Signaling by a tyrosine-sulfated peptide balances growth and osmotic stress response in rice
Yejin ShimiD, Ellen Youngsoo RimiD, Jin C.-Y. Liao, Myeong‐Je ChoiD, George AustiniD, Patrick W. Carlos, Sameer S. KulkarniiD, Richard J. PayneiD, María Florencia ErcoliiD, Pamela C. RonaldiD
Abstract
Peptide hormone signaling coordinates plant growth and osmotic stress responses, yet how the transition between these responses is regulated remains poorly understood. Here, we investigated the function of the rice PLANT PEPTIDES CONTAINING SULFATED TYROSINE 8 (OsPSY8) peptide in osmotic stress responses. OsPSY8 was predominantly expressed in root tissues under non-stress conditions, with preferential expression in lateral roots where it promoted root growth. Osmotic stress rapidly reduced OsPSY8 expression in roots through the OsWRKY24 transcription factor. Loss-of-function ospsy8 mutants exhibited enhanced osmotic stress tolerance, whereas OsPSY8 overexpression increased osmotic stress susceptibility. Transcriptomic analyses revealed that disruption of OsPSY8 activated stress-responsive pathways, including those associated with lignin biosynthesis, compatible solute production, cell wall remodeling, and reactive oxygen species (ROS) scavenging, and was accompanied by increased lignin accumulation in roots. In contrast, overexpression of OsPSY8 resulted in maintenance of growth-associated transcriptional programs while suppressing stress-responsive pathways under osmotic stress. Together, these findings identify OsPSY8 as an important regulator of the transition from growth to stress adaptation in rice and suggest that stress-induced repression of PSY signaling is required to disengage growth programs and activate adaptive responses during osmotic stress. Significance StatementCrop survival during drought depends on the ability to transition from growth to stress adaptation. Plant peptide hormones have emerged as important regulators of this critical transition, highlighting the importance of investigating their roles and potential for improving crop resilience. We show that a rice peptide hormone regulates this transition. Under non-stress conditions, this peptide hormone, predominantly expressed in rice roots, promotes root growth while suppressing stress responses. During osmotic stress, expression of the peptide hormone decreases, resulting in activation of stress-responsive pathways, such as lignin biosynthesis and reactive oxygen species scavenging. These findings demonstrate that a peptide hormone coordinates the balance between growth and stress adaptation in rice, with broader implications for understanding and improving crop resilience.
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Claude Sonnet 4.6 · xhigh effort · 8 Nov 2026 · from the full text of version 1 (5 Aug 2026) · CC BY 4.0
Overexpressing rice peptide OsPSY8 lengthens roots but lowers osmotic stress survival, while knockout raises it; OsWRKY24 represses the OsPSY8 promoter and is induced by PEG.
Surviving drought requires switching from growth to stress adaptation, yet the roles of rice PSY peptides in stress responses were poorly understood. This work assigns OsPSY8 a growth-versus-stress regulatory role and identifies a transcription factor that represses it under osmotic stress.
Key results
ShownOsPSY5 and OsPSY8 are the main root-enriched OsPSY genes, nearly absent from leaves, and both are repressed by PEG osmotic stress, while most other family members are induced.
qRT-PCR of all eight OsPSY genes in 9-day-old Kitaake seedlings (n = 3 biological replicates); OsPSY5 and OsPSY8 expression fell as early as 2 h after PEG; pOsPSY8::GUS staining was weaker after PEG than in mock controls. · OsPSY5 and OsPSY8 are predominantly expressed in…; Figure legends
ShownOsPSY8 overexpression lowers survival of PEG stress, whereas knockout raises it. OsPSY5 overexpression did not change survival.
About 40 % of WT survived vs fewer than 10 % of OsPSY8-OX (two lines); KO1 and KO2 survival exceeded 60 % vs about 40 % in WT; electrolyte leakage differences were not significant; three OsPSY5-OX lines did not differ from WT. · Modulation of OsPSY8 expression altered osmotic…; Figure legends
SuggestedOsPSY8 overexpression lengthens roots, but loss of OsPSY8 does not shorten them. This is probably due to compensation by OsPSY5 and other family members.
ospsy8 mutants showed a nearly twofold increase in OsPSY5 expression; the ospsy5 ospsy8 double mutant still had longer roots than WT, with apparently reduced crown root formation. Data are mainly in supplementary figures. · OsPSY8 promotes root growth under non-stress…
SuggestedOsWRKY24 was prioritized from database screens as an OsPSY8 promoter repressor, with protoplast assays supporting repression. Its root transcript rose within 2 h of PEG, which the authors propose precedes the OsPSY8 decline.
