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Bt Research 2015, Vol.6 No.1 1-8
ISSN 1925-1939
http://bt.biopublisher.ca
4
Table 2. Gene content of
B. thuringiensis
and
S. frugiperda
larval mortality.
Isolates
Genes
Mortality (%)
cry1Fa
vip3Aa
Chi
I_10
X
X
X
94.55 ±1.50
a
I_17
X
X
X
90.65 ±4.60
a
I_9
X
X
X
89.07 ±2.71
a
I_15
X
X
X
87.50 ±6.63
ab
I_13
X
X
X
86.72 ±1.97
abc
I_14
X
X
X
85.17 ±1.50
abc
I_16
X
X
X
84.40 ±5.10
abc
I_1
X
X
X
84.40 ±7.10
abc
I_2
X
X
X
81.25 ±4.60
abc
I_6
X
X
-
80.47 ±1.50
abc
I_18
X
X
X
80.47 ±2.34
abc
I_12
X
X
X
73.42 ±2.71
bcd
HD125
-
X
-
71.87 ±8.74
cd
I_7
-
X
X
61.72 ±9.99
d
I_11
X
X
X
60.15 ±13.03
d
alesti
-
-
X
41.42 ±7.14
e
I_8
-
X
-
28.92 ±1.50
ef
I_3
X
-
-
16.42 ±6.17
fg
I_4
X
-
X
12.52 ±3.83
gh
aizawai HD137
X
-
-
10.95 ±4.69
gh
I_5
-
-
X
2.32 ±0.78
gh
tenebrionis#
-
-
-
0
h
Check
-
-
-
0
h
X indicates the gene(s) were amplified whereas – indicates lack of the gene(s)
the chitinases exhibited the potential to increase the
toxicity of the bacterium for the control of
Spodoptera
exigua
(Hubner, 1808) (Lepidoptera: Noctuidae)
larvae. Among the 70 strains tested, 38 exhibited
toxicity, indicating their potential to be applied
synergistically with other
B. thuringiensis
crystal
proteins. Thus, the majority of isolates tested in this
work were confirmed to produce chitinase, and the
isolates containing all three genes caused the highest
mortality, which suggests a possible synergy among
the genes. The chitinase protein may have caused the
partial digestion of the insect’s peritrophic membrane,
which may have facilitated the action of the Cry1Fa
and Vip3A proteins.
Multiple binding sites for Cry1 toxins are present in
many insects (Ferré et al., 1991; Luo et al., 1999;
Hernández-Martínez et al., 2014). The results obtained
by Luo et al. (1999) demonstrated that there are at
least two union sites with high affinity for the Cry1
toxin in
S. frugiperda
. The work performed by Sena et
al. (2009) complemented the results of Luo et al.
(1999) by demonstrating a union between Cry1Ab and
Cry1Fa in
S. frugiperda
which reinforced the idea of
competition for the sole union site in the gut. In
relation to interactions with
vip3
gene, this work
evaluated the competition between the
cry1
and
vip3
genes in
S. frugiperda
, demonstrating that it is
possible to combine
vip
with
cry
. These isolates could