Genome-Wide Identification and Bioinformatics Analysis of Thaumatin-like Proteins in Aegiceras corniculatum

Background: The mangrove ecosystem serves as a vital coastal ecotone, providing essential ecological services, such as water purification, shoreline protection, and biodiversity maintenance. Fungal pathogens threaten mangrove health and contribute to ecosystem degradation, but the molecular mechanisms underlying disease resistance in mangroves remain poorly explored. Introdustion: Thaumatin-like proteins (TLPs), belonging to the pathogenesis-related-5 (PR-5) family, play a crucial role in antifungal defense in plants. Method and results: In this study, we identified 23 TLP family members in the mangrove Aegiceras corniculatum. The genes encoding TLP family members were unevenly distributed on chromosomes. Collinearity analyses showed that TLP family members in A. corniculatum underwent multiple gene duplication events, and Ka/Ks calculations revealed that these duplicated genes were predominantly under purifying selection. Among the 23 TLPs, AcTLP19 was significantly upregulated after Botrytis cinerea infection. Subcellular localization prediction and experiments revealed the extracellular localization of AcTLP19. Conclusions: Heterologous expression and antibacterial tests showed that recombinant AcTLP19 had no direct antifungal activity against B. cinerea or Fusarium oxysporum under the tested conditions, leaving open the possibility that it contributes to mangrove defense through indirect mechanisms, or that its antifungal activity was not captured under the specific assay conditions. This study advances our knowledge of mangrove stress responses and may contribute to future conservation strategies.