Abstract
Peptides derived from non-functional precursors play important roles in various developmental processes, but also in (a)biotic stress signaling. Our (phospho)proteome-wide analyses of C-TERMINALLY ENCODED PEPTIDE 5 (CEP5)-mediated changes revealed an impact on abiotic stress-related processes. Drought has a dramatic impact on plant growth, development and reproduction, and the plant hormone auxin plays a role in drought responses. Our genetic, physiological, biochemical, and pharmacological results demonstrated that CEP5-mediated signaling is relevant for osmotic and drought stress tolerance in Arabidopsis, and that CEP5 specifically counteracts auxin effects. Specifically, we found that CEP5 signaling stabilizes AUX/IAA transcriptional repressors, suggesting the existence of a novel peptide-dependent control mechanism that tunes auxin signaling. These observations align with the recently described role of AUX/IAAs in stress tolerance and provide a novel role for CEP5 in osmotic and drought stress tolerance.
Highlights
The proteome and phosphoproteome of C-TERMINALLY ENCODED PEPTIDE 5 (CEP5) overexpressing Arabidopsis seedlings have been determined
Proteome and phosphoproteome analyses reveal a potential role for CEP5 in abiotic stress response— CEP5 has been shown to play a role in shoot and root growth [5, 56, 57], possibly through interaction with the CEP RECEPTOR 1 (CEPR1)/XYLEM INTERMIXED WITH PHLOEM 1 (XIP1) and/or
These results indicate that CEP5 interferes with degradation of auxin/indole-3-acetic acid inducible (AUX/indole-3-acetic acid (IAA)), that this occurs in the absence of CEP receptors as shown in yeast, and that this is likely by targeting proteasome activity
Summary
The proteome and phosphoproteome of CEP5 overexpressing Arabidopsis seedlings have been determined. We found that CEP5 signaling stabilizes AUX/IAA transcriptional repressors, suggesting the existence of a novel peptide-dependent control mechanism that tunes auxin signaling. Small signaling peptides are important in cell-cell communication to coordinate and integrate cellular functions [21, 22], as seen in the TRACHEARY ELEMENT DIFFERENTIATION INHIBITORY FACTOR (TDIF) - TDIF RECEPTOR (TDR) - BRASSINOSTEROID-INSENSITIVE2 (BIN2) signaling cascade that interferes with ARF - AUX/IAA interactions [18] Abiotic stresses, such as drought, have a dramatic impact on plant growth, development and reproduction [23], but little is known about the role of auxin in drought responses (24 –26) and even less about the involvement of peptides derived from non-functional precursors [27,28,29]. We assigned a novel role for CEP5 in drought stress response
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