ArticlePDF Available

Epinasty of Poinsettias--the Role of Auxin and Ethylene

Authors:

Abstract and Figures

Upward physical restraint of the normally horizontal bracts of poinsettia (Euphorbia pulcherrima Willd.) resulted in increased ethylene production and epinastic curvature of the petioles after 5 days. Downward restraint caused little change in ethylene production or epinasty, indicating that the enhanced ethylene production observed in petioles bent upwards is not due to the bending stress alone. Epinasty, measured upon removal of upward physical restraint, was not affected by spraying plants with aminoxyacetic acid to reduce ethylene production or with silver thiosulfate to prevent ethylene action. Removal of the bract blades prevented the epinastic response of the petiole, and the response was restored by applying indoleacetic acid to the cut petiole end. Redistribution of auxin appears to be responsible for both the epinasty and the increased ethylene production of reoriented poinsettia bracts.
Content may be subject to copyright.
Plant
Physiol.
(1981)
67,
950-952
0032-0889/81/67/0950/03/$00.50/0
Epinasty
of
Poinsettias-the
Role
of
Auxin
and
Ethylene
Received
for
publication
December
3,
1979
and
in
revised
form
October
28,
1980
MICHAEL
S.
REID,
YORAM
MOR',
AND
ANTON
M.
KOFRANEK
Department
of
Environmental
Horticulture,
University
of
California,
Davis,
California
95616
ABSTRACT
Upward
physical
restraint
of
the
normally
horizontal
bracts
of
poinsettia
(Euphorbia
puadherrima
Wild.)
resulted
in
increased
ethylene
production
and
epinastic
curvature
of
the
petioles
after
5
days.
Downward
restraint
caused
Uttle
change
in
ethylene
production
or
epinasty,
indicating
that
the
enhanced
ethylene
production
observed
in
petioles
bent
upwards
is
not
due
to
the
bending
stress
alone.
Epinasty,
measured
upon
removal
of
upward
physical
restraint,
was
not
affected
by
spraying
plants
with
aminoxyacetic
acid
to
reduce
ethylene
production
or
with
silver
thiosulfate
to
prevent
ethylene
action.
Removal
of
the
bract
blades
prevented
the
epinastic
response
of
the
petiole,
and
the
response
was
restored
by
applying
indole-
acetic
acid
to
the
cut
petiole
end.
Redistribution
of
auxin
appears
to
be
responsible
for
both
the
epinasty
and
the
increased
ethylene
production
of
reoriented
poinsettia
bracts.
Upward
vertical
reorientation
of
the
normally
horizontal
bracts
of
poinsettia
plants
causes
drooping
of
the
bracts
upon
removal
of
the
force
holding
the
bract
in
a
vertical
position
(16).
It
has
recently
been
concluded
by
several
workers
that
an
endogenous
production
of
C2H4
in
response
to
the
bending
stress
during
reorientation
causes
this
epinastic
reponse
(13,
15).
This
conclusion
was
based
on
a
correlation
between
C2H4
production
by
petioles
and
the
epinastic
response
(14),
the
partial
reduction
of
the
effect
by
treatment
with
silver
nitrate
and
the
known
epinastic
response
of
poinsettia
to
exogenous
C2H4
(15).
Although
most
of
the
data
reported
thus
far
are
consistent
with
the
view
that
the
bending
stress
during
reorientation
induces
production
of
C2H4,
which
in
turn
causes
epinasty
by
altering
the
pattern
of
auxin
distribution
(1
1),
this
hypothesis
has
not
yet
been
proved.
An
alternative
hypothesis,
namely
that
the
change
in
orientation
itself
brings
about
a
redistribution
of
auxin
in
the
petiole,
which
not
only
causes
the
epinasty
but
also
enhances
C2H4
production
by
the
petioles
can
be
supported
by
the
following
observations:
Poinsettia
and
other
plants
become
epinastic
in
the
absence
of
stress
if
they
are
rotated
on
a
clinostat;
this
epinasty
is
associated
with
a
changed
distribution
of
auxin
in
the
petioles
(10).
C2H4
production
increases
in
plants
rotated
on
a
clinostat
(8).
Position-induced
epinasty
cannot
be
overcome
by
hypobaric
reduction
of
02
and
C2H4
concentrations
(17).
Ag+,
a
potent
inhibitor
of
the
epinasty
caused
by
applied
C2H4
in
tomatoes
(2,
3),
is
only
partly
able
to
reduce
position-induced
epinasty
in
poinsettia
(15).
The
purpose
of
the
study
reported
here
was
to
evaluate
the
relative
importance
of
C2H4
and
auxin
in
the
epinasty
of
reoriented
poinsettia
bracts.
1
On
leave
from
the
Department
of
Ornamental
Horticulture,
The
Hebrew
University
of
Jersualem,
Rehovot,
Israel.
