1. Afifa hameed
Roll no 11011514-031
Sec G
Entomology
UOG

2. Transgenic plants for insect
resistance (review)
authors: Lise Jouanin, Michel Bonade´-
Bottino , Ce´cile Girard , Gil Morrot ,Marc
Giband(2007)
journal: Elsevier science
,
Received 11 September 2006
revised 17 October
accepted 20 October 2007
Volume 72

3. abstract
 Genetic engineering insect resistance
plants
 Two approaches in this paper
 1st…delta endotoxin sequence of gene from
B. thuringensis
 2nd ..plant derived genes……enzymes
inhibitors and lectins.

4. introduction
 Loss of agriculture 37% pest and
dieases.
 13% insects
 Use of chemicals is harmful for plants and
also for other animals and birds..
 Future planning ……environment friendly
methods of insect resistance by breeding
techniques.e.g somatic hybrid potato have
resistance against potato beetle..
 ( J. Cheng et all,2002)

5.  Delta endotoxin from B.thuringensis…
 1996 first time insecticidal plant in market.
1) Use of Bacillus thuringiensis d-endotoxins
The B. thuringiensis toxins: first discover from
silkworm population….1902 (Japan)
1911 from flour moth population..(Germany)
 They are gram +ve bacteria produced crystalline inclusion
during sporulation.
Crystalline inclusion…………delta endotoxin….
Several crystalline proteins formed by B.thuringenisis ..
90 genes isolated from it that form protoxin..
(M. Mazier et all 2002)

6.  First identify proteins cryI, cryII, cryIII….host
specific
 E.g cry I……Lepidoptera
 Cry II……..coleoptera
(H.R. Whiteley,2000)
Delta endotoxin solublized insect mid gut,
activate by gut proteases..cleave protein into
smaller polypeptide(toxin)….toxin binds to
epithelial surface of gut cells and destroys cells
and insect dia.
(B.H. Knowles et all, 2003)

8. Transgenic plants
 Safe method….entire plant protect from insects and those
parts where spray not reached.
 First transfer of B.thuringensis genes in
tobacco,tomato,1987..
 Then cotton, maize, rice ……..Lepidoptera as main target.
(M. Vaeck et all,2003)
 Several proteins constructed as
cryIA(a),cryIA(b),cryIa(c)… for lepidoptera.
 cryIC,cryIIIA…..coleoptera e.g (colorado potato beetle)
( F.J. Perlak,2001)

9. First field trial of expressing this bacterial gene
in 1986 with tobacco on small scale then on
large scale in US. (A.F. Krattiger et
all,2005)
1995 the first transgenic crops cryIA(b) toxin
expressed in corn.
Cotton cryA( c)
Potato cryIIIA
1996…..1.2 million ha B.thuringensis
transgenic crops in US. (M.
Peferoen et all,2004)
 New methods of screening (antibody PCR) now used for
more identification of toxin in B.turingensis..

11. 2) Use of plant-derived genes
 Plants derived proteins protects plants
from insect attack..importantly protect
from those insect that attack on
vulnerable parts as seeds.
 Different proteins as proteases
inhibitors ,lectins interfere with growth
and development of larvae of insects
and cause death of them.
 (C.A. Ryan,2000)

12. Proteinase inhibitors
 4 types….inhibiting serine,cystein,metallo or
aspartyl proteases.
 Protease inhibitor small size…serine has two active
sites….trypsin…chymotrypsin …
 (G.R. Reeck et all,2002)
 Serine is abundant in seeds and storage tissues.
 PI..interfere with insect larval growth.
 First transgenic gene isolated from cowpea encoded
for trypsin/ trypsin inhibitor CPTI (protein against
field and storage pests).
 Plant resistance against lepidoptera…….serine PI
originate from different sources..

14.  Fewer cysteins are known and their
action on insects.
 Gene encoding a cystein PI isolated
from rice introduced in
tobacco,potato,poplar,oil seed rape
and cotto.only result of toxicity against
beetle feeding on poplar.
 (J.C. Leple et all 2005)
 Some insects now have resistance against PI so
new methods and techniques trying to find for this
problem.

15. a-Amylase inhibitors
 Common bean Phaseolus vulgaris (kidney
bean) have seed protein PHA.E and L
arcelin and a.amylase (a.AI).
 PHA.E and L arcelin are
lectins…..agglutinin activity.
 a.amylase defense against insects.
 A.amylase from common bean
resistance to bruchid beetle
(Bruchus pisorum).

16.  Transfer of a.amylase gene to azuki
bean protect it from 3 species of
bruchids.
 Drawback: in nature Acnathoscelides
obtectus and Zabrotes subfasciatus feed
on those plants that produced
a.amylase.having serine proteases that
able to cleave a.amylase..
 (M. Ishimoto,1996)

17. Lectins
 Carbohydrate binding proteins….in seeds and
storage tissues.
 Toxic to birds and mammals to some extent.
 Toxicity against insects have been observed.
however exact mechanism not known .
 (T.M. Czapla et all,2003)
 Lectins bind to glycoconjugates located in mid
gut of insects.
 Lectins from garlic and snowdrop are toxic to
insects.
 Tobacco plants expressing a pea lectin were
shown to be toxic to the Lepidoptera Heliothis

18.  potato plants expressing the snowdrop lectin
(GNA) were toxic to the Lepidoptera Lacanobia
oleracea.
 Most work involving lectins has
 focused on the obtention of aphid-resistant
plants.
 The expression of the GNA in tobacco resulted
in
 added protection against the aphid Myzus
persicae
 (V.A. Hilder et all.2000)

19. Myzus persicae
Heliothis
virescens..

20. Chitinases
 Alkaloids…..antifeedant to insects
 Tryptophan decarboxylase from Catharanthus
roseus allows the synthesis of tryptamine and
tryptamine-based alkaloids in tobacco caused
the death of whitefly pupae.
 (J.C. Thomas et all,2000)
 The expression of a bean chitinase in potato
causes no deleterious effect to a Lepidoptera,
Lacanobia oleracea, but reduces fecondity of
the aphid A. solani.
 (A.M.R. Gatehouse)

21. New insecticidal genes
 Struggle for identification of new insecticidal
products.
 Usually plant samples…….tropical plants and
bacteria of different physiology stages.
 B.thuringensis produced a protein Vip3A against
Lepidoptera e.g. cutworms (corn pest).
 (J.J. Estruch et all,2003)
 Streptomyces secretes cholesterol oxydase
against boll weevil.
(H.-J. Cho et all,2005)
 These are new interesting sources for engineering
resistance.

22. conclusions:
 Engineering crops with insecticidal protein genes
is one of first major projects in plant
biotechnology.
 The value of such technology to the Seed
biotechnology industry, the farmer, the
environment and the consumer is obvious.
 Insect-resistant
 crops could reduce the cost, time and
 efforts spent protecting crops from insects.
 Environment friendly…
 Continuing
 research on new sources of resistance is
essential
 for the long term control of insect pests.

23.  Continuing research on new sources of
resistance is essential for the long term
control of insect pests.
 In a first step, studies on the expression and
potential of the new insecticidal genes can be
performed in model plants such as tobacco.
 In a second step, the selected gene(s) must
be introduced into the target crop.
 In another step, field trials must be performed
in different locations and for several years.
(M.O. Santos et all,2006)