Contents - Faperta

Genetic Transformation of Crops for Resistance to Insect Pests 223
(100% mortality), and fi eld trials in Egypt (99 to 100% undamaged tubers). Reduced feeding
by Colorado potato beetle fi rst instars was also observed in detached-leaf bioassays
(80 to 90% reduction). Field trials in the United States demonstrated that the performance
of these transgenic lines was comparable to “Spunta.” These Bt-cry5 transgenic potato
plants with high potato tuber moth resistance can be used in integrated pest management
programs.
Vegetables
Expression of Bt genes in tomato was one of the fi rst examples of genetically modifi ed
plants with resistance to insects (Fischhoff et al., 1987). Tomato plants expressing cry1Ab
and cry1Ac genes are effective against the lepidopteran insects (Delannay et al., 1989; Van
der Salm et al., 1994). Expression of cry1Ac gene in tomato is highly effective against
H. armigera (Mandaokar et al., 2000). The transgenic tomato plants expressing cry1Ab suffered
signifi cantly lower damage by H. armigera than the nontransgenic control plants in
the laboratory, greenhouse, and fi eld. The Bt-transgenic plants caused 100% mortality of
H. armigera larvae (Kumar and Kumar, 2004). Transformed brinjal plants have also shown
insecticidal activity against the fruit borer, Leucinodes orbonalis Guen. (Kumar et al., 1998).
Synthetic cry1C gene introduced into broccoli, B. oleracea subsp. italica, provides protection
not only from the susceptible diamondback moth, P. xylostella larvae, but also from
diamondback moth selected for moderate levels of resistance to Cry1C (Cao et al., 1999).
Synthetic cryIAb gene inserted into broccoli cultivar cv. Pusa Broccoli KTS-1 (Viswakarma
et al., 2004) and cryIAb in cabbage (Bhattacharya et al., 2002), and cry1Ab or cry1Ac genes
in Brassica campestris L. subsp. parachinensis (Xiang et al., 2000) have shown resistance to
P. xylostella. Transgenic caulifl ower plants transformed with synthetic cry9Aa gene have
also shown high levels of activity against P. xylostella (Kuvshinov et al., 2001). Transgenic
broccoli containing cry1C is resistant to the cabbage looper, T. ni, and cabbage butterfl y,
Pieris rapae (L.). L.B. Lin et al. (2001) observed a mortality of 94.4% in P. rapae larvae reared
in the laboratory on transgenic rapeseed leaves as compared with 15.0% mortality on the
nontransgenic cultivar, Xiangyou 16. Under fi eld conditions, the larval mortality was 46.5%
on the transgenic rapeseed compared to 21.3% mortality on the control plots.
Fruits and Forest Trees
Walnut, Juglans regia L., trees expressing a modifi ed cry1Ac gene have been found to be
effective against the fi rst instar codling moth, Cydia pomonella (L.) larvae (Leslie et al., 2001).
Production of Cry1Ac protein was confi rmed by Western analysis. There was a good correspondence
between GUS activity, protein expression, and insect mortality. Alteration of
the wild-type nucleic acid sequence was important in increasing the bioeffi cacy. Dandekar
et al. (2002) reported that apple and walnut transformed with Bt genes conferred enhanced
resistance to the codling moth, C. pomonella and other lepidopteran insects.
Ornamentals
Shinoyama et al. (2003) introduced a modifi ed cry1Ab gene into chrysanthemum,
Chrysanthemum morifolium syn. D. morifolium (Ramat). The level of accumulation of Cry1Ab
protein ranged from 10.5 to 80 ng per 50 μg of total soluble protein (0.021 to 0.16% of the
total protein). All the larvae of H. armigera died during the fi rst instar on the leaves of transformed
lines with expression level of 47.6 ng per 50 μg of total protein.