MATERIALS
AND
METHODS
Poinsettia
plants
(Euphorbia
pulcherrima
Willd.,
'Annette
Hegg
Diva')
were
grown
in
a
greenhouse
under
standard
cultural
con-
ditions
(7)
until
they
reached
anthesis.
The
plants
were
pinched
to
give
four
flowering
branches
each.
The
large
colored
bracts
were
vertically
oriented
by
bending
them
upwards
or
downwards
against
the
stem
and
holding
them
in
this
position
with
rubber
bands.
The
plants
were
then
held
in
a
dark
growth
chamber
at
a
constant
temperature
of
15.5
C
for
5
days.
After
this
time,
the
rubber
bands
were
removed
and
the
large
colored
bracts
were
immediately
excised
and
debladed.
Epinasty
was
recorded
by
placing
the
excised
petioles
on
a
photocopier
and
making
a
copy.
The
angle
between
tangents
to
the
curve
at
each
end
of
the
petiole
was
then
measured
(Fig.
1).
For
determination
of
C2H4
production,
petioles
from
each
rep-
lication
were
weighed
and
placed
in
55-ml
tubes,
sealed
with
serum
caps.
After
3
h,
a
3-ml
sample
was
withdrawn
by
means
of
a
gas-tight
syringe
and
the
C2H4
production
by
the
petioles
in
the
tube
was
determined
using
a
"Carle"
gas
chromatograph
equipped
with
an
"HNU"
photoionization
detector
and
a
"Keithley"
614C
electrometer.
Plants
were
treated
with
C2H4
gas
by
placing
them
for
24
h
in
sealed
glass
tanks
(two
plants
per
tank)
ventilated
with
40
1/h
of
air
containing
15
,Il/l
of
C2H4.
AOA2
was
used
as
an
inhibitor
of
C2H4
production
(20)
and
was
dissolved
in
DI
to
final
concentrations
of
2
and
5
mM;
plants
were
sprayed
to
run-off
2
h
before
reorientation.
When
petioles
were
to
be
pretreated
with
IAA,
the
bract
blades
were
removed,
and
IAA
was
applied
at
a
concentration
of
1%
in
lanolin
paste,
either
to
the
cut
stump
or
to
the
adaxial
surface
of
the
petiole.
The
petioles
were
then
reoriented
as
described
before.
STS
was
used
to
study
the
effects
of
an
antagonist
of
C2H4
action
(18)
in
normal
and
debladed
petioles,
with
and
without
applied
IAA.
It
was
prepared
by
mixing
one
part
of
0.1
M
AgNO3
with
four
parts
of
0.1
M
Na2S203
and
diluting
with
DI
to
a
final
Ag+
concentration
of
4
mm
(12).
RESULTS
Effects
of
Reorientation
and
Inhibition
of
C2H4
Production.
Upward
vertical
restraint
caused
epinasty
(Fig.
1)
and
increased
C2H4
production
in
the
petioles
of
poinsettia
plants
post-restraint
(Tables
I
and
II).
In
contrast,
C2H4
production
post-restraint
was
unaffected
when
the
petioles
were
restrained
vertically
down-
wards,
although
this
caused
a
slight,
but
significant,
epinasty
(Table
I).
C2H4
production
post-restraint
by
the
upward
vertically
oriented
petioles
of
plants
pretreated
with
5
mm
AOA
was
the
same
as
in
petioles
of
control
plants
oriented
horizontally
(Table
II).
The
AOA
pretreatment
did
not
prevent
the
epinasty
of
reoriented
petioles.
Effects
of
the
Blades,
of
IAA
and
of
STS.
When
the
blades
of
2Abbreviations:
AOA,
aminoxyacetic
acid;
DI,
deionized
water;
STS,
silver
thiosulfate.
950
POINSETTIA
EPINASTY
_
_s
!__
_
> s
/
-_
.
_
X
_-;j
J
/t
e
/
_bf
^
_
_
_
__
_______
,
_
_
_
_
_
_
_
--
_
-
S
-
--_
/'
/
____~~~~/
f/
I
~
-
--
m
_
_-~~~~~~~
___-_f
-
b
FIG.
1.
Method
for
determining
epinastic
curvature.
Petioles
from
con-
trol
(a)
and
reoriented
(b)
bracts
were
excised
and
copied
in
a
photocopier.
The
angle
between
tangents
to
the
curvature
of
the
ends
of
the
petioles
(6f)
was
used
as
a
measure
of
epinasty.
Table
I.
Effect
of
Reorientation
on
Post-restraint
Epinastic
Curvature
and
C2H4
Production
by
Poinsettia
Petioles
Means
of
four
stems
(averaging
six
petioles
each)
per
treatment.
Means
in
each
column
with
no
letter
in
common
are
significantly
different
(P
=
0.05,
Duncan's
Multiple
Range
Test).
Orientation
Epinastic
C2H4
production
angle
degrees
nl/g
h
Horizontal
3c
0.62a
Vertical
(upwards)
39a
l.67b
Vertical
(downwards)
18b
0.65a
Table
II.
