific to inversion and 52 specific to gravistimulation. Inversion-specific phosphoproteins, associated with the initial calcium code, likely mediate calcium signals through EF-hand proteins, CPK1, and calmodulin-interacting proteins, potentially intersecting with receptor-like kinase-initiated MAPK cascades via RAF15 and MKK1/2 to induce gravitropic responses. Gravistimulation-specific phosphoproteins, linked to the secondary calcium code, function in calcium signaling/homeostasis (ACA8, ZAC, IQD2, ANNAT1), membrane vesicle trafficking (ABCG36, ARF-GAP8), and lipid signaling (PIP5K8/9), supporting auxin transport and stress signal transduction. Immunoblot validation confirmed treatment-associated phosphosites pS108-PATL3 and pS107-TREPH2, along with inversion-specific pS1145-ATEH2, exhibiting stem-specific phosphorylation enhancement and force-discriminatory responses. Functional analysis identified the integrin-like protein GREPH1 as a key gravitropism regulator, with greph1 mutants displaying reduced inflorescence stem gravicurvature. Notably, hyperphosphorylation of pS107-TREPH2 and pS1145-ATEH2 peaked at 20 to 50 s in greph1 mutants but persisted from 20 s to 2 h in WT plants. These findings establish a stem-enriched phosphorylation code for gravity force discrimination, with GREPH1 modulating spatiotemporal phosphoprotein dynamics and shoot gravicurvature, potentially functioning as a receptor reminiscent of sedimenting plastids.

Co-author:

Xiaoting Li, Manhin Leung, Al Burlingame, Zhi-Yong Wang, Minglei Yang, Yinglin Lu, Yuxing An, Yage Zhang, Zhu Yang, Weichuan Yu, Ning Li

First Author:

Nan Yang#, Sunny Sing Pun#, Emily Oi Ying Wong#, Shuaijian Dai#

Indexed by:

Journal paper

Document Type:

Article

Volume:

25

Issue:

4

Page Number:

101532

ISSN No.:

1535-9476

Translation or Not:

no

Date of Publication:

2026-02-19