OsWRKY24 was the only TF meeting all three criteria (PlantRegMap, PlantPAN 4.0, stele enrichment in scPlantDB). Dual-luciferase activity was reduced vs GFP control; ChIP-qPCR enrichment at W-box amplicons a and c (**P < 0.01 in legend). · OsWRKY24 directly binds to and represses the…; Figure legends
SuggestedOsPSY8 perturbation shifts root transcriptomes: knockout upregulates lignin, ROS scavenging and compatible-solute genes; overexpression keeps growth-associated genes active. Lignin content changes were mostly non-significant.
RNA-seq (3 replicates; WT, OX2, KO1) with |log2FC| > 1 and FDR ≤ 0.05: WT 3,607 and 3,108 DEGs at 0 h and 4 h; KO 139 and 335; OX 90 and 191. Post-stress lignin higher only in KO1 significantly. · OsPSY8 modulates growth- and stress-associated…; RNA-seq analysis; Figure legends
Methods, data and reproducibility
Expression profiling (qRT-PCR, GUS) and Ubi-driven overexpression plus CRISPR/Cas9 knockout rice lines were tested in PEG survival assays. Promoter regulation was probed with database mining, dual-luciferase and ChIP-qPCR, and mechanism with root RNA-seq and lignin quantification.
- qRT-PCR expression of eight OsPSY genes in leaves and roots, and PEG time course (0, 2, 4, 24 h), 9-day-old hydroponic seedlings · Oryza sativa ssp. Japonica cv. Kitaake · n = n = 3 biological replicates (3 plants each)
- PEG survival assays: two OsPSY8-OX lines (OX1, OX2) and two CRISPR alleles (ospsy8-1 KO1, ospsy8-2 KO2) · Oryza sativa (Kitaake) · n = n = 4 biological replicates (KO survival panel)
- Three OsPSY5-OX lines (5-OX1 to 5-OX3) and an ospsy5 knockout crossed to KO2 to make the ospsy5 ospsy8 double mutant · Oryza sativa (Kitaake)
- Root RNA-seq of WT, OX2 and KO1 before and 4 h after PEG · Oryza sativa (Kitaake) · n = 3 biological replicates per genotype and condition
- RiceENCODE root ATAC-seq (three open regions in 2.5-kb OsPSY8 promoter) and scPlantDB single-cell expression, used for TF prioritization · Oryza sativa
- Dual-luciferase and ChIP-qPCR in rice protoplasts testing OsWRKY24 on the OsPSY8 promoter · Oryza sativa
- Synthetic OsPSY8 peptide (500 nM) bioactivity test in the tpst mutant, and KO root rescue of OsCCR15 and OsGSTU36 · Arabidopsis (tpst); Oryza sativa (KO roots)
- Methods & tools
- qRT-PCR (normalized to OsUBQ5), CRISPRdirect, RiceENCODE, PlantRegMap, PlantPAN 4.0, scPlantDB, Dual-luciferase reporter assay, ChIP-qPCR, fastp v0.24.0, STAR v2.7.11, UMIcollapse v1.1.0, edgeR v4.0.16
- Reagents & environment
- fastp v0.24.0, STAR v2.7.11, UMIcollapse v1.1.0, featureCounts (subread v2.1.1), edgeR v4.0.16; transgenic lines advanced to at least the T2 generation.
- Reproducibility gaps
- No code repository, RNA-seq accession or URL for raw reads is given; DE results are in supplementary Datasets S1 to S5 and primers in Table S1, not in the main text.
Limitations (5)
- Only PEG-induced osmotic stress in hydroponics was used; performance in soil-drying, greenhouse or field conditions, and in other crops, remains untested. · stated by the authors
- Electrolyte leakage differences were not significant, and OsPSY8 peptide rescue of KO gene expression was partial. Lignin rose significantly only in KO1 after stress. · noted in this summary
- Constitutive Ubi promoter may cause ectopic effects, and OsPSY5 compensation or redundancy with other OsPSY genes complicates separating OsPSY5 from OsPSY8 functions. · stated by the authors
- OsWRKY24 overexpression or loss-of-function lines, stress-specific ChIP, and OsPSYR receptor-ligand interactions were not tested, so the pathway remains inferred. · stated by the authors
- RNA-seq used one OX line (OX2) and one KO allele (KO1) with three replicates; lignin and qPCR n were small, and the OsWRKY24 binding and repression were shown only in protoplasts. · noted in this summary
Who should read:Read this if you study peptide hormone signaling, root growth-stress trade-offs, or want a candidate gene and regulator for improving rice osmotic stress tolerance.
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