Plant tetraspanins: dynamic membrane players for bolstering crop stress resilience

Tetraspanins (TETs) are a conserved family of integral membrane proteins defined by a core architecture of four transmembrane domains, a small extracellular loop, and a larger extracellular loop that harbors conserved cysteine residues essential for intramolecular disulfide bonding and protein-protein interactions. In plants, the extracellular 2 (EC2) domain uniquely features a signature 'GCCK/RP' motif which may contribute to species-specific structural configurations and functional specializations. As essential components of cellular architecture, TETs also organize dynamic membrane complexes known as 'tetraspanin-enriched microdomains' (TEMs) or tetraspanin webs, which house a multitude of protein partners. Recent studies highlight the crucial roles of TETs in various plant functions such as development (root and leaf patterning, floral and seed development, and senescence), abiotic stress responses (drought, cold, and salt tolerance), defense mechanisms (immunity against fungal infestation), and cross-kingdom communication (facilitation of viral entry, symbiotic relationships of plants with arbuscular mycorrhizae or rhizobium). Molecular evidence suggests that TETs orchestrate these vital processes by modulating signal transduction pathways, maintaining hormone balance, cargo trafficking, and reactive oxygen species (ROS) homeostasis. Investigating the intricate biological functions and molecular actions of TETs opens promising avenues for fine-tuning the plant architecture, improving crop resilience to abiotic stresses, and fortifying defense against pests and diseases. This review unveils the recent advancements in our understanding of plant TETs and examines strategies to exploit their potential for boosting agricultural productivity and sustainability.