Plant Molecular Biology 34: 345–352, 1997.
1997 Kluwer Academic Publishers. Printed in Belgium.
Characterisation of a pea hsp70 gene which is both developmentally and
Om Parkash Dhankher, Janice E. Drew
and John A. Gatehouse
Department of Biological Sciences, University of Durham, South Road, Durham DH1 3LE, UK (
Present address: Rowett Research Institute, Bucksburn Road, Aberdeen, UK
Received 31 July 1996; accepted in revised form 24 February 1997
Key words: heat shock, pea (Pisum sativum L.), gene expression, pod ligniﬁcation
A pea pod cDNA library was screened for sequences speciﬁc to lignifying tissue. A cDNA clone (pLP19) encoding
the C-terminal region of a hsp70 heat shock protein hybridised only to pod mRNA from pea lines where pod
ligniﬁcation occurred. Expression of pLP19 was induced by heat shock in leaves, stems and roots of pea and
chickpea plants. Four different poly(A) addition sites were observed in cDNAs derived from the same gene as
pLP19. This gene was fully sequenced; unlike most hsp70 genes, it contains no introns. The 5
contains heat shock elements and other potential regulatory sequences.
Abbreviations: HSE heat shock element; HSP, heat shock protein.
Like all organisms, plants respond to a rapid elev-
ation in environmental temperature by transcriptional
activation of a set of genes that encode protective pro-
teins called heat shock proteins (HSPs). The HSPs
exhibit highly ubiquitous and conserved features, and
are proposed to be essential for cell survival .
The major classes of HSP are distinguished by their
molecular weights: hsp110, hsp90, hsp70, hsp60 and
low-molecular-weight (LMW) hsp (reviewed in ).
Although HSP are produced in response to high tem-
perature, certain speciﬁc HSPs are also found at a sig-
niﬁcant level in normal unstressed cells (constitutive
expression), or are produced at a particular stage of
the cell cycle or during development in the absence of
stress [7, 17, 18, 20]. It has been suggested  that
HSPs (and the related heat shock cognate or HSC pro-
teins) are involved in the folding, assembly and disas-
sembly of proteins and protein containing complexes,
both during normal growth and after heat shock [4, 14,
The composite nucleotide sequence reported for the
HSP70(LP19) gene and the cDNAs derived from it has been submit-
ted to the EMBL Nucleotide Sequence Database under the accession
30]. Many of the agents and treatments that enhance the
activity of the HSP genes are known to cause unfolding
of pre-existing proteins or to induce the synthesis of
unfolded polypeptides[10, 29]. Thus the accumulation
of unfolded peptides could be the signal for increased
expression of HSP genes.
The hsp class designated hsp70 is found in
both eukaryotes and prokaryotes, and represents a
highly conserved multigene family, whose genes are
expressed under a variety of physiological conditions.
The diversity of hsp70 genes is partly accounted for
by the presence of distinct hsp70 homologues in cyto-
plasm , in the lumen of ER  and the mat-
rix of chloroplasts and mitochondria [2, 6, 19]. The
hsp70s are highly homologous and show a high level
of sequence conservation, with at least 50% identity
at the amino acid level . Several plant cytoplasmic
hsp70s have been characterised: in Arabidopsis ,
petunia , maize , soybean  and tomato
. The genes for the hsp70s of plants are activated
by a variety of stresses in addition to heat shock .
For example, wounding, water deﬁcit, abscisic acid,
heavy metals and cold can induce the synthesis of the
GR: 201001914, Pips nr. 135735 BIO2KAP
plan3629.tex; 7/05/1997; 14:12; v.7; p.1