Basic HTML Version
Genomics and Applied Biology
, 2012, Vol.3 No.2 8-21
http://gab.sophiapublisher.com
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pigeon pea cultivars and wild genotypes, resistant and
susceptible to insect-pests and pathogens, for the
presence of proteinase inhibitors against Helicoverpa
armigera gut proteinases (HGPs). PIs from pigeonpea
cultivars showed complete inhibition of trypsin and
chymotrypsin, and moderately towards HGPs. PIs of
wild relatives showed stronger inhibition with HGPs.
Telang et al (2003) purified bitter gourd (
Momordica
charantia
L.) seed proteinase inhibitors (BGPIs) that
strongly inhibit HGPs. Electrophoretic analysis
revealed the presence of two major proteins (BGPI-1
and-2) and two minor proteins (BGPI-3 and-4) having
inhibitory activity against trypsin and HGPs. BGPIs
inhibited proteolytic activity of larvae fed on different
host plants, artificial diet with or without PIs
supplementation and proteinases excreted in fecal
matter from respective samples. BGPIs were found to
retard growth and development of
Helicoverpa
armigera
and
Spodoptera litura
. Reports indicate that
BGPIs mediated inhibition of insect gut proteinases
directly affect fertility and fecundity of
H. armigera
and
S. litura
. Patricia et al (2003) used bioassays to
investigate the effect of Bowman Birk and kunitz
-type soybean trypsin inhibitor on growth pattern of
Diatraea saccharalis moth using two diets- Diet 1 was
less nutritious, with low protein content; and reduced
minerals and essential aminoacids (cysteine, lysine
and methionine) content while Diet 2 was richer and
more complete. Food intake and utilization; larval
development and mortality were monitored. When PI
was supplemented, larval development was
significantly altered in larvae fed with diet1, with
reduced trypsin-like activity of midgut enzymes. Diet
2 fed larvae also showed reduced level of trypsin-like
activity but it was less marked than diet 1. Similar
feeding experiment was done with subabul high and
low molecular weight trypsin inhibitor (HSTI, LSTI)
using artificial diet, chickpea seeds and leaves. Larvae
fed with artificial diet showed reduction in larval
weight up to 21% (HSTI) and 43% (LSTI). However,
larvae fed on seeds showed significant reduction in
weight, 52.4% (HSTI) and 60.3% (LSTI), suggesting
the diet also play vital role on the effectiveness of the
inhibitors on larval growth and development (Bhavani
et al., 2007). Franco et al (2004) suggested that
SKTI can be an effective in developing transgenic
plants against the cotton boll weevil,
Anthonomus
grandis
. Cotton boll weevil gut digestive system
contains serine proteinases.
In vitro
assay showed
that SKTI inhibit these enzymes. Neonate larvae
reared on an artificial diet containing SKTI showed
reduction in larval weight of up to 64% and caused
mortality and severe deformities of larvae, pupae
and adult insects.
Oryza sativa
chymotrypsin
inhibitor (OCPI1) transgenic positive plants
showed higher grain yield and seed setting rate than
the wild type and control under the severe drought
stress conditions, whereas the potential yield of
transgenic plants under normal growth conditions was
not affected. Chymotrypsin- inhibitor activity assay
from positive transgenic plants showed stronger
inhibition. The decrease of total proteins in transgenic
plants is less than the wild type under drought stress
(Huang et al., 2007). The defensive role of PIs is
based on their inhibitory activities towards proteolytic
enzymes of insect gut and phytopathogens resulting
either in a critical shortage of essential amino acids
(Hilder et al., 1993; Jongsma and Bolter, 1997) or
interfering with metabolic processes, such as the
proteolytic activation of enzymes, molting of insects,
or replication of viruses (Gutierrez-Campos et al.,
1999). Direct evidence for the involvement of PIs in
the plant defense system has come from studies on
transgenic plants. Transgenic plants expressing PIs
have been produced in the last two decades and tested
for enhanced defense capacities, particularly against
insect-pests (De Leo et al., 2002). Expression of
cowpea trypsin inhibitor (CpTI) in transgenic tobacco
was shown for the first time to confer resistance to
feeding by tobacco budworm
Heliothis virescens
(Hilder et al., 1987). Plant proteinase inhibitors are
known to confer natural protection against nematode
attack (Atkinson et al., 2003; Cai et al., 2003;
McPherson and Harrison, 2001). Nematode control
with PIs expressed in transgenic tomato (Urwin et al.,
1995),
Arabidopsis thaliana
(Urwin et al., 2000), and
rice (Vain et al., 1998) has been well documented
(Hepher and Atkinson, 1992).
PIs have the potential to enhance the current Bt toxin
technology because they target a broader range of
pests, including nematodes and fungi (Hilder and
Boulter, 1999). There is a major concern that the
effectiveness of
Bt
will be negated if field-evolved
Bt
resistance (Tabashnik et al., 2009) becomes a more
widespread problem. A proposed management
strategy for delaying insects’ development of