From Lipid Shuttling to Signaling Hubs: The Multifaceted Roles of Non-Specific Lipid Transfer Proteins in Plant Adaptation

Non-specific lipid transfer proteins (nsLTPs) are small cysteine-rich proteins belonging to the cysteine-rich peptide (CRP) antimicrobial peptide superfamily, widely distributed across land plants and involved in key physiological processes including fertilization, cell wall organization, wax deposition, and responses to biotic and abiotic stresses. Recent genomic and evolutionary analyses have revealed an extensive diversification of nsLTPs across plant lineages, which has led to multiple classification systems based on molecular mass, cysteine spacing, intron structure, and GPI (glycosylphosphatidylinositol-anchored proteins)-anchor motifs. This diversity reflects their adaptive expansion during plant terrestrialization. This review proposes that nsLTPs act as central nodes connecting lipid metabolism, developmental signals, and stress response networks, functioning as integrative signaling hubs rather than simple lipid carriers. Building on this central thesis, we synthesize current knowledge on nsLTP structure, classification, and evolution, and examine their multifaceted roles in plant development and defense. We also highlight emerging biotechnological applications and identify key gaps that warrant further investigation.