CAP peptides: A Novel plant biostimulant that enhances plant growth and multi-stress tolerance via priming

Recent climate change has severely threatened crop yields worldwide. To address this problem, we evaluated CAP peptides, a novel peptide biostimulant containing a conserved six-amino-acid core (F/Y-T-Q-I/V-V-W) derived from the CAP superfamily proteins. We demonstrate that low-concentration (60 nM) application of the CAP-p22 peptide significantly upregulates photosynthesis-related genes, stress-responsive genes, and the morning complex of the circadian clock genes in Arabidopsis thaliana. In fact, CAP peptides at low concentrations not only promote primary root growth, lateral root formation, and chlorophyll accumulation, but also confer robust tolerance to multiple environmental challenges, including salt stress, lethal heat stress, and nitrate deficiency. Furthermore, beyond abiotic factors, these peptides enhance resistance to both fungal (Alternaria brassicicola) and bacterial (Pseudomonas syringae pv. tomato DC3000) pathogens. Most importantly, we show that CAP peptides achieve this dual efficacy—promoting growth while enhancing stress resilience—through a priming mechanism that enables a rapid molecular response to stressors without the typical energy trade-off. The practical utility of CAP peptides was validated in food crops, showing significant growth enhancement in rice (Oryza sativa) and Japanese mustard spinach (Brassica rapa), as well as restoring germination rates in aged Arabidopsis seeds. Our results suggest that CAP peptides represent a high-safety, low-dose, and scientifically validated tool for sustainable agriculture.