Plant Molecular Biology 34: 643–650, 1997.
1997 Kluwer Academic Publishers. Printed in Belgium.
cDNA structure and expression patterns of a low-temperature-speciﬁc wheat
Joyce Ache Gana
, Fedora Sutton
and Donald G. Keneﬁck
Plant Science Department, Box 2108 (
author for correspondence) and
South Dakota State University, Brookings, SD 57007, USA
Received 18 June 1996; accepted in revised form 7 April 1997
Key words: callus, crown tissue, gene expression, low temperature, wheat
The low-temperature (2
C)-speciﬁc wheat cDNA, pTACR7, represents a gene designated tacr7 from hard red
winter wheat (HRWW; Triticum aestivum L. cv. Winoka). The term low-temperature-speciﬁc(LTS) is used because
tacr7 is not induced by ABA or stresses such as salt, dehydration, and heat. pTACR7 was isolated by RT-PCR with
mRNA from wheat crown tissue, the oligonucleotide primers derived from the barley cognate pHVCR8 (GenBank
accession number L28091). Based on the deduced amino acid sequence, TACR7 is highly hydrophobic, with
a single transmembrane domain and an amino acid bias for leucine (19%). Thus, the encoded protein TACR7
is unique among low-temperature-regulated wheat proteins described in the literature. Analysis of steady-state
levels of tacr7 transcripts (630 nt) showed accumulation in wheat seedlings, crown tissue, and callus cultures after
transfer from control (25
C) to low temperature (2
C). No detectable transcripts were observed by northern blot
hybridization with pTACR7 probe from seedling or callus treated with ABA, salt, dehydration, or heat stress. tacr7
transcripts accumulated during 2
C exposure to a greater amount in a freeze-resistant HRWW (FR; SD
than in a freeze-susceptible HRWW (FS; SD
16169) crown tissue, with the largest differencebetween genotypes
3% at 3 weeks.
Freezing resistance in winter wheat can be induced
by exposing plants to a period of low non-freezing
temperature (e.g. 2 to 5
C) for 4 to 6 weeks [2, 14].
Dantumaand Andrews reported that winter wheat
this low temperature treatment.
During low temperature exposure, frequently
referred to in the literature as cold acclimation, a num-
ber of physical and biochemical processes have been
reported [28, 38, 42]. Weiser  ﬁrst proposed that
cold acclimation may involve changes in gene expres-
sion. Guy  and Thomashow  reviewed several
studies demonstrating that changes in gene expression
occur during cold acclimation.
The nucleotide sequence data reported will appear in GenBank
Database under the accession number L28093 (tacr7).
A numberofwheatgenesthat arelow-temperature-
regulated (LTR) are described in the literature.
In reviewing plant acclimation to low-temperature,
Hughes and Dunn  list the LTR wheat genes. They
areWcs120with family membersWcs200 and Wcs66;
Wcs19; and cor39 and Wcor410. These genes encode
of 20–200 kDa. The cDNA for Wcs120 was isolated
by Houde et al.  with the encoded protein shown
to be boiling stable and highly hydrophilic. Amino
acid sequence analysis of Wcs120 reveals consensus
repeated domains found in barley dehydrins and rice
abscisic acid-induced proteins [11, 15, 32]. Anoth-
er high molecular weight protein speciﬁcally induced
by cold acclimation in wheat was described by Ouel-
let et al. . This protein shares similar features to
the 50 kDa protein described by Houde et al.  in
that it is boiling stable and possesses similar repeated
motifs. A cDNA clone corresponding to this 200 kDa
GR: 201001963, Pips nr. 139286 BIO2KAP
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