Post-restraint
C2H4
Production
and
Epinastic
Angle
of
Petioles
from
Poinsettia
Plants
Sprayed
2
Hours
before
Reorientation
with
Various
Concentrations
of
A
OA
Means
of
five
branches,
six
petioles
per
branch.
Means
for
each
param-
eter
with
no
subscript
letter
in
common
are
significantly
different
(P
=
0.05,
Duncan's
Multiple
Range
Test).
AOA
Horizontal
Vertical
tration
C2H4
produc-
Epinastic
C2H4
produc-
Epinastic
tion
angle
tion
angle
mM
nl/g.h
degrees
nl/g-h
degrees
0
0.22c
1lc
0.86b
46a
2
0.08c
8c
0.62b
44a
5
0.00c
9c
0.27c
40a
poinsettia
bracts
were
removed
before
reorientation
of
the
petioles,
the
normal
epinastic
curvature
did
not
occur,
although
post-re-
straint
C2H4
production
by
the
petioles
was
similar
to
that
of
petioles
from
intact
bracts
(Table
III).
In
contrast,
debladed
petioles
whose
cut
ends
were
treated
with
a
lanolin
paste
contain-
ing
IAA
responded
to
vertical
orientation
in
just
the
same
way
as
those
of
intact
bracts.
C2H4
production
by
IAA-treated
petioles
post-restraint
was
many
times
that
of
the
controls.
When
IAA
in
lanolin
was
applied
to
the
adaxial
surface
of
the
petiole,
the
epinastic
angle
was
greater
than
1000
(text
only).
Spraying
plants
with
4
mm
STS
before
changing
bract
orienta-
tion
had
no
significant
effect
on
the
epinasty
caused
by
the
reorientation
(Table
III).
STS
pretreatment
greatly
increased
post-
Table
III.
Effects
of
Removal
of
the
Blades,
Their
Replacement
with
IAA
and
Spraying
with
Silver
Thiosulfate
on
Post-restraint
Epinastic
Curvature
and
C2H4
Production
of
Reoriented
Poinsettia
Petioles
Means
of
four
branches,
six
petioles
per
branch.
Means
in
each
column
with
no
letter
in
common
are
significantly
different
(P
=
0.05,
Duncan's
Multiple
Range
Test).
C2H4
production
data
were
analyzed
using
a
logarithmic
transformation.
Treatment
Orientation
Epinastic
C2H4
Produc-
Angle
tion
degrees
nl/g
*
h
Control
Horizontal
3c
0.62g
Vertical
39a
1.67f
Blades
removed
Horizontal
8bc
0.25g
Vertical
16b
1.03fg
Blades
removed
+
Horizontal
16b
7.30cd
IAA
Vertical
41a
7.73cd
Silver
thiosulfate
Horizontal
3c
3.24ef
Vertical
32a
27.36a
Blades
removed
+
sil-
Horizontal
4c
2.16f
ver
thiosulfate
Vertical
18b
5.25de
Blades
removed
+
sil-
Horizontal
13bc
16.39b
ver
thiosulfate
+
Vertical
34a
21.04b
IAA
restraint
C2H4
production
by
all
petioles,
regardless
of
other
treatments.
When
poinsettia
plants
were
exposed
to
15
,il/l
C2H4
for
24
h,
the
strong
epinastic
response
of
control
plants
(epinastic
angle
610)
was
completely
absent
in
plants
which
had
been
sprayed
18
h
before
the
start
of
the
C2H4
treatment
with
4
mM
STS
(text
only).
DISCUSSION
A
marked
epinastic
response
of
petioles
to
changed
orientation
was
attributed
by
Lyon
(10)
to
a
redistribution
of
auxin
in
the
petiole
resulting
from
the
reorientation.
This
simple
hypothesis
was
challenged
by
Leather
et
al.
(8)
who
showed
that
plants
rotated
on
a
clinostat
produced
significant
quantities
of
C2H4,
and
that
epinastic
responses
to
changed
orientation
could
be
inhibited
by
10%1o
CO2.
They
contended
that
position-induced
epinasty
was
analogous
to
other
epinastic
responses
and
was
caused
by
a
change
in
auxin
distribution
induced
by
increased
endogenous
C2H4
concentrations.
Recent
reports
have
concluded
that
the
increased
C2H4
produc-
tion
observed
in
reoriented
poinsettia
petioles
is
caused
by
the
stress
of
reorientation
(13-15).
It
appears
that
simple
mechanical
stress
cannot
be
the
cause
of
increased
C2H4
production
in
poin-
settia
petioles
restrained
upwards
for
5
days.
It
has
already
been
noted
that
merely
rotating
plants
on
a
clinostat
results
in
increased
C2H4
production
(10).
Downward
bending
of
the
petioles
(which
imposes,
if
anything,
more
mechanical
stress
than
upward
bend-
ing)
did
not
increase
C2H4
production
rates
over
those
of
control
petioles
(Table
I).
