Transgenic broccoli expressing aBacillus thuringiensis insecticidal crystal protein: Implications for pest resistance management strategies

Metz, Timothy D.; Roush, Richard T.; Tang, Juliet D.; Shelton, Anthony M.; Earle, Elizabeth D.

doi:10.1007/bf01248408

Cited by 123 publications

(70 citation statements)

References 45 publications

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“…Survival to maturity has been reported for resistant strains of diamondback moth on B. thu- ringiensis-transgenic broccoli and B. thuringiensis-transgenic canola (17,22,38) and for tobacco budworm (Heliothis virescens) and pink bollworm (Pectinophora gossypiella) on B. thuringiensis-transgenic cotton (6,13). However, in all these reports the resistant strains did not develop directly from selection on B. thuringiensis-transgenic crops.…”

Section: Discussionmentioning

confidence: 88%

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Development and Characterization of Diamondback Moth Resistance to Transgenic Broccoli Expressing High Levels of Cry1C

Zhao

Collins

Tang

et al. 2000

Appl Environ Microbiol

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116

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A field-collected colony of the diamondback moth, Plutella xylostella, had 31-fold resistance to Cry1C protoxin of Bacillus thuringiensis. After 24 generations of selection with Cry1C protoxin and transgenic broccoli expressing a Cry1C protein, the resistance that developed was high enough that neonates of the resistant strain could complete their entire life cycle on transgenic broccoli expressing high levels of Cry1C. After 26 generations of selection, the resistance ratios of this strain to Cry1C protoxin were 12,400-and 63,100-fold, respectively, for the neonates and second instars by a leaf dip assay. The resistance remained stable until generation 38 (G38) under continuous selection but decreased to 235-fold at G38 when selection ceased at G28. The Cry1C resistance in this strain was seen to be inherited as an autosomal and incompletely recessive factor or factors when evaluated using a leaf dip assay and recessive when evaluated using Cry1C transgenic broccoli. Saturable binding of 125 I-Cry1C was found with brush border membrane vesicles (BBMV) from both susceptible and Cry1C-resistant strains. Significant differences in Cry1C binding to BBMV from the two strains were detected. BBMV from the resistant strain had about sevenfold-lower affinity for Cry1C and threefold-higher binding site concentration than BBMV from the susceptible strain. The overall Cry1C binding affinity was just 2.5-fold higher for BBMV from the susceptible strain than it was for BBMV from the resistant strain. These results suggest that reduced binding is not the major mechanism of resistance to Cry1C.

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Section: Discussionmentioning

confidence: 88%

“…Laboratory populations of Cry1A-resistant diamondback moth can also survive on transgenic crucifers expressing a high level of Cry1Ac (17,22,38).…”

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confidence: 99%

Development and Characterization of Diamondback Moth Resistance to Transgenic Broccoli Expressing High Levels of Cry1C

Zhao

Collins

Tang

et al. 2000

Appl Environ Microbiol

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116

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“…kurstaki, Cry1Ab, Cry1Ac, and Cry1F, which is recessive in some other populations of P. xylostella (18,33,50,52), resistance to Cry1Ac in MEL showed incomplete dominance. In this respect, it was similar to resistance to Cry1Ac in the CP73-3 population of H. virescens (16), Cry1Aa in a Philippine population of P. xylostella (50) and Cry1Ca in P. xylostella (24).…”

Section: Discussionmentioning

confidence: 99%

“…If complete or partial dominance exists, at least two different gene interactions can occur (33). When the backcrossed ROTH progeny were exposed to a discriminating dose of Cry1Ac (0.04 g ml Ϫ1 ) which was eightfold greater than the LC 95 (0.005 g ml Ϫ1 ) and would kill 100% of susceptible insects, 8 families of the 12 tested had 60 to 90% mortality and 4 had 100% mortality.…”

Section: Discussionmentioning

confidence: 99%

Genetic and Biochemical Approach for Characterization of Resistance to Bacillus thuringiensis Toxin Cry1Ac in a Field Population of the Diamondback Moth, Plutella xylostella

