Plant Science 148 1999 59 – 67
Low temperature-induced modifications of cell wall content and polysaccharide composition in leaves of winter oilseed rape
Brassica napus L. var. oleifera L.
Maria Kubacka-Ze˛balska, Alina Kacperska
Institute of Experimental Plant Biology, Warsaw Uni6ersity, Pawin´skiego
5
A, PL-
02
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106
Warsaw, Poland Received 28 December 1998; received in revised form 4 May 1999; accepted 24 June 1999
Abstract
Pronounced modifications in cell wall content and polysaccharide composition were observed in the young leaves of winter oilseed rape plants Brassica napus L. var. oleifera L. cv Jantar grown for 3 weeks in cold 2°C and then exposed to a brief
freezing and thawing treatment − 5°C for 18 h. In the cold-grown leaf blades, the increased cell wall content was associated with higher levels of non-covalently bound pectins. The content of galactose, arabinose and glucose in pectins and of galactose and
arabinose in hemicelluloses also increased in these leaves. Exposure of cold-acclimated plants to a freeze-thaw treatment resulted in decreased cell wall content, reduced levels of non-covalently bound pectins and decreased contents of xylose and glucose in the
hemicellulose fraction. Our findings indicate that the pattern of modifications of cell wall content and polysaccharide composition depends on the range of temperatures the plant has been exposed to. The role of the cell wall in cold-acclimated and freezing
treated plants is discussed. © 1999 Elsevier Science Ireland Ltd. All rights reserved.
Keywords
:
Brassica napus var. oleifera; Cell wall; Cold; Freezing; Polysaccharides; Winter oilseed rape leaves www.elsevier.comlocateplantsci
1. Introduction
Prolonged growth of chilling-resistant herba- ceous plants at temperatures just above 0°C results
in the modification of their growth pattern [1] and the adjustment of cellular metabolism to low tem-
perature conditions, i.e. in acclimation of plants to the cold [2]. Another attribute of plant acclimation
in cold is increased resistance of cells to extracellu- lar freezing [3]. This property is further increased
by a short exposure of plants to sub-zero tempera- tures [3 – 5].
Aside from other factors, resistance of plant cells to freezing depends on the presence of cell
walls [6,7]. Rajashekar and Burke [8] showed that the movement of water from cells during extracel-
lular freezing and its consequences, cell dehydra- tion and cell collapse, depend on cell wall
mechanical properties. It has been proposed that cell wall rigidity may be an important factor in cell
resistance to freeze-induced dehydration [9].
The composition of cell wall polysaccharides has been shown to be an important component of
plant adaptive responses to factors inducing cell dehydration [10 – 13]. However, information on the
low temperature-induced modifications in cell wall composition is very limited. In the cold-grown
plants or suspension cultures, cell wall thickening [14 – 16], deposition of extracellular callose [17],
accumulation of lipid polymers in cell walls [18] or
Abbre6iations
:
CA, cold-acclimated leaves; CAF
1
, cold-acclimated leaves, subjected to a transient freezing and recovered at 2°C in the
dark for 6 h; CAF
2
, cold-acclimated, prefrozen leaves, subjected to 20-h
recovery at
2°C; CDTA,
trans-1,2-diaminocyclohexane- N,N,N,N-tetraacetic acid; DMSO, dimethyl sulfoxide; EDTA,
ethylenediaminetetraacetic acid; GC, gas chromatography; NA, non- acclimated leaves, sampled at the start of acclimation treatment;
TFA, trifluoroacetic acid. Corresponding author. Tel.: + 48-22-6596072, ext. 57165717;
tel.fax: + 48-22-6584804. E-mail address
:
alkaibbrain.ibb.waw.pl A. Kacperska 0168-945299 - see front matter © 1999 Elsevier Science Ireland Ltd. All rights reserved.
PII: S 0 1 6 8 - 9 4 5 2 9 9 0 0 1 2 2 - 3
a deposition of silica [19], were observed. Such modifications are thought to affect water balance
and the pattern of ice propagation in plant tis- sue rather than the ability of cell walls to un-
dergo deformations.
Our previous experiments performed on cold- grown or on frost pretreated winter oilseed rape
leaves indicated that the activity of cell wall-as- sociated b-galactosidase decreases in cold-accli-
mated winter oilseed rape leaves, whereas it increases rapidly in response to a brief freezing
treatment [20]. The enzyme is responsible for the breakdown of b-galactosyl linkage in pectin and
hemicellulosic polysaccharides [21]. It is involved in the breakage of bonds between cell wall
polysaccharides during cell wall loosening [21,22] and in the degradation of pectic polymers of
galactose during cell growth [23]. The freezing- induced increase in cell capability for the turgor-
dependent
extension growth
was actually
observed in our previous work [5]. Therefore, it may be anticipated that cell wall properties will
differ between cold-acclimated and freeze-af- fected tissues. The major objective of the present
experiments was to verify this supposition by ex- amination of cell wall content and polysaccha-
ride composition in winter rape oilseed rape plants subjected to cold \ 0°C and freezing
B 0°C treatments.
2. Materials and methods
