Genome-Wide Identification of the Thaumatin-like Protein Family Genes in Gossypium barbadense and Analysis of Their Responses to Verticillium dahliae Infection

(1) Background: Plants respond to pathogen challenge by activating a defense system involving pathogenesis-related (PR) proteins. The PR-5 family includes thaumatin, thaumatin-like proteins (TLPs), and other related proteins. TLPs play an important role in response to biotic and abiotic stresses. Many TLP-encoding genes have been identified and functionally characterized in the model plant species. (2) Results: We identified a total of 90 TLP genes in the G. barbadense genome. They were phylogenetically classified into 10 subfamilies and distributed across 19 chromosomes and nine scaffolds. The genes were characterized by examining their exon–intron structures, promoter cis-elements, conserved domains, synteny and collinearity, gene family evolution, and gene duplications. Several TLP genes were predicted to be targets of miRNAs. Investigation of expression changes of 21 GbTLPs in a G. barbadense cultivar (Hai7124) resistance to Verticillium dahliae revealed 13 GbTLPs being upregulated in response to V. dahliae infection, suggesting a potential role of these GbTLP genes in disease response. (3) Conclusions: The results of this study allow insight into the GbTLP gene family, identify GbTLP genes responsive to V. dahliae infection, and provide candidate genes for future studies of their roles in disease resistance.