Peptide Signaling in Flowering Plants: Insights into Reproductive Thermotolerance.

Flowering plants use small, secreted peptides to initiate complex signaling cascades that coordinate essential developmental processes and facilitate adaptation to environmental stresses. During plant reproduction, precise cell-cell interactions form the foundation of a tightly coordinated transition from sporophytic to gametophytic generation, culminating in pollen germination, tip growth, gamete fusion, and seed and fruit formation. While these reproductive processes have been studied from developmental and functional perspectives, emerging questions center on their vulnerability to rising global temperatures and heat-induced stress. By integrating insights from both research areas, this review comprehensively explores the diverse roles of small signaling peptides in plant reproduction and abiotic stress responses. While peptides are known regulators of reproductive developmental signaling, relatively few have been characterized for their roles in abiotic stress responses of reproductive tissues. To address this knowledge gap, we performed a meta-analysis of publicly available RNA-Seq data in reproductive tissues to identify candidate peptides in reproductive function and stress resilience. Our analysis highlights the altered expression of CLE and RALF gene families, identifying potential candidates for reproductive thermotolerance. Given their synthetic accessibility and ability to act when applied exogenously, small peptides present a promising avenue to enhance reproductive success and abiotic stress tolerance. These insights provide a framework for future functional studies and the development of targeted strategies to improve crop reproductive thermotolerance, offering a pathway to sustaining crop productivity under climate change.