Intramolecular disulfide bonds can modulate overall peptide rigidity and improve structural stability, thereby serving as essential post-translational modifications for signaling small secreted peptides (SSPs). Despite the widespread distribution of signaling SSPs with a single intramolecular disulfide bond, such as oxytocin, urotensin Ⅱ, vasopressin, and somatostatin in animals, few analogous SSPs have been characterized in plants (Daly and Wilson, 2021). To date, only delta-like phytocytokines (DEPs) (Wang et al., 2025) have been functionally characterized as such SSPs in plants. SMALL PHYTOCYTOKINES REGULATING DEFENSE AND WATER LOSS (SCREW) (Liu et al., 2022)/CTNIPs (Rhodes et al., 2022) are phytocytokines that activate immune responses (e.g., mitogen-activated protein kinase [MAPK] phosphorylation) and regulate stomatal closure through PLANT SCREW UNRESPONSIVE RECEPTOR (NUT)/HAESA-LIKE 3 (HSL3), which belongs to the leucine-rich repeat receptor-like kinase (LRR-RLK) XI subfamily. SCREW peptides activate NUT by promoting its heterodimerization with BRASSINOSTEROID INSENSITIVE 1-ASSOCIATED KINASE 1 (BAK1) (Liu et al., 2022). However, whether the biological function of SCREW2 depends on conformational changes induced by its disulfide bond and the underlying mechanisms governing the assembly of NUT–SCREW–BAK1 complexes remain elusive.