OsGSTL1 is a glutathione transferase lambda class gene from rice (Oryza sativa L.).
Over-expression of OsGSTL1 in rice enhanced tolerance to chlorsulfuron and glyphosate.
[26].
Benekos et al [5] have over-expressed a soybean GmGSTU4 in tobacco and found that
the transgenic plants had increased tolerance to the diphenyl ether herbicides fluorodifen and
oxyfluorfen (200μΜ) and the chloroacetanilide alachlor (7.5 mg/L). The tolerance was
expressed as reduced electrolyte leakage when compared to wild -type plants.
As described above, GSTs are enzymes able to enhance plant tolerance to herbicides. The
first transgenic herbicide crops were introduced in the United States in 1996. These were
soybean plants resistant to glyphosate. Later, cotton and maize transgenic herbicide resistant
plants were developed. Currently, almost 74 million hectares in 13 countries are being
cultivated with five different genetically engineered herbicide tolerant crop species [27]. In
order to develop herbicide tolerant plants, safe for both the consumer and the environment,
the genes introduced into the plants must lead to a complete detoxification of the herbicide.
However, the formation of herbicide conjugates with GSH fundamentally alters their
physicochemical properties, rendering the compounds more polar and unable to freely diffuse
across cellular compartments or translocate throughout the symplast. Furthermore, GSHherbicide
conjugates are usually the target of further metabolism and can be accepted by
energized carriers for their transport out of the cytosol. In order to develop and commercialise
herbicide resistant plant species, toxicity studies must be performed [28]