TCP Transcription Factors in Pineapple: Genome-Wide Characterization and Expression Profile Analysis during Flower and Fruit Development

Abstract

TEOSINTE-BRANCHED1/CYCLOIDEA/PCF (TCP) transcription factors contain specific a basic helix–loop–helix structure, which is a significant factor in the regulation of plant growth and development. TCP has been studied in several species, but no pineapple TCP has been reported to date. Whether they are involved in the development of the flower and fruit in the pineapple remains unclear. In this study, nine non-redundant pineapple TCPs (AcTCPs) were identified. Chromosomal localization, phylogenetics, gene structure, motifs, multiple-sequence alignment, and covariance on AcTCP family members were analyzed. Analysis of promoter cis-acting elements illustrated that the AcTCP gene may be mainly co-regulated by light signal and multiple hormone signals. Analysis of expression characteristics showed a significant increase in AcTCP5 expression at 12 h after ethylene treatment, and significantly higher levels of AcTCP8 and AcTCP9 expression in the pistil than in other floral organs. Meanwhile, the AcTCP4, AcTCP5, AcTCP6, AcTCP7, and AcTCP9 expression levels were downregulated at later stages of fruit development. Transcription factors that may interact with TCP protein in the regulation of flower and fruit development are screened by the protein interaction prediction network, AcTCP5 interacts with AcSPL16, and AcTCP8 interacts with AcFT5 and AcFT6 proteins, verified by Y2H experiments. These findings provide a basis for further exploration of the molecular mechanisms and function of the AcTCP gene in flower and fruit development.