Pyrophosphate-dependent phosphofructokinase
(PFP) catalyses the reversible phosphorylation of fructose-6-
phosphate to fructose-1,6-bisphosphate in the glycolysis pathway.
Two full-length complementary DNAs encoding putative
PFP α- and β-subunits, named EjPFPa and EjPFPb1,
were isolated by reverse transcription polymerase chain reaction
(RT-PCR) and rapid amplification of the cDNA ends
(RACE) from Eriobotrya japonica Lindl. (loquat). The other
β-subunit gene was identified from transcriptome data obtained
by Illumina sequencing, designated as EjPFPb2. They
share up to 88 % identity with other plant PFP α/β-subunits.
EjPFPa and EjPFPb clustered separately in clades of plant
PFP α- or β-subunits, respectiv... More
Pyrophosphate-dependent phosphofructokinase
(PFP) catalyses the reversible phosphorylation of fructose-6-
phosphate to fructose-1,6-bisphosphate in the glycolysis pathway.
Two full-length complementary DNAs encoding putative
PFP α- and β-subunits, named EjPFPa and EjPFPb1,
were isolated by reverse transcription polymerase chain reaction
(RT-PCR) and rapid amplification of the cDNA ends
(RACE) from Eriobotrya japonica Lindl. (loquat). The other
β-subunit gene was identified from transcriptome data obtained
by Illumina sequencing, designated as EjPFPb2. They
share up to 88 % identity with other plant PFP α/β-subunits.
EjPFPa and EjPFPb clustered separately in clades of plant
PFP α- or β-subunits, respectively. EjPFPa and EjPFPb were
both shown to be mainly localised in the cell membrane using
confocal microscopy of GFP fusion proteins 35S:EjPFPa/bGFP.
Monitoring the dynamic changes of transcripts and
proteins demonstrated that EjPFPa and EjPFPb did not show
coordinated expression during fruit development in loquat.
The transcript levels of EjPFPa and EjPFPb in the leaves of
loquat seedlings were significantly enhanced after 3 h of
treatment with 0.5, 1.0 and 1.5 M fructose or glucose, which
indicates that EjPFPa and EjPFPb are modulated by fructose
and glucose in vivo. Transgenic tobacco plants overexpressed
EjPFPa did not show visible phenotype changes, while plants
overexpressing EjPFPb1 grew faster at the cost of reduced
leaf size and sucrose content. Meanwhile, fructose content
increased in growing plants compared with wild-type plants.
The results confirm that genes of the two subunits from loquat
PFP have different transcriptional regulation systems and play
different roles in carbohydrate metabolism. Elevation of the
PFP β-subunit gene expression can partly impact the glycolytic
carbon allocation in growing plants.