Plant Molecular Biology 35: 683–688, 1997.
1997 Kluwer Academic Publishers. Printed in Belgium.
Sequential expression of two 1-aminocyclopropane-1-carboxylate synthase
genes in response to biotic and abiotic stresses in potato (Solanum tuberosum
Carl D. Schlagnhaufer
, Richard N. Arteca
and Eva J. Pell
Department of Horticulture (
author for correspondence);
Department of Plant Pathology and Environmental
Resources Research Institute, The Pennsylvania State University, University Park, PA 16802, USA
Received 22 November 1996; accepted in revised form 28 May 1997
Key words: ACC synthase, ethylene, potato, ozone, copper, Alternaria solani
Plants produce ethylene in response to many biotic and abiotic stresses. In response to ozone the foliage of potato
genes also occurred in response to Cu
and infection with Alternaria solani. ST-ACS5 expression increases very
rapidly reaching a maximum earlier than ST-ACS4 transcripts, after which ST-ACS5 expression declines. ST-ACS4
expression increases at a slower rate and reaches its maximum after ST-ACS5. The sequential nature of expression
argues that the two genes have different signal transduction and gene regulatory mechanisms.
Ethylene is involved in the regulation of many plant
developmental processes from seed germination to
senescence, and is produced in response to many
environmental stimuli including stress. Tingey et al.
 demonstrated that ozone (O
) exposure resulted
in the production of ethylene by more than 20 differ-
ent plant species, and ethylene emission was highly
correlated with the expression of visible injury. Thus,
it has been proposed that stress ethylene could be a
determining factor in plant sensitivity to O
16, 25]. Plant produce ethylene enzymatically from 1-
methionine via S-adenosyl methionine (AdoMet) and
1-aminocyclopropane-1-carboxylic acid (ACC) .
Since AdoMet is involved in many metabolic path-
ways, the conversion of AdoMet to ACC via the
enzyme ACC synthase is the key regulatory step in
Previously, we  identiﬁed and characterized
a cDNA (originally designated OIP-1; the clone has
been redesignated ST-ACS4 in accordance with stand-
ard nomenclature) for ACC synthase from RNA isol-
-treatedpotato leaves, andshowed that O
Thenucleotidesequencedatareportedwill appear in theEMBL,
GenBank and DDBJ Nucleotide Sequence Databases under the
accession numbers L20634 (ST-ACS4) and U70842 (ST-ACS5).
exposure induced its expression. Increases in mRNA
for ACC synthase reﬂected increased gene transcrip-
tion based on results of nuclear run-on assays .
Potato plants receiving chronic low dose O
also produce elevated levels of ethylene , and ethyl-
ene production was correlated with an increase in the
level of the O
-induced ACC mRNA.
In many developmental and inducible systems,
ACC synthase activity increases as a result of elevated
levels of the mRNA for ACC synthase . A mul-
tigene family for ACC synthase genomic sequences
exists in a number of plant species [4, 9, 13, 21, 27,
28, 30], and the differential expression of ACC syn-
thase genes occurs in response to pathogen infection
, auxin [15, 28, 29], wounding[9, 16, 17, 29], and
plant development [18, 21, 27, 28]. Thus, plants may
regulate ethylene production by differentially express-
ing ACC synthase genes during development or in
response to external stimuli.
If plants manage the complex problem of produ-
cing ethylene when it is needed through differential
duction pathway, and speciﬁc member(s) of the ACC
synthase gene family should be expressed. To test this