Yuhong Zhou

B-cell lymphoma 2 (Bcl-2)-associated athanogene (BAG) family proteins are co-chaperones that regulate growth, development, and cell death and are evolutionarily conserved across eukaryotes. The BAG gene family has attracted intense interest in human health research, but its plant counterparts have received little attention. In this study, we conducted a genome-wide scan of the BAG family in passion fruit, a crop of great economic importance. Fifteen PeBAG genes were identified, with all but PeBAG5 having multiple copies. PeBAG members, each characterized by a BAG domain, were categorized into two groups: Group 1 (PeBAG1/2/3/4) with extra ubiquitin domains, and Group 2 (PeBAG5/6-1/6-2) with additional plant-specific calmodulin-binding domains. The transcriptome data suggest that PeBAGs exhibit high gene expression in stems, flowers, and fruit, while PeBAG4-3 and 6-1 upregulated under hormonal and abiotic stresses. qRT-PCR further confirmed the heat stress activation of PeBAG4-3 and 6-1. Subcellular localization in planta revealed varied compartmentalization, with members in the nucleus, cytoplasm, and plastids demonstrating functional divergence. This study provides a guide for investigating and employing PeBAG genes to improve heat resistance in passion fruit.

Passion fruit is a valued tropical fruit crop that faces environment-related growth strains. TCP genes are important for both growth modulation and stress prevention in plants. Herein, we systematically analyzed the TCP gene family in passion fruit, recognizing 30 members. Genes exhibiting closer phylogenetic relationships exhibited similar protein and gene structures. Gene members of the TCP family showed developmental-stage- or tissue-specific expression profiles during the passion fruit life cycle. Transcriptome data also demonstrated that many PeTCPs showed induced expression in response to hormonal treatments and cold, heat, and salt stress. Based on transcriptomics data, eight candidate genes were chosen for preferential gene expression confirmation under cold stress conditions. The qRT-PCR assays suggested PeTCP15/16/17/19/23 upregulation, while PeTCP1/11/25 downregulation after cold stress. Additionally, TCP19/20/29/30 exhibited in silico binding with cold-stress-related miRNA319s. GFP subcellular localization assays exhibited PeTCP19/1 were localized at the nucleus. This study will aid in the establishment of novel germplasm, as well as the further investigation of the roles of PeTCPs and their cold stress resistance characteristics.