Physiology and Molecular Biology of Stress ... - KHAM PHA MOI

Freezing Stress
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(1997). However, cultivars that did not show increases in freezing tolerance beyond -17
°C under field conditions were generally capable of cold acclimating further under
controlled environment conditions (Gusta et al., 2001).
The results from the microarray analysis revealed the expression patterns of
genes during cold acclimation and identified potential transcription factors. The use of
the winter and spring canola types allowed physiological comparisons at key changes
in temperature and isolation of genes not observed in each type. These results can be
applied to comparative and functional genomics. Comparative genomics allow for
phylogenetic analysis of gene families to identify putative orthologs to genes characterized
in Arabidopsis or other plant species, providing information regarding gene
function. Genomic sequences allow for identification of cis regulatory elements based
on phylogenetic conservation and similarity in gene expression. Functional genomics
can be used to study and understand how B. napus responds and adapts to abiotic
stress. Cellular and physiological aspects of gene function in canola can be made when
canola is grown and acclimated in both controlled environment conditions and field
conditions. The function of gene sequences highly correlated to with cold acclimation
can be studied using transgenic approaches to achieve overexpression or silencing of
specific genes.
4. PROTEOMICS
The induction of cold-induced proteins have long been associated with the development
of freezing tolerance (Levitt, 1980). The term “proteomics” is used to describe the
study of alterations and interactions that occur in all the proteins of a plant (i.e., its
‘proteome’). Current research employs highly sophisticated equipment and procedures;
such as two dimensional polyacrylamide gel electrophoresis (2D PAGE)
(Blackstock and Mann, 2000), differential gel expression (DIGE, Amersham Biosciences)
(Swatton et al., 2004) and multidimensional protein identification technology (MudPIT)
(Yates, 1997) for the separation of proteins based on different chemical characteristics.
Highly sensitive mass spectral technology is used to identify each protein and high
capacity computers are used to search the ever expanding databases to determine
qualitative and quantitative changes in protein accumulation patterns.
The term ‘proteomics’ is a relatively new term to describe the study of proteinexpression
profiles within an organism, but in actuality protein research has been conducted
for the past 100 years. Many studies have been conducted to characterize
enzyme variation, protein content and protein synthesis in plants exposed to low temperature
(LT) (Guy, 1990). As early as 1969, cold research scientists realized that many
biochemical and genetic changes were occurring within plants that were exposed to low
temperature (McGown et al., 1969). To characterize these biochemical changes, freeze
stability and isozymic variation of enzymes were measured in non-acclimated (NA) and
acclimated plants (AC) (McGown et al., 1969). Levels of peroxidase activity was measured
in NA and AC plants of four unrelated woody species, revealing that three of four