Transcript Effects of salt stress on the stem growth of Arabidopsis thaliana.

Effects of salt stress on the stem
growth of Arabidopsis thaliana.
Jacob Phillips
Undergraduate Student
Department of Biology
Tennessee Technological University
Cookeville, Tennessee 38505
Introduction
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Increasing soil salinity is imposing stress on biological
conditions for many organisms.
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Environmental stresses (cold, salt, and drought) reduce average yield for most
major crops by 50% as compared to pathogens only 10-20% (Kreps et al. 2002).
Many research projects currently being carried out
examining salt stress.
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Role of stress on proteins.
Role of stress on growth.
Role of stress on photosynthesis/O2 production.
“MKK2 was specifically activated by cold and salt
stress…plants overexpressing MKK2 showed increased salt
and freezing tolerance.” (Teige et al. 2004).
Introduction (cont.)
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Current research consists of “increasing drought and salt stress
tolerance of Arabidopsis following treatment with βaminobutyric acid” (Jakab et al. 2005).
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Reduced wilting of plant by 50% when treated with β-aminobutyric acid prior to
salt stress application.
Arabidopsis seedlings grown on salt agar develop “enhanced
stress tolerance by detoxifying the active oxygen species more
rapidly” (Tsugane et al. 1999).
Engineering cotton “for higher drought and stress tolerance,
using transgenic plants expressing AtNHX1”(He et al. 2005).
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AtNHX1 is removed from Arabidopsis and transplanted into the cotton plant.
How Do Plants Adapt to Stress
Volatilization
from leaves into
outer atmosphere
Accumulation in
plant tissue
-Mercury
-Selenium
- TCE & PCE
-metabolites
Heavy metals,
Radionuclides,
TCE/PCE,
Rhizospheric
metabolism
-Metals
-Organics
-Radionuclides
metabolites
INORGANIC
- Heavy metals
- Salt & carbon dioxide
- Metabolites (i.e. free radicals
as a result of heavy metals))
ORGANIC
Soil Stabilization
- TCE(Trichloroethylene
)
- PCE (Perchloroethylene
)
- BTEX
Objective and Hypothesis
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Objective-To better understand how salt stresses affect the growth rate of
Arabidopsis thaliana, which can therefore be applied to understand the affect
of salt on the oxygen production and also possible usage for
phytoremediation procedures.
Hypothesis-Yes, salt affects the growth rate of Arabidopsis thaliana in a
negative way.
Null Hypothesis- No, salt does not affect the growth rate of Arabidopsis
thaliana in any way.
Methods and Materials
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Growth and germination methods
will follow the process used by
Patananan & Phillips (2005), with
exception to time length.
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Salt stress applied daily with water
at specified concentration.
At maturation
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Plants removed from soil
Measure length of stem tissue
(cm)
Compare mean length of stressed
stem tissue to mean length of
control stem tissue
Experimental Design Chart
Results (Data Sheet)
Plant Number
Length of
Stem Tissue
(cm)
Control
#1
Control
#2
Control
#3
Average
Length of
Control Tissue
1.83
1.67
1.95
1.82
Stressed Plant
#2
Stressed Plant
#3
Average
Length of
Stressed
Tissue
1.03
0.95
1.15
Plant Number Stressed Plant
#1
Length of
Stem Tissue
(cm)
1.46
Results (cont.)
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Calculated Difference was
determined by taking the
average stem tissue length of
the stressed plants and
dividing it by the average
stem tissue length of the
control group. A 63.2%
decrease in stem length was
found.
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1.15cm/1.82cm X 100 =
63.2%
Discussion
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Results indicate that Arabidopsis responds by a decrease in the
average stem length.
The current research being conducted supports the acceptance
of my hypothesis.
Krep et al. showed a loss of 50% crop yield due to salt stress.
Arabidopsis can be engineered to withstand the salt stress (Teige et al. 2005,
Jakab et al. 2005, and Tsugane et al. 1999).
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The sodium transporter of Arabidopsis can be used to produce transgenic
cotton plants that produce higher yields (He et al. 2005).
Conclusion
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Salt Stress does affect the growth of
Arabidopsis stem length (cm).
The growth is shortened by 63.2% in stressed
plants.
Plants can be engineered to withstand
drought stress. (from Literature)