Abstract:
Cyclotides are small disulfide-rich proteins that h
ave the unusual feature of a cyclic
backbone. Cyclotides have a range of interesting bi
ological activities and are found in a
variety of tropical plants from the
Rubiaceae, Violaceae, Cucurbitaceae
and
Fabaceae
families. W
e have cloned and characterized cyclotides in
Viola modesta
, a
Viola
species
native to western Asia, which was collected from th
e Kurdistan Province of Iran. Fifteen
cyclotide sequences were obtained using homology ba
sed PCR strategy. Sequence analysis
showed that 14 of them had continued open reading f
rames and showed high level of
similarity to cyclotide
gene
s from other species of the
Violaceae
. After analyzing the full
endoplasmic reticulum signals of
V. modesta
cyclotides, two conserved sequences,
AAFALPA and ATAFALP, were detected. Analysis of iso
lated cyclotide sequences
showed that they all belonged to bracelet family an
d were separated into two subclasses.
Phylogenetic analysis of
cyclotide
genes from
V. modesta
and other
Viola
species revealed
that most
V. modesta
genes showed close relationship with their homologs
from the
Violaceae
, while the
V. modesta
genes formed two separate clades. Transcription ana
lysis
by semi-quantitative RT-PCR revealed that
Vmcyc1
and
Vmcyc7
were differentially
expressed in all tested tissues including roots, st
ems, leaves, flowers, seeds, peduncles, and
capsules with the highest transcript level in the c
apsules.
Keywords:
Bracelet cyclotides, Phylogeny, RT-PCR, Sequences,
3’RACE.
