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

1
Effects of salt stress on the stem growth of
Arabidopsis thaliana.

• Jacob Phillips
• Undergraduate Student
• Department of Biology
• Tennessee Technological University
• Cookeville, Tennessee 38505

2
Introduction

• Increasing soil salinity is imposing stress on
  biological conditions for many organisms.
• 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.
• 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
  stressplants overexpressing MKK2 showed
  increased salt and freezing tolerance. (Teige et
  al. 2004).

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Introduction (cont.)

• Current research consists of increasing drought
  and salt stress tolerance of Arabidopsis
  following treatment with ß-aminobutyric acid
  (Jakab et al. 2005).
• Reduced wilting of plant by 50 when treated with
  ß-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).
• AtNHX1 is removed from Arabidopsis and
  transplanted into the cotton plant.

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How Do Plants Adapt to Stress

• Volatilization from leaves into outer atmosphere
• Mercury
• Selenium
• TCE PCE
• metabolites

Accumulation in plant tissue
Heavy metals, Radionuclides, TCE/PCE, metabolites

• Rhizospheric metabolism
• Metals
• Organics
• Radionuclides

INORGANIC - Heavy metals - Salt carbon
dioxide - Metabolites (i.e. free radicals as a
result of heavy metals))

• ORGANIC
• - TCE(Trichloroethylene )
• PCE (Perchloroethylene )
• - BTEX

Soil Stabilization
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Objective and Hypothesis

• 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.

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Methods and Materials

• Growth and germination methods will follow the
  process used by Patananan Phillips (2005), with
  exception to time length.
• Salt stress applied daily with water at specified
  concentration.
• At maturation
• 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

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Results (Data Sheet)
Plant Number Control 1 Control 2 Control 3 Average Length of Control Tissue
Length of Stem Tissue (cm) 1.83 1.67 1.95 1.82
Plant Number Stressed Plant 1 Stressed Plant 2 Stressed Plant 3 Average Length of Stressed Tissue
Length of Stem Tissue (cm) 1.46 1.03 0.95 1.15
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Results (cont.)

• 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.
• 1.15cm/1.82cm X 100 63.2

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Discussion

• 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).
• The sodium transporter of Arabidopsis can be used
  to produce transgenic cotton plants that produce
  higher yields (He et al. 2005).

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Conclusion

1. Salt Stress does affect the growth of Arabidopsis
   stem length (cm).
2. The growth is shortened by 63.2 in stressed
   plants.
3. Plants can be engineered to withstand drought
   stress. (from Literature)