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1.
Snowdrop (Galanthus nivalis) lectin has previously been shown to have anti-feedant and insecticidal activity towards sap-sucking insects. However, its effectiveness against plant-parasitic mites has not been demonstrated. In this study, the commercial papaya (Carica papaya L.) cultivar Kapoho, which is highly susceptible to mites, was transformed with the snowdrop lectin (G. nivalis agglutin [GNA]) gene. Polymerase chain reaction confirmed the presence of the transgene and six independent transformed lines were selected for expression analysis. Western blot analysis showed that the lines expressed a recombinant protein with a molecular weight similar to that of the native snowdrop lectin. Leaf extracts containing the recombinant GNA protein agglutinated trypsinized rabbit erythrocytes thus, showing the GNA protein to be biologically active. ELISA and indirect measurement from the agglutination assay showed there to be variation in GNA expression among the lines produced. A laboratory bioassay using carmine spider mites (Tetranychus cinnabarinus) suggested improved pest resistance in the transgenic papaya plants. This is the first report that a transgenic plant expressing the GNA gene possesses enhanced resistance to a plant-parasitic mite.  相似文献   

2.
The adoption of pest‐resistant transgenic plants to reduce yield losses and decrease pesticide use has been successful. To achieve the goal of controlling both chewing and sucking pests in a given transgenic plant, we generated transgenic tobacco, Arabidopsis, and rice plants expressing the fusion protein, AaIT/GNA, in which an insecticidal scorpion venom neurotoxin (Androctonus australis toxin, AaIT) is fused to snowdrop lectin (Galanthus nivalis agglutinin, GNA). Compared with transgenic tobacco and Arabidopsis plants expressing AaIT or GNA, transgenic plants expressing AaIT/GNA exhibited increased resistance and toxicity to one chewing pest, the cotton bollworm, Helicoverpa armigera. Transgenic tobacco and rice plants expressing AaIT/GNA showed increased resistance and toxicity to two sucking pests, the whitefly, Bemisia tabaci, and the rice brown planthopper, Nilaparvata lugens, respectively. Moreover, in the field, transgenic rice plants expressing AaIT/GNA exhibited a significant improvement in grain yield when infested with N. lugens. This study shows that expressing the AaIT/GNA fusion protein in transgenic plants can be a useful approach for controlling pests, particularly sucking pests which are not susceptible to the toxin in Bt crops.  相似文献   

3.
Snowdrop lectin ( Galanthus nivalis agglutinin; GNA) has been shown previously to be toxic towards rice brown planthopper ( Nilaparvata lugens ; BPH) when administered in artificial diet. BPH feeds by phloem abstraction, and causes ‘hopper burn’, as well as being an important virus vector. To evaluate the potential of the gna gene to confer resistance towards BPH, transgenic rice ( Oryza sativa L.) plants were produced, containing the gna gene in constructs where its expression was driven by a phloem-specific promoter (from the rice sucrose synthase RSs1 gene) and by a constitutive promoter (from the maize ubiquitin ubi1 gene). PCR and Southern analyses on DNA from these plants confirmed their transgenic status, and that the transgenes were transmitted to progeny after self-fertilization. Western blot analyses revealed expression of GNA at levels of up to 2.0% of total protein in some of the transgenic plants. GNA expression driven by the RSs1 promoter was tissue-specific, as shown by immunohistochemical localization of the protein in the non-lignified vascular tissue of transgenic plants. Insect bioassays and feeding studies showed that GNA expressed in the transgenic rice plants decreased survival and overall fecundity (production of offspring) of the insects, retarded insect development, and had a deterrent effect on BPH feeding. gna is the first transgene to exhibit insecticidal activity towards sap-sucking insects in an important cereal crop plant.  相似文献   

