Prosopis juliflora is a drought-tolerant tree species of Fabaceae, which is used as a model
plant system in order to identify genes involved in abiotic stress tolerance, like the PjGSTU1
gene. Transgenic tobacco lines carrying a PjGSTU1 gene survived under conditions of 15%
PEG stress, which acts as a drought stress, compared to wild-type plants [41].
In another study, a novel GST gene from Limonium bicolor (LbGST1) has been cloned
and over-expressed in tobacco. Transgenic LbGST1 tobacco lines exhibited both GST and
glutathione peroxidase activities. In addition, superoxide dismutase, peroxidase (POD), and
catalase activities in transgenic plants were significantly higher compared to wild-type plants,
particularly when grown under salt stress. LbGST1 was found to be localised in the nucleus,
suggesting a possible role in mediating certain physiological pathways or protecting the DNA
from oxidative damage [42].
Tobacco plants over-expressing the GsGST gene form Glycin soja (a soybean species
which can survive in high salt and drought conditions) showed enhanced dehydration
tolerance and T2 seedlings showed higher tolerance to salt and mannitol than wild-type plants,
during the seedling stage, as measured by longer root length and less growth retardation [43].
Arabidopsis thaliana has been sequenced [44] and thus far 54 GST genes have been
identified [45]. Gong et al [46] investigated the “in vivo” function of the mustard gene
BjGSTF2. The transgenic plants were tolerant to HgCl2 and paraquat and flowered two days
earlier compared to wild–type. Moreover, transgenic plants over-expressing the GST gene
were highly regenerative, suggesting that GST plays a role in plant growth and development
in vivo and shoot regeneration in vitro.
Finally, transgenic tobacco and tomato plants over-expressing a specific soybean
GmGSTU4 isoenzyme have been created in our laboratory and show enhanced tolerance to
abiotic stresses such as drought and salt (unpublished results) (Figures 2 and 3).