Whatever
the
cause of
the
enhanced
ethylene
production
in
reoriented
poinsettia
petioles,
the
data
reported
here
do
not
sup-
port
the
contention
that
C2H4
is
responsible
for
epinastic
curva-
ture.
Treatment
of
poinsettias
prior
to
reorientation
with
AOA,
a
specific
inhibitor
Of
C2H4
synthesis
(20),
reduced
the
rate
Of
C2H4
production
to
that
of
the
control
petioles
(Table
II),
but
the
post-
restraint
epinastic
angle
of
the
reoriented
petioles
was
unchanged.
Similarly,
while
treatment
with
STS,
a
specific
inhibitor
of
C2H4
action
(18),
completely
prevented
the
epinastic
response
of
poin-
settia
petioles
to
exogenous
C2H4,
it
had
no
effect
on
the
devel-
opment
of
epinasty
in
reoriented
petioles
(Table
III).
The
stimu-
lation
of
post-restraint
C2H4
production
by
STS
is
similar
to
the
effect
of
Ag+
in
other
vegetative
tissues
(1).
Plant
Physiol.
Vol.
67,
1981
951
OFF
i
l
Plant
Physiol.
Vol.
67,
1981
It
appears
likely
that
the
epinastic
responses
observed
here
result
from
changed
distribution
of
auxin
in
the
petioles
(10,
11).
In
plants
exposed
to
exogenous
C2H4
(2)
or
subject
to
waterlogging
(4,
5),
this
redistribution
is
induced
by
C2H4
(11).
Redistribution
of
auxin
appears
also
to
be
important
in
the
epinastic
response
of
reoriented
petioles.
When
blades
were
removed
from
poinsettia
bracts,
reorientation
of
the
petioles
caused
no
epinasty,
although
post-restraint
C2H4
production
was
enhanced
by
the
reorientation
(Table
III).
Placing
1%
IAA
in
lanolin
paste
on
the
cut
stump
restored
the
response
of
the
petioles
to
reorientation.
Since
the
bracts
are
known
to
be
a
source
of
auxin
in
poinsettias
(6),
it
is
reasonable
to
assume
that
the
epinastic
response
results
from
a
changed
distribution
of
auxin
in
the
petiole.
Certainly
a
very
striking
epinasty
was
induced
by
applying
IAA
to
the
adaxial
surface
of
the
petioles.
Inasmuch
as
our
data
fail
to
support
the
hypothesis
that
C2H4
is
the
cause
of
the
redistribution
of
auxin
in
reoriented
poinsettia
petioles,
we
suggest
that
in
such
petioles
the
redistribution
of
auxin
is
the
result
of
the
change
in
orientation
itself.
This
view
is
supported
by
the
observation
that
downward
reorientation
of
poinsettia
bracts
caused
only
a
slight
epinastic
response
(Table
I);
auxin
transport
is
well
known
to
be
inhibited
in
inverted
organs
(9).
We
would
suggest
that
the
stimulation
of
C2H4
production
in
reoriented
poinsettia
petioles
(13-15,
17)
is
most
likely
to
be
a
response
to
changed
auxin
distribution
in
the
petiole
(19).
LITERATURE
CITED
1.
AHARONI
N,
JD
ANDERSON,
M
LIEBERMAN
1979
Production
and
action
of
ethylene
in
senescing
leaf
discs.
Plant
Physiol
64:
805-809
2.
BEYER
EM
JR
1976
Silver
ion:
a
potent
anti-ethylene
agent
in
cucumber
and
tomato.
Hortscience
11:
195-196
3.
BEYER
EM
JR
1976
A
potent
inhibitor
of
ethylene
action
in
plants.
Plant
Physiol
58:
268-271
4.
BRADFORD
KJ,
DR
DILLEY
1978
Effects
of
root
anaerobiosis
on
ethylene
production,
epinasty
and
growth
of
tomato
plants.
Plant
Physiol
61:
506-509
5.
BRADFORD
KJ,
SF
YANG
1980
Xylem
transport
of
l-aminocyclopropane-l-
carboxylic
acid,
an
ethylene
precursor,
in
waterlogged
tomato
plants.
Plant
Physiol
65:
322-326
6.
GILBERT
DA,
KC
SINK
1971
Regulation
of
endogenous
indoleacetic
acid
and
keeping
quality
of
poinsettia.
J
Am
Soc
Hortic
Sci
96:
3-7
7.
LARSON
RA,
JW
LoVE,
DL
STRIDER,
RK
JONES,
JR
BAKER,
KF
HORN
1978
Commercial
poinsettia
production.
NC
Agric
Ext
Serv
Bull
AG-108
8.
LEATHER
GR,
LE
FORRENCE,
FB
ABELES
1972
Increased
ethylene
production
during
clinostat
experiments
may
cause
leaf
epinasty.
Plant
Physiol
49:
183-
186
9.
LIrrrE
CHA,
MHM
GOLDSMITH
1967
Effect
of
inversion
on
growth
and
move-
ment
of
indole-3-acetic
acid
in
coleoptiles
Plant
Physiol
42:
1239-1245
10.