4.
Plant-mediated RNAi has been developed as a powerful weapon in the fight against agricultural insect pests. The gap gene hunchback (hb) is of crucial importance in insect axial patterning and knockdown of hb is deforming and lethal to the next generation. The peach potato aphid, Myzus persicae (Sulzer), has many host plants and can be found throughout the world. To investigate the effect of plant-mediated RNAi on control of this insect, the hb gene in M. persicae was cloned, plant RNAi vector was constructed, and transgenic tobacco expressing Mphb dsRNA was developed. Transgenic tobacco had a different integration pattern of the transgene. Bioassays were performed by applying neonate aphids to homozygous transgenic plants in the T2 generation. Results revealed that continuous feeding of transgenic diet reduced Mphb mRNA level in the fed aphids and inhibited insect reproduction, indicating successful knockdown of the target gene in M. persicae by plant-mediated RNAi.  相似文献   

5.
The promoter region from the rice sucrose synthase-1 gene (RSs1)was fused with coding sequences for ß-glucuronidase(GUS) and snowdrop (Galanthus nivalis) lectin (GNA). Tobaccoplants were transformed with these chimaenc genes in order todetermine the expression pattern directed by the RSs1 promoter.Histochemical and immunochemical assays demonstrated that theexpression of both GUS and GNA was restricted to phloem tissue,and was not observed in any other tissues. This phloem-specificexpression pattern was consistent in stem, leaf and root, andin different transgenic plants. Chimaeric genes of RSs 1-GUSand RSs1 GNA were stably inherited in T1 plants. In addition,GNA was detected by immunological assay in the honeydew producedby peach potato aphids (Myzus persicae) feeding on RSs1-GNAtransgenic tobacco plants. This provided direct evidence thatGNA was not only expressed in the phloem tissue, but was alsopresent in the phloem sap of transgenic tobacco plants. TheRSs1 promoter can thus be used to direct expression of an insecticidalprotein, such as GNA, in transgenic plants to control phloemsap-feeding insect pests. Key words: Rice sucrose synthase-1 promoter, phloemspecific, transgenic plants, ß-glucuronidase, Galanthus nivalis agglutinin, gene expression  相似文献   

6.
Chang T  Chen L  Chen S  Cai H  Liu X  Xiao G  Zhu Z 《Transgenic research》2003,12(5):607-614
The effects of the hta gene encoding Helianthus tuberosus agglutinin (HTA) on an insect in the order Homoptera were investigated. Homologous cDNAs of hta-a, hta-b, hta-c and hta-d with CaMV35S as promoter were introduced into tobacco via Agrobacterium tumefaciens. Southern blot results showed that the exogenous hta gene was inserted into the genome of host plants, and northern blot analysis confirmed that hta was expressed in transgenic plants. A bioassay with peach-potato aphid (Myzus persicae) demonstrated that transgenic plants had deleterious effects on the insect. The average population of aphids fed on transgenic T0 plants during an 11-day assay decreased by 70%, compared controls. In transgenic plants of T1 generation, aphid fecundity inhibitions were 53.0%(hta-b) and 64.6% (hta-c), respectively. The development of aphids was notably retarded. We conclude that hta could be a novel and promising candidate for plant transgenic engineering against homopteran insect pests.  相似文献   

7.
We used particle bombardment to transform two elite Thai rice varieties, Khao Dawk Mali 105 (KDML105) and Supanburi 60 (SP60), with the snowdrop lectin gene gna (Galanthus nivalis agglutinin). This gene confers resistance to sap-sucking insects such as the brown planthopper (BPH; Nilaparvata lugens), which is one of the most damaging pests of rice. Traditionally, KDML105 and SP60 have been regarded as recalcitrant to transformation, and this is the first account of successful gene transfer to these varieties. By molecular analysis, we confirmed the recovery of over thirty gna-transgenic lines. GNA protein expression was characterised by western blot analysis, and we achieved expression levels of up to 0.25% total soluble protein. GNA-producing R1 transgenic plants were significantly more resistant to BPH than control plants (P<0.0001), with 37% and 42% reduction in nymphal survival for constitutive and phloem-specific expression, respectively. Transferring the gna gene to these superior rice varieties thus represents a major step forward for crop improvement in Thailand, and should help to reduce the damage caused by rice pests, and hence increase yields for this vital domestic and export market.  相似文献   

