Plant Science 158 2000 139 – 145
Expression of genes responsible for ethylene production and wilting are differently regulated in carnation Dianthus caryophyllus
L. petals
Yusuke Kosugi
a
, Kenichi Shibuya
a
, Nanako Tsuruno
a
, Yujiro Iwazaki
a
, Atsushi Mochizuki
b
, Toshihito Yoshioka
a
, Teruyoshi Hashiba
a
, Shigeru Satoh
a,
a
Laboratory of Bio-adaptation, Graduate School of Agricultural Science, Tohoku Uni6ersity, Tsutsumidori-amamiyamachi
1
-
1
, Aoba-ku, Sendai
981
-
8555
, Japan
b
Tohoku National Agricultural Experiment Station, Omagari, Akita
014
-
0102
, Japan Received 7 February 2000; received in revised form 3 June 2000; accepted 7 June 2000
Abstract
Carnation petals exhibit autocatalytic ethylene production and wilting during senescence. The autocatalytic ethylene production is caused by the expression of 1-aminocyclopropane-1-carboxylate ACC synthase and ACC oxidase genes, whereas the wilting
of petals is related to the expression of the cysteine proteinase CPase gene. So far, it has been believed that the ethylene production and wilting are regulated in concert in senescing carnation petals, since the two events occurred closely in parallel with
time. In the present study, we investigated the expression of these genes in petals of a transgenic carnation harboring a sense ACC oxidase transgene and in petals of carnation flowers treated with 1,1-dimethyl-4-phenylsulfonylsemicarbazide DPSS. In petals
of the transgenic carnation flowers, treatment with exogenous ethylene caused accumulation of the transcript for CPase and in-rolling wilting, whereas it caused no or little accumulation of the transcripts for ACC oxidase and ACC synthase and
negligible ethylene production. In petals of the flowers treated with DPSS, the transcripts for ACC synthase and ACC oxidase were accumulated, but no significant change in the level of the transcript for CPase was observed. These results suggest that the
expression of ACC synthase and ACC oxidase genes, which leads to ethylene production, is differentially regulated from the expression of CPase, which leads to wilting, in carnation petals. © 2000 Elsevier Science Ireland Ltd. All rights reserved.
Keywords
:
Carnation flower senescence; 1,1-Dimethyl-4-phenylsulfonylsemicarbazide; Ethylene production; Gene expression; Petal wilting; Transgenic carnation
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1. Introduction
Ethylene is the primary plant hormone involved in the senescence of cut carnation flowers [1 – 3]. A
large amount of ethylene is synthesized several days after full opening of the flowers [4 – 6], several
hours after compatible pollination [7 – 9] or soon after the treatment with exogenous ethylene [2,10].
Ethylene is produced first in the pistil during natural and pollination-induced senescence [11,12].
Then the produced ethylene, acting as a diffusible signal, is perceived by petals and induces autocata-
lytic ethylene production in the petals, resulting in in-rolling of petal margins and wilting of the
whole petals. A large portion of ethylene produced by senescing carnation flowers comes from the
petals. On the other hand, exogenous ethylene applied to carnation flowers directly acts on the
petals, and induces autocatalytic ethylene produc- tion and wilting of the petals Shibuya et al.,
submitted.
Abbre6iations
:
ACC, 1-aminocyclopropane-1-carboxylate; AdoMet, S-adenosyl-
L
-methionine; CPase,
cysteine proteinase;
CTAB, cetyltrimethyl-ammonium bromide; CaMV, cauliflower mosaic virus;
DIG, digoxygenin; DPSS, 1,1-dimethyl-4-phenylsulfonylsemicar- bazide; GUS, b-glucuronidase; HPT, hygromycin phosphotrans-
ferase; RT, reverse transcription.. Corresponding author. Tel.: + 81-22-717-8831; fax: + 22-717-
8834. E-mail address
:
ssatohbios.tohoku.ac.jp S. Satoh. 0168-945200 - see front matter © 2000 Elsevier Science Ireland Ltd. All rights reserved.
PII: S 0 1 6 8 - 9 4 5 2 0 0 0 0 3 1 4 - 9
Ethylene is synthesized in plant tissues through the following pathway:
L
-methionine AdoMet ACC ethylene. ACC synthase and ACC oxidase
catalyze the last two reactions [13,14]. The increase in ethylene production in carnation petals is ac-
companied by the expression of genes for both ACC synthase DC-ACS
1
[15] and ACC oxidase DC-ACO
1
corresponding to pSR120 cDNA [16]. Petal wilting in flower senescence is caused by
the decomposition of cell constituents by hy- drolytic enzymes such as protease and nuclease
[17,18]. CPase is probably one of the enzymes responsible for hydrolytic degradation of cell com-
ponents leading to cell death during senescence of petals [17,18]. A CPase gene is up-regulated during
natural, pollination-induced and exogenous ethyl- ene-induced senescence of carnation petals [19]. So
far, it has been believed that autocatalytic ethylene production and petal wilting are regulated in con-
cert and can not be separated, since they occur closely in parallel.
Transgenic plants with suppressed ethylene pro- duction have been used as a powerful tool for
understanding the regulation of the biosynthesis and action of ethylene in plant tissues. For in-
stance, Theologies et al. [20], using a transgenic tomato with suppressed ethylene production, re-
vealed that both ethylene-independent and ethyl- ene-dependent signal transduction pathways were
responsible for ripening of tomato fruit.
In the present work, we generated a transgenic carnation plant harboring a sense ACC oxidase
transgene, and examined the response of their petals to exogenous ethylene with regard to the
induction of in-rolling, ethylene production and expression of genes involved in these events. Fur-
thermore, we examined the changes in the levels of the transcripts for ACC synthase, ACC oxidase
and CPase in petals of non-transformed carnation flowers after treatment with DPSS. We report that
the expression of ACC synthase and ACC oxidase genes, which leads to ethylene production and that
of CPase, which leads to wilting of petals, are differentially regulated in carnation petals.
2. Materials and methods