LYON
CJ
1963
Auxin
transport
in
leaf
epinasty.
Plant
Physiol
38:
567-574
11.
LYON
CJ
1970
Ethylene
inhibition
of
auxin
transport
by
gravity
in
leaves.
Plant
Physiol
45:
644-646
12.
REID
MS,
JL
PAUL,
MB
FARHOOMAND,
AM
KOFRANEK,
GL
STABY
1980
Pulse
treatments
with
the
silver
thiosulfate
complex
extend
the
vase
life
of
cut
carnations.
J
Am
Soc
Hort
Sci
105:
25-27
13.
SACALIS
JN
1977
Epinasty
and
ethylene
evolution
in
petioles
of
sleeved
poinsettia
plants.
Hortscience
12:
388
14.
SACALIS
JN
1978
Ethylene
evolution
by
petioles
of
sleeved
poinsettia
plants.
Hortscience
13:
594-596
15.
SALTVEIT
ME
JR,
DM
PHARR,
RA
LARSON
1979
Mechanical
stress
induced
ethylene
production
and
epinasty
in
poinsettia
cultivars.
J
Am
Soc
Hortic
Sci
103:
712-715
16.
STABY
GL,
JF
THOMPSON,
AM
KOFRANEK
1978
Postharvest
characteristics
of
poinsettias
as
influenced
by
handling
and
storage
procedures.
J
Am
Soc
Hortic
Sci
103:
712-715
17.
STABY
GL,
BA
EISENBERG,
JW
KELLY,
MP
BRIDGEN,
MS
CUNNINGHAM
1979
Petiole
ethylene
levels
and
epinastic
petioles
of
'Annette
Hegg
Dark
Red'
and
'Improved
Rochford'
poinsettias
as
affected
by
sleeving
and
storage
treatments.
Hortscience
14:
445
(Abstract)
18.
VEEN
H,
SC
VAN
DE
GEUN
1978
Mobility
and
ionic
form
of
silver
as
related
to
longevity
of
cut
carnations.
Planta
140:
93-96
19.
YANG
SF
1980
Regulation
of
ethylene
biosynthesis.
Hortscience
15:
238-243
20.
Yu
Y,
DO
ADAMS,
SF
YANG
1979
I-Aminocyclopropanecarboxylate
synthase,
a
key
enzyme
in
ethylene
biosynthesis.
Arch
Biochem
Biophys
198:
280-286
952
REID
ET
AL.
... Two theories of the mechanism of epinasty have been proposed. In one, ethylene affects auxin transport, causing the concentration on the adaxial side of petioles to become higher than that on the abaxial side, thus promoting unequal growth (Reid et al., 1981). In the other, ethylene directly promotes elongation on the adaxial side (Palmer, 1976;Ursin and Bradford, 1989). ...
... In the other, ethylene directly promotes elongation on the adaxial side (Palmer, 1976;Ursin and Bradford, 1989). Both theories describe growth of cells on the adaxial side Palmer, 1976;Reid et al., 1981;Ursin and Bradford, 1989). Because most studies of epinasty used true leaves of tomato, the physiology of epinasty in other species and organs is unknown, notably in cotyledons of Japanese radish. ...
... Ethylene promotes leaf curling through epinasty, which is due to the expansion of cells on the adaxial side of the leaf (Crocker et al., 1932;Crocker, 1948;Kang, 1979;Palmer, 1985). Most previous studies of epinasty tested true leaves and petioles, and there are few studies of other organs (Reid et al., 1981). Hence in cotyledons of Japanese radish, to identify the affecting process of ethylene in cellular level in cotyledon curling, the cell number and length in cotyledons with and without ethylene treatment should be considered (Fig. 8). ...
Article
During the transport of vegetables, it is important to maintain quality. The cotyledons of Japanese radish ( Raphanus sativus var. longipinnatus ) sprouts curl during transport, lowering quality. It is known that ethylene causes the leaf curling of some true leaves by promoting cell growth on the adaxial side (epinasty); however, the mechanism of cotyledon curling is unknown. We investigated the effect of ethylene on cotyledon curling of Japanese radish sprouts. Curling was promoted by exogenous treatment with ethylene and repressed by treatment with 1-methylcyclopropene, an inhibitor of ethylene perception. Microscopic observation of ethylene-exposed curled cotyledons and normal cotyledons indicates that ethylene did not affect cell number but did inhibit transverse (lateral) cell growth on the abaxial side of the cotyledons, causing cotyledon curling through differential growth. Ethylene inhibition of cell growth on the abaxial side of leaves has not been reported before. We show a new mechanism responsible for curling.
... LK11 strain showed a significant increment in several growth attributes [58]. Ethylene is a plant hormone known to regulate several processes such as the ripening of fruits, the opening of flowers or the abscission of leaves [59]. However, it also promotes seed germination, secondary root formation and root-hair elongation [60]. ...
