Lulu Wang

ERF transcription factors matter greatly in plant development and stress responses. In this study, a total of 77 ERF genes were identified in the passion fruit genome. These genes were classified into 12 groups based on their phylogenetic tree and were further analyzed for their gene structure and conserved motifs. The results suggest that PeERF genes with close evolutionary relationships possess similar structural and motif compositions. The observation of the syntenic relationships revealed that both tandem and segmental duplication contributed to the expansion of ERF genes. Expression patterns of PeERFs across various organs and different developmental stages suggested diverse functional roles for these genes. In addition, differential expression patterns were observed under abiotic stress treatments, indicating a potential role for PeERFs in passion fruit adaptation to harsh environmental conditions. Notably, overexpression of PeERF68 consistently enhanced tolerance to salt and heat stress in Arabidopsis. These findings imply that PeERF genes may have important regulatory functions in plant growth and development. Overall, this work provides valuable insights for further research into the biological functions of PeERF genes in passion fruit.

The SQUAMOSA promoter binding proteins (SBPs) gene family plays important roles in plant growth and development. The SBP gene family has been identified and reported in many species, but it has not been well studied in passion fruit. In this study, a total of 14 SBP genes were identified in passion fruit and named from PeSBP1 to PeSBP14 based on their chromosomal distribution. The phylogenetic tree, gene structure, conserved motifs, collinearity analysis, and expression patterns of the identified SBP members were analyzed. We classified the PeSBP genes into eight groups (I to VIII) according to the phylogenetic tree, gene structure, and conserved motifs. Synteny analysis found that 5 homologous gene pairs existed in PeSBP genes and 11 orthologous gene pairs existed between passion fruit and Arabidopsis. Synonymous nucleotide substitution analysis showed that the PeSBP genes were under strong negative selection. The expression pattern of PeSBP genes in seed, root, leaf, and flower showed that nine of the PeSBP genes displayed high expression in the leaf and the flower. The expression patterns of PeSBP3/6/8/9/10 were further detected by qRT-PCR. In addition, differences in the expression levels occurred for each gene in the different flower organs and at the different developmental stages. There were large differences among SBPs based on transcriptional levels under cold, heat, salt, and osmotic stress conditions. Altogether, this study provides an overview of SBP genes in passion fruit and lays the foundation for further functional analysis.