8.
  • 1 Adult female Eulophus pennicornis require a source of nutrition, provided by sources such as pollen, nectar and honeydew or by host feeding, to promote longevity and facilitate egg production. There is potential for parasitoids to be exposed directly to contaminants, including gene products in transgenic crops, through feeding on plant materials, honeydew or hosts. Among such potential contaminants are lectins such as Galanthus nivalis agglutinin (GNA) and concanavalin agglutinin (Con A).
  • 2 The effect of direct exposure to honey diets containing GNA and Con A on the longevity and fecundity of E. pennicornis was examined. These lectins have been expressed in a number of plant species for the control for various insect pests. Both GNA and Con A significantly reduced longevity and fecundity at the highest concentration used (0.5% w/v). The effect on fecundity was shown to be related to a reduction in longevity.
  • 3 Examination of the gustatory response of adult female E. pennicornis to honey diet containing 1% w/v GNA or Con A revealed no significant differences in consumption rate on first exposure. A significant reduction in the time spent feeding on diet containing 1% Con A was found on the second exposure to the diet. This could have been the result of either a conditioned aversion response or the intoxication of the insect. The effect of Con A on longevity and fecundity could have been, in part, a result of reduced food intake.
  • 4 Studies on nutrition and egg resorption demonstrated that the availability of honey solution prolongs the longevity of E. pennicornis and the lack of a source of nutrition promotes oosorption.
  • 5 A greater understanding of feeding behaviour and ovigeny is required to understand fully the potential ecological consequence of transgenic crops on parasitoid species through routes of direct exposure to transgene products.
  相似文献   

9.
The gene encoding a cowpea trypsin inhibitor (CpTI), which confers insect resistance in trangenic tobacco, was introduced into rice. Expression of the CpTi gene driven by the constitutively active promoter of the rice actin 1 gene (Act1) leads to high-level accumulation of the CpTI protein in transgenic rice plants. Protein extracts from transgenic rice plants exhibit a strong inhibitory activity against bovine trypsin, suggesting that the proteinase inhibitor produced in transgenic rice is functionally active. Small-scale field tests showed that the transgenic rice plants expressing the CpTi gene had significantly increased resistance to two species of rice stem borers, which are major rice insect pests. Our results suggest that the cowpea trypsin inhibitor may be useful for the control of rice insect pests.  相似文献   

10.
In order to enhance the resistance to pests, transgenic maize (Zea mays L.) plants from elite inbred lines containing the gene encoding snowdrop lectin (Galanthus nivalis L. agglutinin; GNA) under control of a phloem-specific promoter were generated through theAgrobacterium tumefaciens- mediated method. The toxicity of GNA-expressing plants to aphids has also been studied. The independently derived plants were subjected to molecular analyses. Polymerase chain reaction (PCR) and Southern blot analyses confirmed that thegna gene was integrated into maize genome and inherited to the following generations. The typical Mendelian patterns of inheritance occurred in most cases. The level of GNA expression at 0.13%-0.28% of total soluble protein was observed in different transgenic plants. The progeny of nine GNA-expressing independent transformants that were derived separately from the elite inbred lines DH4866, DH9942, and 8902, were selected for examination of resistance to aphids. These plants synthesized GNA at levels above 0.22% total soluble protein, and enhanced resistance to aphids was demonstrated by exposing the plants to corn leaf aphid (Rhopalosiphum maidis Fitch) under greenhouse conditions. The nymph production was significantly reduced by 46.9% on GNA-expressing plants. Field evaluation of the transgenic plants supported the results from the inoculation trial. After a series of artificial self-crosses, some homozygous transgenic maize lines expressing GNA were obtained. In the present study, we have obtained new insect-resistant maize material for further breeding work.  相似文献   

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