Agriculture Reference
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However, in order to apply such methods, more knowledge
about the underlying mechanisms regulating the cold tolerance
and acclimatization is required. EST sequencing and cDNA
microarray technologies show that rice is cold responsive with
many of the identifi ed cold regulated genes having a counterpart
in rice. In rice, however, the response is less dynamic than in
the model organism Arabidopsis thaliana and this may explain
its inability to fully acclimatize to cold. Identifi cation of cis-
elements coupled with transcription factors are prominent in
the regulation of the response. Since cold acclimatization is
a quantitative trait, the response of regulation of cold stress
is under combinatorial control of several transcription factor
and it is noted that this should be taken into account when
identifying binding sites.
Many species of temperate origin may develop tolerance
when exposed to temperature change. This process is known
as thermal adaptation that is associated with biochemical and
physiological responses caused mainly by alternations in lipidic
fl uidity of membranes (Hu et al. 2004). Cold acclimatization
involves altered gene expression that affects membrane
composition and accumulation of compatible solutes (Uemura
et al. 2006). This is possible through the action of specifi c
enzymes which are capable of altering the level of lipidic
unsaturation of membranes. Therefore, fatty acid composition
of the lipids that constitute the plant cell membranes. Genotypes
differ for total saturated and unsaturated fatty acids only under
the cold temperature treatment—more abundant fatty acids
are linoleic, linolenic and palmitic which showed that the two
differed between tolerant and sensitive genotypes. Linolenic
acid increased after cold exposure in cold tolerant genotypes
while palmitic acid decreased and an opposite behavior was
found in the cold sensitive genotypes (Cruz et al. 2010).
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