Article
Full-text available
Many rhizospheric bacterial strains possess plant growth-promoting mechanisms. These bacteria can be applied as biofertilizers in agriculture and forestry, enhancing crop yields. Bacterial biofertilizers can improve plant growth through several different mechanisms: (i) the synthesis of plant nutrients or phytohormones, which can be absorbed by plants, (ii) the mobilization of soil compounds, making them available for the plant to be used as nutrients, (iii) the protection of plants under stressful conditions, thereby counteracting the negative impacts of stress, or (iv) defense against plant pathogens, reducing plant diseases or death. Several plant growth-promoting rhizobacteria (PGPR) have been used worldwide for many years as biofertilizers, contributing to increasing crop yields and soil fertility and hence having the potential to contribute to more sustainable agriculture and forestry. The technologies for the production and application of bacterial inocula are under constant development and improvement and the bacterial-based biofertilizer market is growing steadily. Nevertheless, the production and application of these products is heterogeneous among the different countries in the world. This review summarizes the main bacterial mechanisms for improving crop yields, reviews the existing technologies for the manufacture and application of beneficial bacteria in the field, and recapitulates the status of the microbe-based inoculants in World Markets.
... Flooded plants sprayed with STS had a 40-fold greater rate of C 2 H 4 evolution than did F plants not sprayed with STS (Table 1). Stimulation of C 2 H 4 biosynthesis by STS has been reported for other systems as well (Aharoni et al., 1979;Reid et al., 1981) and was hypothesized to result from attachment of Ag + ions to C 2 H 4 receptor sites, thereby preventing binding of C 2 H 4 essential for feedback repression of additional C 2 H 4 biosynthesis (Aharoni et al., 1979). However, the absence of elevated C 2 H 4 evolution from NF + STS plants indicates that this C 2 H 4action inhibitor did not stimulate l-aminocyclopropane-1-carboxylic acid (ACC)synthesis. ...
Article
Full-text available
The relative contributions of auxin and ethylene (C 2 H 4 ) in stimulating the initiation of adventitious root primordia (ARP) and their subsequent development into adventitious roots (ARs) by flooded tomato (Lycopersicon esculentum Mill. PI 406966) seedlings were evaluated using TIBA and STS. Flooded plants treated with STS (F + STS) produced ≈ 40% as many emerged ARs as plants that were flooded only (F). Only 7% of the ARP initiated by F + STS plants developed enough to emerge through the epidermis by 120 hours of treatment compared with 95% emerged for F plants. A band of TIBA applied below the lowest leaves of flooded plants (F + TIBA) virtually eliminated AR formation. Plants with two or four leaves below the TIBA band produced 16- and 35-fold more ARs, respectively, than those with no leaves below the TIBA band. Relative to nonflooded (NF) plants, F + STS plants exhibited a nearly 40-fold increase in C 2 H 4 evolution, while F and F + TIBA plants exhibited about a 5-fold increase in C 2 H 4 production. These results suggest that auxin accumulation at or above the floodline is essential for ARP initiation and that auxin action is not mediated through C 2 H 4 . Ethylene may be required for elongation of flood-induced ARP leading to their emergence as ARs. Chemical names used: 2,3.5 -triiodobenzoic acid (TIBA): silver thiosulphate (STS).
... Ethylene is a second phytohormone that might be involved in leaf epinasty, for the main reason that it can cause differential growth, in terms of petiole epinasty (Jackson and Campbell, 1976;Reid et al., 1981;El-Iklil et al., 2000) or an exaggerated apical hook (Guzman and Ecker, 1990;Stepanova and Alonso, 2005). Other than affecting the sinksource balance, disbudding might enhance ethylene production, since plants are wounded which may cause an increase in ethylene production (Druege, 2006). ...
Article
Breeding for a certain trait is only possible when the phenotypic variation that is caused by genotypic variation can be estimated. For traits that strongly depend on environmental conditions, this can be extremely difficult and knowledge and collaboration with experts from other disciplines becomes essential. A wellknown example is breeding for disease resistance. Here, we describe a similar approach to assist breeding against adverse leaf deformations that severely reduce the ornamental value of some chrysanthemum (Dendranthema × grandiflora) genotypes during greenhouse cultivation in winter. These leaf deformations occur rather unpredictably, but seem to be related to the increased use of assimilation light. To breed against this trait knowledge is needed (i) about inductive environments in which sensitive and insensitive genotypes are distinguishable, and (ii) about the physiological background associated with leaf epinasty. In this paper hypothetical physiological factors and mechanisms are discussed, which may mediate effects of light spectrum and greenhouse climate on leaf epinasty. One factor involved could be starch accumulation, since leaf epinasty usually aggravates after disbudding - a practice that most probably alters the sink-source balance. Additionally, light spectra can affect the circadian clock and thereby disturb starch synthesis and breakdown resulting in accumulation. Both within and independent of this process, plant hormones such as auxin and ethylene may play a role in leaf epinasty. This theoretical framework will be used to further investigate the physiological background of leaf epinasty and to come up with a test in which susceptibility for leaf epinasty can be assessed.
