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Genomics and Applied Biology
, 2012, Vol.3 No.2 8-21
http://gab.sophiapublisher.com
resistance to plant-protection transgenes, such as
Bt
toxins, is to deploy multiple insect-control genes (such
as PIs) with different modes of action in a single plant
(Manyangarirwa et al., 2006). There is evidence that
the combination of PIs with a sublethal-dose
Bt
toxin
has a strong effect on the growth and development of
insects (Zhu et al., 2007). Dunse et al (2010)
coexpressed
Nicotiana alata
proteinase inhibitor
(NaPI) and
Ⅱ
proteinase inhibitors and
Solanum
tuberosum
potato type
Ⅰ
inhibitor (StPin1A). The
combined inhibitory effect of NaPI and StPin1A on
H.
armigera
larval growth in the laboratory was reflected
in the increased yield of cotton bolls in field trials of
transgenic plants expressing both inhibitors.
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In our own study; Bhattacharjee et al (2009) showed
that a thermotolerant monomeric trypsin inhibitor
from
Cocculus hirsutus
(ChTI) caused 74% and
59.53% inhibition of bovine trypsin and
Helicoverpa
gut proteases respectively. The second and third instar
larvae of
H. armigera
fed with ChTI (5000 TIU/mL)
resulted in 84.59 and 58.71% reduction in mean larval
weight respectively. An increase in the larval growth
period was observed in ChTI fed larvae at all instars
and inhibitor fed larvae could not complete their life
cycle (Figure 2; Figure 3). In a recent study by
Alvarez-Alfageme et al (2011) it was observed that
AtSerpin1 (
Arbidopsis thaliana
Serine proteinase
inhibitor) inhibited proteases from all pest and
non-target species assayed. AtSerpin1 supplied in the
artificial diet or by transgenic plants reduced the
growth of
S. littoralis
larvae by 65% and 38%,
respectively, relative to controls. Macedo et al (2010)
suggested that trypsin inhibitor (ApTI) purified from
Adenanthera pavonina
have a potential antimetabolic
effect when ingested by
Anagasta kuehniella
, a
polyphagous pest that feeds on a wide variety of
stored products. Larval and pupal developmental time
of larvae fed on ApTI diet at 1% was significantly
longer; the larval period was extended by 5 days and
pupal period was 10 days longer, therefore delaying
by up to 20 days and resulting in a prolonged period
of development from larva to adult. The percentage of
surviving adults (%S) decreased to 62%. The fourth
instar larvae reared on a diet containing 1% ApTI
showed a decrease in tryptic activity of gut and that no
novel proteolytic form resistant to ApTI was induced.
da Silva et al (2012) showed that 0.1% trypsin
inhibitor (ApTI) have great toxic potential on the
development of
Diatraea saccharalis
, a major
sugarcane pest, causing damage to the stalks of
sugarcane plants larvae. 0.1% ApTI produced
approximately 67% and 50% decreases in weight and
survival larval, respectively. The level of trypsin was
significantly decreased (ca. 55%) in the midgut of
larvae reared on a diet containing 0.05% ApTI and the
trypsin activity in ApTI-fed larvae demonstrated
sensitivity to ApTI.
Figure 3
Effect of ChTI on growth of
Helicoverpa and
Spodoptera
larvae
Note: The second star larvae were fed with artificial diet containing
ChTI (5000 TIU) and control on same diet without ChTI
4.2 Proteinase inhibitor-antifungal and antibacterial
property
Proteinase inhibitors in plants are able to suppress
enzymatic activity of phytopathogenic microorganisms.
Trypsin and chymotrypsin inhibitors of plant origin
were shown to suppress activity of proteinases secreted
by
Fusariumsolani
(Mosolov et al., 1976). Heat stable
antimicrobial peptide, Potide G, completely suppress
the proteolytic activity of trypsin, chymotrypsin and
papain, in addition to growth inhibition of variety of
bacterial and fungal strains (Kim et al., 2006). In
tomato and potato tubers infected with the oomycete
fungus,
P. infestans
, increase in trypsin and
chymotrypsin inhibitor content was observed, which
correlated with resistance to pathogen (Valueva et al.,
1998, 2003). Mendieta et al (2004) reported that