Small peptides (SPs) are pivotal signaling molecules that play essential roles in the precise regulation of plant growth, development, and stress responses. Recent advancements in sequencing technologies, bioinformatics approaches, and biochemical and molecular techniques have significantly enhanced the accuracy of SP identification, unveiling their diverse biological functions in plants. This review provides a comprehensive overview of the characteristics and methodologies for identifying SPs in plants. It highlights recent discoveries regarding the biological roles and signaling pathways of SPs in regulating plant growth, development, and plant–microbial interactions, as well as their contributions to plant resilience under various environmental stresses, including abiotic stress, nutrient deficiencies, and biotic challenges. Additionally, we discuss current insights into the potential applications of SPs and outline future research directions aimed at leveraging these molecules to enhance plant adaptation to environmental challenges. By integrating recent findings, this review lays a foundation for advancing the understanding and utilization of SPs to improve plant resilience and productivity.

Small peptides (SPs), ranging from 5 to 100 amino acids, play integral roles in plants due to their diverse functions. Despite their low abundance and small molecular weight, SPs intricately regulate critical aspects of plant life, including cell division, growth, differentiation, flowering, fruiting, maturation, and stress responses. As vital mediators of intercellular signaling, SPs have garnered significant attention in plant biology research. This comprehensive review delves into SPs’ structure, classification, and identification, providing a detailed understanding of their significance. Additionally, we summarize recent findings on the biological functions and signaling pathways of prominent SPs that regulate plant growth and development. This review also offers a perspective on future research directions in peptide signaling pathways.

The β-amylase (BAM) gene family encodes important enzymes that catalyze the conversion of starch to maltose in various biological processes of plants and play essential roles in regulating the growth and development of multiple plants. So far, BAMs have been extensively studied in Arabidopsis thaliana (A. thaliana). However, the characteristics of the BAM gene family in the crucial economic crop, cotton, have not been reported. In this study, 27 GhBAM genes in the genome of Gossypium hirsutum L (G. hirsutum) were identified by genome-wide identification, and they were divided into three groups according to sequence similarity and phylogenetic relationship. The gene structure, chromosome distribution, and collinearity of all GhBAM genes identified in the genome of G. hirsutum were analyzed. Further sequence alignment of the core domain of glucosyl hydrolase showed that all GhBAM family genes had the glycosyl hydrolase family 14 domain. We identified the BAM gene GhBAM7 and preliminarily investigated its function by transcriptional sequencing analysis, qRT-PCR, and subcellular localization. These results suggested that the GhBAM7 gene may influence fiber strength during fiber development. This systematic analysis provides new insight into the transcriptional characteristics of BAM genes in G. hirsutum. It may lay the foundation for further study of the function of these genes.

The development of stomatal lineage cells in terrestrial plants is tightly regulated by epidermal patterning factors (EPFs/EPFLs) and their downstream receptors, including ERECTA, TOO MANY MOUTHS (TMM), and SOMATIC EMBRYOGENESIS RECEPTOR KINASEs (SERKs). These components form co-receptor complexes that activate the MAPK signaling cascade, playing critical roles in stomatal development, stress responses, and signal transduction. However, the EPF–ERECTA–TMM signaling network remains largely unexplored in cotton (Gossypium spp.). In this study, we performed a genome-wide identification and characterization of the EPF/EPFL, ERECTA, TMM, and SERK gene families in four cotton species (G. hirsutum, G. barbadense, G. arboreum, and G. raimondii), identifying 135 EPF/EPFL, 18 ERECTA, 6 TMM, and 90 SERK genes. Bioinformatics analyses—including gene collinearity, protein domain structure, cis-regulatory elements, and protein–protein interaction predictions—revealed functional divergence and stress-related regulatory potential across these families. Expression profiling in G. hirsutum indicated that several candidate genes, such as GhEPFL1-1, GhER1, and GhSERK17, are responsive to abiotic stresses. To validate these computational predictions, functional assays were conducted. Virus-induced gene silencing (VIGS) of GhEPFL1-1, GhER1, and GhSERK17 led to increased stomatal density and reduced drought tolerance, confirming their roles in stress adaptation. Furthermore, luciferase complementation imaging in Nicotiana benthamiana demonstrated direct interactions between GhEPFL1-1 and GhER1, and co-receptor complex formation with GhSERK17, consistent with molecular docking simulations. Collectively, this study lays a theoretical foundation for further exploration of the EPF/EPFL-mediated peptide-receptor signaling pathway in cotton and its potential application in breeding for stress resilience.