Pollution is a worldwide problem. Traditional methods of pollution management are costly, time consuming, and are potentially environmentally invasive. Phytoremediation is an alternative method of managing environmental contaminants such as selenium (Se). Phytoremediation is a mechanism that utilizes plants to help remediate contaminated areas. To reduce excess Se from the soil, Se can be volatized by plants by phytoremediation or stored in the plants’ shoots and leaves. Additionally, the shoots and leaves can later be used in fertilizers, or as nutritional supplements to help combat Se deficiency. Certain plants, called hyperaccumulators, can withstand up to 15, 000 mg/kg dry weight of selenium. These plants can play a vital role in phytoremediation of Se. Stanleya pinnata is one of the few plants capable of hyperaccumulating Se. S. pinnata has high tolerance of boron, heat, and salinity, making it an good candidate for phytoremediation studies. While there have been studies using S. pinnata grown in synthetic media in laboratory settings, germination and growing conditions for axenic S. pinnata have not been optimized. Optimization of germination and early growth for axenic S. pinnata in culture conditions would prove useful in future phytoremediation studies and applications. Stanleya pinnata has a 45-day cold moist stratification period for seed germination. However, reducing or eliminating this dormancy period could allow for more research to be carried out in shorter periods of time. This may also reduce the time for pollution clean-up by shortening the time for early plant growth. The goal of this study was to optimize growing conditions for axenic S. pinnata using a plant tissue culture approach. Experiments focused on establishing an artificial environment for optimized S. pinnata seed germination and early growth. The hormone gibberellic acid (GA) was used to eliminate the cold, moist stratification period of S. pinnata. Other conditions that were examined include media type and medium supplemented with selenium. The results support the use of synthetic media for germination and early growth of axenic S. pinnata. Seed treatment with (0, 250, 500, or 1,000 mg/L) GA prior to placement in media did not increase the number of germinated seeds between the different concentrations tested. However, GA concentration is useful for reducing germination time and bypassing seed dormancy. The media type with best combination of germination percentage, seedling number, and biomass production was agar-solidified MS media. While literature suggests that Se may be beneficial to plant development in low levels, the data showed the addition of Se in 0, 25, 50, 75, and 100 µM did not seem to improve S. pinnata seed germination or seedling growth. However, late growth and development was not studied and the use of Se in media may impact growth and development at later stages. This experiment provides insight on germination and early growth of axenic S. pinnata. Successful axenic S. pinnata growth will allow for comparisons of microbial symbiont Se uptake and the plant itself in Se phytoremediation experiments. Future studies should focus on further optimization of growing conditions, especially the later stages of growth and development for S. pinnata. Future studies could also examine microbial symbionts with hyperaccumulators and determine which microbial symbionts, if any, are the most effective at aiding with Se hyperaccumulation.
|Commitee:||Lin, Zhi-Qing, Schulz, Kurt|
|School:||Southern Illinois University at Edwardsville|
|School Location:||United States -- Illinois|
|Source:||MAI 57/01M(E), Masters Abstracts International|
|Keywords:||Axenic, Candidate, Germination, Optimization, Phytoremediation, Pinnata, Selenium, Stanleya|
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