Book
Behandeling van fysiologische, technische en organisatorische factoren die van invloed zijn op de kwaliteit van snijbloemen
Article
Mature ‘Valencia’ fruit were treated with 5-chloro-3-methyl-4-nitro-1H-pyrazole (CMNP), and the ethylene inhibitors aminoethoxy vinyl glycine (AVG) and silver thiosulfate (STS), to assess involvement of ethylene in abscission via CMNP. Fruit detachment force (FDF) and ethylene evolution were measured over time. Accumulation of the ethylene precursor 1-aminocyclopropane-1-carboxylate (ACC) in peel upon CMNP application was assessed and impact of application of ACC on FDF was estimated when applied 1 cm away from the abscission zone (AZ), to determine its potential as a signaling molecule in promoting fruit loosening. CMNP when applied alone reduced FDF by 50%. AVG and STS inhibited fruit loosening considerably at 500 µM and 10 mM, respectively, when applied with 2 mM CMNP. ACC accumulation in peel was highest 2 days after CMNP application, which preceded the maximum decline in FDF which occurred a day later, indicating that ACC serves as a potential signaling molecule that triggers abscission in the AZ. The results of the study support the hypothesis that abscission via CMNP application is at least partly ethylene dependent. However, the decline in FDF by ACC was less than 50% of control which suggested involvement of another pathway in abscission via CMNP in sweet orange.
Chapter
General recognition of ethylene, a simple hydrocarbon gas (C2H4), as a plant hormone has come about only relatively recently, although it has been known for more than three-fourths of a century that the gas has numerous interesting effects on growth and development. D. N. Neljubow, a Russian physiologist, evidently was the first scientist to write about ethylene action on plants. In 1901 he recorded that ethylene, which he identified as a component of illuminating gas, causes the classical “triple response” of etiolated pea seedlings. This response includes inhibition of stem elongation, increase in radial expansion (swelling) of stems, and a horizontal orientation of stems to gravity (see Fig. 6.13). Some years later (1910) H. H. Cousins advised the Jamaican government that oranges and bananas should not be stored together on ships because some unidentified volatile agent would cause the bananas to ripen prematurely.
Chapter
Long before it was established that plant metabolism and growth is regulated and influenced by plant hormones, the action of the plant hormone ethylene on plants was observed and ethylene was recognized as the inducing agent. The first reports on ethylene action date back to 1858, describing plant responses to illuminating gas. At the end of the 19th century a pineapple farmer on the Azores, experimenting with fumes in the greenhouse to kill insects, discovered an earlier flowering of the pineapple plants after this treatment. In the following years the method to induce flowering of pineapple in the greenhouse by fumes became common on the Azores. This was probably the first application of a “plant growth regulator” in agriculture. In a report of 1901, the “triple response” of etiolated pea seedlings (growth inhibition, thickening of the subapical region, horizontal nutation) was observed to occur in the presence of illuminating gas and ethylene was identified as the inducing agent. In 1912 the induction of fruit ripening by ethylene was recognized. The role of ethylene in flower induction of pineapple was established in 1932 (Rodriguez, 1932).
Article
Transport stress of miniature roses can affect their postharvest longevity. Transport stress includes dark storage, fluctuating temperature, exposure to ethylene, high humidity, and mechanical damage. The postharvest quality of three cultivars of Parade® miniature potted roses (Rosa x hybrida) from three growers in Denmark was evaluated during winter and summer 1994, using 0, 2, or 4 days Simulated Transport (ST). The main causes of reduced postharvest longevity were wilted flowers, infection by Botrytis and an increased number of yellow buds. After 18 days in a Simulated Postharvest Environment (SPE) there were no differences in the percentage wilted flowers for all plants ST for 0 or 2 days. The percentage of wilted flowers increased for 2 of the 3 cultivars exposed to 4 days ST as compared to controls. The degree of wilting was also dependent on the origin of the plants and was less severe in summer than in winter. The number of yellow buds and infection by Botrytis was higher in plants exposed to 4 days ST, and was more pronounced in winter. We conclude that if the initial quality of the miniature potted rose is high and stress conditions during transport are controlled, postharvest longevity can be maximized.
