Identification and characterisation of a novel FT orthologous gene in London plane with a distinct expression response to environmental stimuli compared to PaFT

Abstract

FLOWERING LOCUS T (FT) is a key integrator of environmental signals and internal cues, and codes for florigen-like activity which regulates the transition from vegetative to reproductive growth in flowering plants. Unlike annual plants, perennial tree species undergo several years of vegetative growth prior to the transition to the reproductive stage, as characterised by the ability to form flower buds. Thereafter, trees in temperate regions typically display an annual growth cycle involving distinct vegetative growth, flowering and dormancy stages.• In London plane (Platanus acerifolia Willd.), a FT-like gene has previously been identified. Here, we report the isolation of a novel FT orthologous gene, PaFTL, and investigate the functions of PaFT and PaFTL through the analysis of expression profiles and transgenic phenotypes.• PaFT displayed the highest levels of expression during tree dormancy, and similarly elevated expression levels were seen under conditions of low temperature and short days (LT/SD). In contrast, PaFTL transcripts were up-regulated during the floral transition phase, the early stages of inflorescence development and throughout the main flowering period, whereas expression levels were low and variable during dormancy and in response to LT/SD treatments. Ectopic expression of 35s::PaFTL in tobacco produced a phenotype similar to that with PaFT, namely, advanced floral initiation.• Overall, the results suggest that PaFT and PaFTL have both conserved and diverse functions in floral initiation, floral development and dormancy regulation.

Genome-Wide Analysis of the BBX Genes in Platanus × acerifolia and Their Relationship with Flowering and/or Dormancy

“…In addition, some PaBBX genes were regularly expressed, corresponding to different stages of dormancy and bud break. Previous studies have shown that the expression of PaFT dramatically increased under low temperatures and short days from early autumn to late winter and was believed to serve to release buds from dormancy [27]. Expression patterns of PaBBX8-1, PaBBX8-2, PaBBX9-1, PaBBX28/29-1, and PaBBX32-2 were similar to these of PaFT, suggesting that these genes may act as an upstream regulator of PaFT to contribute to the break of dormancy.…”

“…Platanus × acerifolia is a perennial deciduous tree undergoing a flowering transition in mid to late spring. This is followed by vegetative growth in summer, then enters dormancy in early autumn to late winter, and subpetiolar bud breaks in early spring [27,28]. Previous studies have revealed that two FT orthologs, which may act as downstream targets of BBX homologous genes, are responsible for regulating flowering and/or dormancy in P. × acerifolia, respectively [27,29,30].…”

“…This is followed by vegetative growth in summer, then enters dormancy in early autumn to late winter, and subpetiolar bud breaks in early spring [27,28]. Previous studies have revealed that two FT orthologs, which may act as downstream targets of BBX homologous genes, are responsible for regulating flowering and/or dormancy in P. × acerifolia, respectively [27,29,30]. In this study, we performed the first genomewide and transcriptome analysis of the BBX gene family of P. × acerifolia.…”

Integrated transcriptome and proteome analysis provides insight into chilling-induced dormancy breaking in Chimonanthus praecox

“…By comparison, PaFT has been shown to display increased expression levels in response to LT/SD in London plane trees 43 . Moreover, PaFTL, another FT orthologous gene in London plane trees, showed low and variable expression levels during dormancy and under LT/SD conditions 44 .…”