www.czu.cz ; www.raupp.info

A plant that cleans toxic substances from soils and turns the matter into
nutraceutical?does it sound to good to be true? Thanks to a team at the
Center for Plant Environmental Stress Physiology in West Lafayette it may
soon become reality, February 2005 by Flora Mauch, Checkbiotech .

Phytoremediation is an emerging science, which when translated means using
plants to remove contaminants from soils, thus cleansing the environment. In
many cases, researches use the root system of a given plant as a huge,
subterranean sponge, which soaks up impurities such as crude oil or heavy
metals.

Another element that can be absorbed by plants is selenium. Selenium is a
metal found in natural deposits and is an essential nutrient at low levels.
It is known that selenium accumulates in living tissues. When people are
exposed to above normal doses for relatively short periods of time, it has
been found to cause health effects such as, damage to the peripheral nervous
system, fatigue and irritability.

Selenium compounds are released in the air during the combustion of coal and
petroleum fuels, during the smelting and refining of other metals or can be
the result of natural geological processes. Sites rich in selenium are
situated for example in soils in the high plains of northern Nebraska and
the Dakotas.

Interestingly, there is a selenium accumulating plant called Astragalus
bisulcatus, which has the ability to turn toxic selenium into a compound
with cancer preventing qualities called, Methylselenocysteine (MeSeCys).
While studying A. bisulcatus, Dr. Salt?s research team at the Center for
Plant Environmental Stress Physiology at West Lafayette, studied an enzyme
called selenocysteine methyltransferase (SMT) that provided A. bisulcatus
with the ability to convert selenium into MeSeCys.

Recognizing the value of this enzyme, the researchers in West Lafayette
characterized its properties, in order to develop plants not only with
ability to cleanse selenium, but also an enhanced ability to biosynthesize
MeSeCys. In this way the research team expected to obtain an efficient plant
based source of the anti-carcinogenic compound.

Ideally, Dr. Salt needed to have a plant that would be edible, grow fast and
produce MeSeCys when growing in the presence of selenium. Since, A.
bisulcatus only could grow relatively slow and contains compounds that are
toxic to humans, Dr. Salt?s group needed to search elsewhere.

Hence, Dr. Salt?s lab is in the process of generating genetically modified
mustard plants, expressing the A. bisulcatus selenocysteine
methyltransferase (SMT) gene. According to Dr. Ellis, a researcher in Dr.
Salt?s lab, a first step towards this goal has already been taken.

?While our SMT transgenics have increased selenium tolerance and
accumulation when grown on selenite, they have no increase in selenium
tolerance or accumulation when grown on selenate. These plants are the first
step to producing plants that could be used for phytoremediation.?

Dr. Ellis continued with, ?We are currently conducting experiments with the
goal of understanding how A. bisulcatus selenium hyperaccumulators reduce
large amounts of selenate. If successful, we can use this knowledge to
create transgenic plants that could be potentially used for selenium
phytoremediation.?

The research team of Dr. Salt envisions the genetically engineered mustard
plants being used as a nutraceutical and offered to people in pill form.
However, Dr. Ellis cautions, ?While methylselenocysteine can potentially be
beneficial at some doses, consuming too much can be toxic.?

However, we can look forward to a new type of phytoremediation that will
provide not only a cleaner environment, but also be of great use for human
health.

[www.checkbiotech.org];
subtopic_id=2&doc_id=9575

------------------------------------------
Posted to Phorum via PhorumMail