Sayyed

Haward

Herrero

et al. 2000

Appl Environ Microbiol

143

147

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Four subpopulations of a Plutella xylostella (L.) strain from Malaysia (F 4 to F 8 ) were selected with Bacillus thuringiensis subsp. kurstaki HD-1, Bacillus thuringiensis subsp. aizawai, Cry1Ab, and Cry1Ac, respectively, while a fifth subpopulation was left as unselected (UNSEL-MEL). Bioassays at F 9 found that selection with Cry1Ac, Cry1Ab, B. thuringiensis subsp. kurstaki, and B. thuringiensis subsp. aizawai gave resistance ratios of >95, 10, 7, and 3, respectively, compared with UNSEL-MEL (>10,500, 500, >100, and 26, respectively, compared with a susceptible population, ROTH). Resistance to Cry1Ac, Cry1Ab, B. thuringiensis subsp. kurstaki, and B. thuringiensis subsp. aizawai in UNSEL-MEL declined significantly by F 9 . The Cry1Ac-selected population showed very little cross-resistance to Cry1Ab, B. thuringiensis subsp. kurstaki, and B. thuringiensis subsp. aizawai (5-, 1-, and 4-fold compared with UNSEL-MEL), whereas the Cry1Ab-, B. thuringiensis subsp. kurstaki-, and B. thuringiensis subsp. aizawai-selected populations showed high cross-resistance to Cry1Ac (60-, 100-, and 70-fold). The Cry1Ac-selected population was reselected (F 9 to F 13 ) to give a resistance ratio of >2,400 compared with UNSEL-MEL. Binding studies with 125 I-labeled Cry1Ab and Cry1Ac revealed complete lack of binding to brush border membrane vesicles prepared from Cry1Ac-selected larvae (F 15 ). Binding was also reduced, although less drastically, in the revertant population, which indicates that a modification in the common binding site of these two toxins was involved in the resistance mechanism in the original population. Reciprocal genetic crosses between Cry1Ac-reselected and ROTH insects indicated that resistance was autosomal and showed incomplete dominance. At the highest dose of Cry1Ac tested, resistance was recessive while at the lowest dose it was almost completely dominant. The F 2 progeny from a backcross of F 1 progeny with ROTH was tested with a concentration of Cry1Ac which would kill 100% of ROTH moths. Eight of the 12 families tested had 60 to 90% mortality, which indicated that more than one allele on separate loci was responsible for resistance to Cry1Ac.

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“…All primary transformants with one gene copy, as well as their progeny, showed high resistance to feeding of diamondback moth larvae (Metz et al 1995).…”

Section: Pest Resistancementioning

confidence: 99%

Genetic transformation of Brassica

Poulsen

1996

Plant Breeding

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Tissue culture regeneration of plants from Brassica species can be achieved from various explant types. Their performance, however, varies with the genotype and age of the explant and is sensitive to medium supplements and Agrobacterium cocultivation. Most Brassica transformations were carried out using Agrobacterium and it was established that nopaline and agropine strains of .4. tumefaciens and A. rhizogenes, respectively, are the most efficient. Application of virulence gene induction is ambiguous. Binary vectors are mostly apphed in spite of indications that cointegrate vectors are more efficient. Cotransformation is successful with two different bacteria or with one bacterium carrying both plasmids, however, it has proved problematic to integrate the two transgenes into separate loci. Transformations with wild type rol genes develop hairy roots, from which transgenic plants can be regenerated. Vectorless transformation is feasible with microprojectile bombardment of microspore derived embryos being the most promising.Antibiotic markers providing resistance to kanamycin, hygromycin, and spectinomycin are applicable as selectable markers, while chloramphenicol is not suitable. Among herbicides, phosphinotricin gives good results while chlorsulfuron is unsuitable for in vitro selection. Major therapeutic antibiotics being successfully applied are carbenicillin, cefotaxime, amoxycillin, and ticarcillin. Standard methods for evaluating transgenic plants also have been applied to Brassica species. Some breeding objectives obtained through genetic transformation are presented.

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Transgenic broccoli expressing aBacillus thuringiensis insecticidal crystal protein: Implications for pest resistance management strategies

Cited by 123 publications

References 45 publications

Development and Characterization of Diamondback Moth Resistance to Transgenic Broccoli Expressing High Levels of Cry1C

Development and Characterization of Diamondback Moth Resistance to Transgenic Broccoli Expressing High Levels of Cry1C

Genetic and Biochemical Approach for Characterization of Resistance to Bacillus thuringiensis Toxin Cry1Ac in a Field Population of the Diamondback Moth, Plutella xylostella

Genetic transformation of Brassica

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