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 stress…plants overexpressing MKK2 showed increased salt and freezing tolerance.” (Teige et al. 2004).

3. Introduction (cont.) • Current research consists of “increasing drought and salt stress tolerance of Arabidopsis following treatment with β-aminobutyric acid” (Jakab et al. 2005). • 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). • AtNHX1 is removed from Arabidopsis and transplanted into the cotton plant.

4. 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

5. 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.

6. 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

7. Results (Data Sheet)

8. 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%

9. 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).

10. Conclusion • 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)