Comprehensive Genome-Wide Identification and Expression Profiling of () Gene Family in Passion Fruit () Under and Drought Stress Conditions.

Plant surfaces are covered with cuticle wax and are the first barrier between a plant and environmental stresses. () is an important gene family involved in wax biosynthesis and stress resistance. In this study, for the first time, 34 genes were identified in the passion fruit () genome, and PeCER proteins varied in physicochemical properties. A phylogenetic tree was constructed and divided into seven clades to identify the evolutionary relationship with other plant species. Gene structure analyses revealed that conserved motifs ranged from 1 to 24, and that exons ranged from 1 to 29. The -element analysis provides insight into possible roles of genes in plant growth, development and stress responses. The syntenic analysis revealed that segmental (six gene pairs) and tandem (six gene pairs) gene duplication played an important role in the expansion of genes and underwent a strong purifying selection. In addition, 12 putative ped-miRNAs were identified to be targeting 16 genes, and was the most targeted by four miRNAs including ped-miR157a-5p, ped-miR164b-5p, ped-miR319b, and ped-miR319l. Potential transcription factors (TFs) such as ERF, AP2, MYB, and bZIP were predicted and visualized in a TF regulatory network interacting with genes. GO and KEGG annotation analysis revealed that genes were highly related to fatty acid, cutin, and wax biosynthesis, plant-pathogen interactions, and stress response pathways. The hypothesis that most PeCER proteins were predicted to localize to the plasma membrane was validated by transient expression assays of PeCER32 protein in onion epidermal cells. qRT-PCR expression results showed that most of the genes including , and were upregulated under drought and stress conditions compared to controls. These findings provide a foundation for further studies on functions of genes to further facilitate the genetic modification of passion fruit wax biosynthesis and stress resistance.