Plant Molecular Biology 37: 179–185, 1998.
1998 Kluwer Academic Publishers. Printed in Belgium.
Isolation, characterisation and expression of a cDNA for pea
Philippa L. Jones
, David L. Willey
, Peter Gacesa
and John L. Harwood
School of Molecular and Medical Biosciences, University of Wales Cardiff, Museum Avenue, PO Box 911,
Cardiff CF1 3US, UK (
author for correspondence);
Faculty of Science and Engineering, Manchester
Metropolitan University, Manchester M1 5GD, UK
Received 21 May 1997; accepted in revised form 5 December 1997
Key words: cytidylyltransferase, phosphatidylcholine, Pisum sativum
In plants, phosphatidylcholine is the major phospholipid in extra-plastid membranes and is synthesised mainly by
the CDP-choline pathway. Evidence from studies in animals, as well as in plants, suggests that the intermediate
step catalysed by cholinephosphate cytidylyltransferase (CPCT) has a major control in carbon ﬂux to this lipid.
We have isolated a full-length CPCT cDNA (designated PCT2) from Pisum sativum cv. Feltham First using an
Arabidopsis probe and the polymerase chain reaction (PCR). The deduced amino acid of PCT2 is 48%, 43% and
76% identical to the rat, yeast and Brassica napus amino acid sequences, respectively. Expression of the CPCT
protein in Escherichia coli conﬁrmed the activity of the enzyme. Expression of the PCT2 mRNA in pea roots and
stems was increased by treatment with 0.1
M indole-3-acetic acid.
Abbreviations: CPCT, cholinephosphate cytidylyltransferase; IAA, Indole-3-acetic acid
Phosphatidylcholine is the major phospholipid found
in extra-chloroplastic membranes of plant cells and
usually constitutes around half the total phospholipid
content of such membranes . In addition, phos-
phatidylcholineis a substratefor desaturationreactions
. Therefore, this phospholipid has a central role in
responsesto changes in theenvironmentand regulation
of the synthesis of other lipids.
The biosynthesis of phosphatidylcholine occurs
by the CDP-choline pathway or by methylation
of phosphatidylethanolamine, with the CDP-choline
pathway predominating in plants . The nucle-
otide or CDP-choline pathway involves the action of
three enzymes. Choline kinase (EC 184.108.40.206) forms
cholinephosphate and cholinephosphate cytidylyl-
transferase (CPCT; EC 220.127.116.11) catalyses the produc-
tion of CDP-choline. Phosphatidylcholine is synthes-
The nucleotidesequence data reported will appear in theEMBL,
GenBank and DDBJ Nucleotide Sequence Databases under the
accession number Y09101.
ised from CDP-choline by diacylglycerol cholinephos-
photransferase (EC 18.104.22.168.).
There is strongevidence that CPCT is the main reg-
ulatory step of the CDP-choline metabolic pathway in
animals  and there is evidence that this is also true
in plants. Treatment of pea stems with indole-3-acetic
acid (IAA)stimulates stemelongation and signiﬁcantly
increases phosphatidylcholine synthesis . Meas-
urements of enzyme activities indicated that CPCT was
the enzyme in the CDP-choline pathway regulated by
the hormone . Evidence from castor bean endo-
sperm , rye roots  and celery cell cultures 
also suggests that the pathway to phosphatidylcholine
in plants is regulated by CPCT. Because of our previ-
ous work showing hormone effects on CPCT in peas,
we were interested in elucidating more details of this
phenomenon at the molecular level. Therefore, we ini-
tiated studies to isolate and investigate control of the
gene(s) for CPCT in pea.