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Rate-limiting steps in selenium assimilation and volatilization by indian mustard
de Souza MP1, Pilon-Smits, Lytle
1Department of Plant and Microbial Biology, 111 Koshland Hall, University of California, Berkeley, California 94720, USA.
Plant Physiology
|August 14, 1998
Summary
Selenium phytoremediation using Indian mustard shows that volatilization rates differ between selenate and selenite. Selenite volatilization is faster, limited by uptake and conversion, while selenate volatilization is slower, limited by reduction and translocation.
Area of Science:
- Environmental Science
- Biotechnology
- Plant Science
Background:
- Selenium (Se) accumulation by plants and volatilization to dimethylselenide offers a promising phytoremediation strategy.
- Understanding the rate-limiting steps in Se volatilization is crucial for optimizing this technology.
Purpose of the Study:
- To determine the rate-limiting steps in selenium volatilization from selenate and selenite using Indian mustard (Brassica juncea).
- To investigate the kinetics of Se accumulation and volatilization under varying time and concentration conditions.
Main Methods:
- Kinetic studies of Se uptake, translocation, and volatilization in Indian mustard.
- Analysis of Se speciation using X-ray absorption spectroscopy.
- Correlation of volatilization rates with root Se concentrations.
Main Results:
- Selenate uptake was twice as fast as selenite uptake, but selenate was rapidly translocated to shoots.
- Se volatilization rates were 2-3 times higher for selenite compared to selenate.
- Selenite-supplied plants accumulated organic Se (selenomethionine), while selenate-supplied plants accumulated selenate.
- Volatilization rates correlated linearly with external Se concentration (up to 20 µM) and root Se concentrations.
Conclusions:
- Selenate volatilization is limited by the rate of selenate reduction and Se availability in roots (influenced by uptake/translocation).
- Selenite volatilization is likely limited by selenite uptake and the conversion of selenomethionine to dimethylselenide.
