Biomedical Engineering Reference
In-Depth Information
plants expressing TvGST gene were exposed to different concentrations
of Cd, they were found to be more tolerant compared to wild type plants,
with transgenic plants showing lower levels of lipid peroxidation. Levels of
different antioxidant enzymes such as glutathione transferase, superoxide
dismutase, ascorbate peroxidase, guiacol peroxidase and catalase
showed enhanced levels in transgenic plants expressing TvGST compared
to control plants, when exposed to Cd. Cadmium accumulation in the
plant biomass in transgenic plants were similar or lower than wild-type
plants. The same plants were also tolerant to the polyaromatic hydrocarbon
anthracene and the transgenic plants not only tolerated high levels of this
toxic chemical, they also degraded it to non-toxic naphthalene derivatives
(Dixit et al. 2011b).
CONCLUSION
The evidences provided in this article clearly demonstrate the role
of various genes and gene products in the interactions of
Trichoderma
spp. with plant pathogenic fungi and plants. Most of these are isolated
studies with single genes as no genome sequences of the mycoparasitic
species of
Trichoderma
were available. This has changed now with the
recent publication (Kubicek et al. 2011) of whole genome sequencing
of two mycoparasites (
T. virens
and
T. atroviride
:
http://genome.jgi-psf.
org/TriviGv29_8_2 /TriviGv29_8_2.home.html
and http://genome.jgi-
psf.org/Triat2/Triat2.home.html, respectively). This will facilitate the
transcriptomics, proteomics and metabolomics data being made available
and thus many candidate genes for strain improvement of
Trichoderma
spp. would be identifi ed and used. A few examples that have emerged
recently are: improved thermotolerance of
T. harzianum
by heterologous
expression of of
hsp23
, a small heat shock protein gene from
T. virens
(Montero-Barientos et al. 2007b), homologous over-expression of
hsp70
in
T. harzianum
for enhanced tolerance to heat shock, oxidative stress, osmotic
stress and salt stress (Montero-Barrientos et al. 2008), overexpression of
an endochitinase gene
ThEn-42
in
T. atroviride
for enhanced antagonist
action against pathogenic fungi (Deng et al. 2007) and beta glucanases for
improved biocontrol potential of
T. virens
(Djonovic et al. 2007b).
Reference
Altomare, C., W.A. Norvell, T. Bjorkman G.E. Harman. 1999. Solubilization
of phosphates and micronutrients by the plant-growth-promoting and
biocontrol fungus
Trichoderma
harzianum
Rifai 1295-22.
Appl. Environ.
Microbiol
.
65:
2926-2933.