Article
Full-text available
RESUMEN Se utilizaron plantas de nochebuena cv. Freedom roja en madurez comercial y fueron tratadas con 1-MCP con las dosis de 0, 250, 500 y 750 nL • L-1 por 24 horas en cámaras de gaseo. Las variables evaluadas fueron: apariencia visual, color en hojas y en brácteas y epinastia en un modelo completamente al azar con 9 repeticiones, una planta fue la unidad experimental. Se realizó ANOVA y comparación de medias de Tukey (P≤ 0.05). El uso de 750 nL • L-1 mantuvo la apariencia visual por más tiempo que el resto de los tratamientos, así como el color en hojas. No tuvo efecto sobre el color de brácteas. El porcentaje de epinastia fue menor en los primeros días con el uso de 750 nL • L-1. El uso de 1-MCP mantiene por mayor tiempo la apariencia visual, el color en hojas y retiene la epinastia en nochebuena. ABSTRACT Poinsettia cv. Freedom Red plants with commercial maturity were used and 0, 250, 500 and 750 nL • L-1 doses of 1-MCP during 24 hour in a gas chamber were applied. The evaluated variables were: visual appearance, color in leaves and bracts, epinasty; with a completely random design with 9 repetitions, one plant was the experimental unit. ANOVA was carried out with a Tukey´s average comparison (P≤ 0.05). 750 nL • L-1 mantained the visual appearance for a longer time than the rest of the treatments, as the color of the leaves. 1-MCP did not have an effect over the color of the bracts. The percentage of epinasty was less in the first days with the use of 750 nL • L-1. 1-MCP keeps the visual appearance, the color of the leaves and retains the epinasty in poinsettia for a longer period of time.
Article
Full-text available
The effect of a 180° displacement from the normal vertical orientation on longitudinal growth and on the acropetal and basipetal movement of ¹⁴C-IAA was investigated in Avena sativa L. and Zea mays L. coleoptile sections. Inversion inhibits growth in intact sections (apex not removed) and in decapitated sections supplied apically with donor blocks containing auxin. Under aerobic conditions, inversion inhibits basipetal auxin movement and promotes acropetal auxin movement, whereas under anaerobic conditions, it does not influence the movement of auxin in either direction. Inversion retards the basipetal movement of the peak of a 30-minute pulse of auxin in corn. The inversion-induced inhibition of basipetal auxin movement is not explained by an effect of gravity on production, uptake, destruction, exit from sections, retention in tissue, or purely physical movement of auxin. It is concluded that inversion (a) inhibits basipetal transport, the component of auxin movement that is metabolically dependent, and as a result (b) inhibits growth and (c) promotes acropetal auxin movement.
Article
The mobility of different ionic forms of silver ((110m)Ag) has been studied using semiconductor radiation detectors. Silver, applied as silvernitrate (2mM), moves upward in the stems of cut carnations (Dianthus caryophyllus L.) at about 3 cm day(-1). This transport has the characteristics of a chromatographic exchange transport, but is not promoted by the addition of other cations (K(+) or Ca(2+)). The silverthiosulphate anionic complex is transported at the same speed as [(32)P]phosphate (about 2 m h(-1)); orders of magnitude faster than Ag(+). The antiethylene action of silver is preserved in this complex, as shown by a significant improvement of the longevity of carnation flowers in the presence or absence of ethephon, even after a short treatment with the silverthiosulphate complex. Analysis of the silver content of different flower parts after a silverthiosulphate treatment shows a distinct accumulation in the receptacle, possibly associated with the antiethylene action.
Article
Ethylene production fromtomato(Lycopersicum esculentum L.cv.Rutgers) plants basedon a clinostat doubledduring thefirst 2hoursofrotation. Carbondioxide blocked theap- pearance ofleafepinasty normally associated withplants rotated on a elinostat. Theseresults supporttheideathat epinasty ofclinostated plants wasduetoincreased ethylene production andnottothecancellation ofthegravitational pull onauxintransport inthepetiole.
Article
The biosynthesis of the gaseous phytohormone ethylene is a highly regulated process. A major point of regulation occurs at the generally rate-limiting step in biosynthesis, catalyzed by the enzyme ACC synthase (ACS). ACS is encoded by a multigene family, and different members show distinct patterns of expression during growth and development, and in response to various external cues. In addition to this transcriptional control, the stability of the ACS protein is also highly regulated. Here we review these two distinct regulatory inputs that control the spatial and temporal patterns of ethylene biosynthesis.
Article
1-Aminocyclopropanecarboxylate (ACC) synthase, which catalyzes the conversion of S-adenosylmethionine (SAM) to ACC and methylthioadenosine, was demonstrated in tomato extract. Methylthioadenosine was then rapidly hydrolyzed to methylthioribose by a nucleosidase present in the extract. ACC synthase had an optimum pH of 8.5, and a Km of 20 μm with respect to SAM. S-Adenosylethionine also served as a substrate for ACC synthase, but at a lower efficiency than that of SAM. Since S-adenosylethionine had a higher affinity for the enzyme than SAM, it inhibited the reaction of SAM when both were present. S-Adenosylhomocysteine was, however, an inactive substrate. The enzyme was activated by pyridoxal phosphate at a concentration of 0.1 μm or higher, and competitively inhibited by aminoethoxyvinylglycine and aminooxyacetic acid, which are known to inhibit pyridoxal phosphate-mediated enzymic reactions. These results support the view that ACC synthase is a pyridoxal enzyme. The biochemical role of pyridoxal phosphate is catalyzing the formation of ACC by α,γ-elimination of SAM is discussed.