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

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R.G. Trischuk, B.S. Schilling, M. Wisniewski and L.V. Gusta
microarrays that represented Arabidopsis seed expressed genes. The authors used the
Arabidopsis array to profile the transcriptone of oilseed rape (Brassica napus) seeds
and found expression patterns correlated well between the two species. Most seed
specific probes identified in Arabidopsis provided seed specific signals in B. napus,
however, the correlation coefficients for B. napus were slightly lower than those from
Arabidopsis. These studies mentioned applied microarray analysis to isolate sets of
genes expressed across tissues and between species. However, the use of microarray
analysis can be expanded to study gene expression profiles of different tissues from
different plant species subjected to abiotic stress.
Plants tolerate many variable environmental conditions during growth and
development. Efforts have been made to understand molecular pathways involved in
plant responses to adverse conditions. Desikan et al. (2001) subjected Arabidopsis to
oxidative stress and found an increase in genes involved in cell rescue and defense as
well as other metabolic functions from the H 2
O 2
treatment. Approximately 34 % were of
unknown gene function, 18 % were involved in transcription, 18 % were involved in cell
response or defense, 12 % were involved with metabolism, 8 % were involved in cellular
organization and biogenesis, 6 % were involved with signal transduction, 3 % were
involved with protein destination and transport and 1 % were involved with energy
production. Kreps et al. (2002) studied expression profiles in the leaves and roots of
Arabidopsis subjected to hyperosmotic, salt, and cold conditions. Kreps et al. (2002)
showed the majority of the transcriptome changes were stimulus specific and distinct
sets of genes were expressed during hyperosmotic, salt, and cold stress. During the
initial phase of the stress response, less than 5 % of transcript changes were shared by
all three stress conditions and the number of genes common between all three stress
conditions decreased the longer plants were exposed to the conditions. Seki et al.
(2001) used full-length cDNAs from Arabidopsis grown in different conditions and
from various developmental stages from germination to mature seed. Seki et al. (2001)
isolated a group of genes involved with drought, some which were not previously
identified as drought responsive. A more detailed analysis with Arabidopsis genomic
sequences indicated that 12 of the genes isolated were regulated by the dehydration
responsive element (DRE) which has been previously reported as essential for the
expression of drought-responsive genes (Yamaguchi-Shinozaki and Shinozaki 1994).
Such an approach may offer new information about cis acting elements and the transcription
factors that bind to them.
Watkinson et al. (2003) measured changes in gene expression of loblolly pine
exposed to both mild and severe drought stress. Water was withheld from rooted
plantlets at -1MPa and -1.5 MPa for mild and severe stress, respectively. Net photosynthesis
was measured for each level of stress and RNA isolated from the needles to
estimate photosynthetic acclimation in response to drought stress. Under mild stress,
loblolly pine showed a reduction in photosynthetic rate followed by recovery to near
control levels in subsequent drought cycles. The microarray analysis consisted of
cDNA clones from 5 pine EST libraries and gene expression profiles were correlated