Postharvest
Biology
and
Technology
85
(2013)
89–93
Contents
lists
available
at
ScienceDirect
Postharvest
Biology
and
Technology
jou
rn
al
h
om
epage:
www.elsevier.com/locate/postharvbio
The
effects
of
ethylene,
1-MCP
and
AVG
on
sprouting
in
sweetpotato
roots
M.U.A.
Cheema
a
,
D.
Rees
a,∗
,
R.J.
Colgan
a
,
M.
Taylor
b
,
A.
Westby
a
a
Natural
Resources
Institute,
University
of
Greenwich,
Chatham
Maritime,
Kent
ME4
4TB,
England,
United
Kingdom
b
The
James
Hutton
Institute,
Invergowrie,
Dundee
DD2
5DA,
Scotland,
United
Kingdom
a
r
t
i
c
l
e
i
n
f
o
Article
history:
Received
17
November
2012
Accepted
2
May
2013
Keywords:
Sweetpotato
1-Methylcyclopropene
Aminoethoxyvinylglycine
Ethylene
Respiration
Sprouting
a
b
s
t
r
a
c
t
Exogenous
ethylene
is
commonly
used
as
a
commercial
sprouting
inhibitor
of
potato
tubers.
The
role
of
ethylene
in
the
control
of
sprouting
of
sweetpotato
roots,
however,
is
not
known.
The
aim
of
this
study
was
to
investigate
the
role
of
ethylene
in
control
of
sprouting
in
sweetpotato
roots
by
observing
the
effect
of
an
ethylene
synthesis
inhibitor,
aminoethoxyvinylglycine
(AVG),
and
the
ethylene
antagonist,
1-methylcyclopropene
(1-MCP),
in
the
presence
and
absence
of
exogenous
ethylene
on
root
sprouting
and
associated
sugar
accumulation.
Continuous
exposure
to
10
l
L
−1
ethylene,
24
h
exposure
to
625
nl
L
−1
1-MCP
or
dipping
in
100
l
L
−1
AVG
all
inhibited
sprout
growth
in
sweetpotato
roots
of
two
varieties
over
4
weeks
of
storage
at
25
◦
C.
The
observations
that
both
ethylene
on
its
own
and
1-MCP,
which
inhibits
ethylene
action,
inhibit
sprout
growth
indicate
that
while
continuous
exposure
to
exogenous
ethylene
leads
to
sprout
growth
inhibition,
ethylene
is
also
required
for
sprouting.
In
potato
tubers
ethylene
is
required
to
break
dormancy,
while
continuous
exposure
inhibits
sprout
growth.
Monosaccharide
concentrations
in
ethylene,
1-MCP
or
AVG
treated
roots
were
lower
than
in
untreated
roots,
and
for
ethylene
treated
roots
this
was
associated
with
higher
respiration
rates.
This
is
consistent
with
the
activation
of
some
additional
process
by
ethylene
which
uses
energy
through
sugar
metabolism.
1-MCP
and
AVG
both
inhibited
this
increase
in
respiration
rate
and
counteracted
the
decrease
in
monosac-
charide
concentrations.
1-MCP
presumably
counteracts
the
ethylene
stimulation
of
this
process,
while
the
effect
of
AVG
is
attributed
to
its
possible
inhibitory
effects
on
protein
synthesis.
©
2013
Elsevier
B.V.
All
rights
reserved.
1.
Introduction
Ethylene
is
a
plant
hormone
with
a
wide
range
of
physiologi-
cal
effects
depending
on
the
state
of
the
plant
tissues
it
is
acting
on.
In
the
case
of
potatoes,
initially
it
was
reported
that
con-
tinuous
ethylene
extended
tuber
dormancy
(Prange
et
al.,
1998),
but
more
recent
studies
indicate
that
ethylene
inhibits
sprout
growth
while
promoting
dormancy
break
(Prange
et
al.,
2005).
Information
on
sprout
control
in
sweetpotato
storage
roots
is
much
more
limited,
and
the
effects
of
endogenous
ethylene
remain
to
be
fully
detailed.
It
has
been
reported
that
isopropyl
N-(3-
chlorophenyl)
carbamate
(CIPC)
(Kushman
and
Wrights,
1969),
naphthalene
acetic
acid
(Paton
and
Scriven,
1989)
and
gamma
irradiation
(Bonsi
and
Loretan,
1988)
all
suppress
sprouting
to
some
degree
in
sweetpotato
roots.
Continuous
ethylene
applica-
tion
(10
l
L
−1
)
suppresses
sprouting
in
sweetpotatoes
effectively
during
storage
for
4
weeks
at
25
◦
C
(Cheema
et
al.,
2010).
∗
Corresponding
author.
Tel.:
+44
1634
883522;
fax:
+44
1634
883386.
E-mail
addresses:
m.u.a.cheema@gre.ac.uk
(M.U.A.
Cheema),
d.rees@gre.ac.uk
(D.
Rees),
r.j.colgan@gre.ac.uk
(R.J.
Colgan),
mark.taylor@hutton.ac.uk
(M.
Taylor),
a.westby@gre.ac.uk
(A.
Westby).
Ethylene
perception
can
be
blocked
using
1-
methylcyclopropene
(1-MCP),
which
binds
to
ethylene
receptors,
preventing
ethylene
from
exerting
its
effects
(Blankenship
and
Dole,
2003).
1-MCP
is
approved
for
food
use
in
several
countries,
and
has
been
tested
on
a
range
of
climacteric
and
non-climacteric
fresh
fruit,
vegetables
and
cut
flowers
(Watkins
and
Miller,
2005;
Watkins,
2006).
1-MCP
has
been
reported
to
reduce
ethylene
induced
effects,
including
senescence,
in
a
variety
of
potted
flow-
ering
plants
and
cut
flowers
(Serek
et
al.,
1995,
1996;
Sisler
et
al.,
1996;
Heyes
and
Johnson,
1998;
Newman
et
al.,
1998).
Effects
of
1-MCP
on
fruit
and
vegetables
include
inhibition
of
ripening
of
apples
(Fan
and
Mattheis,
1999;
Watkins
et
al.,
2000;
DeEll
et
al.,
2002
),
pears
(Wild
et
al.,
1999;
Baritelle
et
al.,
2001),
stonefruit
(
Fan
et
al.,
2000;
Blankenship
and
Parker,
2001),
bananas
(Harris
et
al.,
2000)
and
other
tropical
fruit
(Selvarajah
et
al.,
2001;
Ergun
and
Huber,
2004).
1-MCP
is
used
commercially,
especially
during
apple
storage,
in
which
case
it
can
extend
storage
life
as
well
as
preventing
some
physiological
disorders
such
as
superficial
scald
development
(Watkins
et
al.,
2000;
Calvo
and
Candan,
2001;
Solomos
et
al.,
2001).
1-Aminoethoxyvinylglycine
(AVG),
the
active
ingredient
in
ReTain
®
(Valent
Biosciences
Corporation,
USA),
is
a
plant
growth
regulator
that
inhibits
1-aminocyclopropane-1-carboxylate
0925-5214/$
–
see
front
matter
©
2013
Elsevier
B.V.
All
rights
reserved.
http://dx.doi.org/10.1016/j.postharvbio.2013.05.001