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Australian endemic pest tephritids: genetic, molecular and microbial tools for improved Sterile Insect Technique.

Raphael KA, Shearman DC, Gilchrist AS, Sved JA, Morrow JL, Sherwin WB, Riegler M, Frommer M - BMC Genet. (2014)

Bottom Line: Transcriptomes from various species, tissues and developmental stages, to aid in identification of manipulation targets for improving SIT, have been assembled and are in the pipeline.Broad analyses of the microbiome have revealed a metagenome that is highly variable within and across species and defined by the environment.More specific analyses detected Wolbachia at low prevalence in the tropics but absent in temperate regions, suggesting a possible role for this endosymbiont in future control strategies.

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ABSTRACT
Among Australian endemic tephritid fruit flies, the sibling species Bactrocera tryoni and Bactrocera neohumeralis have been serious horticultural pests since the introduction of horticulture in the nineteenth century. More recently, Bactrocera jarvisi has also been declared a pest in northern Australia. After several decades of genetic research there is now a range of classical and molecular genetic tools that can be used to develop improved Sterile Insect Technique (SIT) strains for control of these pests. Four-way crossing strategies have the potential to overcome the problem of inbreeding in mass-reared strains of B. tryoni. The ability to produce hybrids between B. tryoni and the other two species in the laboratory has proved useful for the development of genetically marked strains. The identification of Y-chromosome markers in B. jarvisi means that male and female embryos can be distinguished in any strain that carries a B. jarvisi Y chromosome. This has enabled the study of homologues of the sex-determination genes during development of B jarvisi and B. tryoni, which is necessary for the generation of genetic-sexing strains. Germ-line transformation has been established and a draft genome sequence for B. tryoni released. Transcriptomes from various species, tissues and developmental stages, to aid in identification of manipulation targets for improving SIT, have been assembled and are in the pipeline. Broad analyses of the microbiome have revealed a metagenome that is highly variable within and across species and defined by the environment. More specific analyses detected Wolbachia at low prevalence in the tropics but absent in temperate regions, suggesting a possible role for this endosymbiont in future control strategies.

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Mating scheme for the transfer of B. jarvisi markers into a B. tryoni background. (a) Mating scheme for transfer of B. jarvisi (white) mitochondria into B. tryoni (black) background. The mitochondrial type is indicated by small circle (white - B. jarvisi origin; black - B. tryoni origin). (b) Mating scheme for transfer of B. jarvisi (white) Y chromosome into B. tryoni (black) background. P, parents; F1, first filial generation; B1, backcross generation and number; and BF7, intercross of offspring from backcross generation 6. The proportion of the parental genomic contribution in the hybrids is indicated by the size of the corresponding black and white segments.
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Figure 4: Mating scheme for the transfer of B. jarvisi markers into a B. tryoni background. (a) Mating scheme for transfer of B. jarvisi (white) mitochondria into B. tryoni (black) background. The mitochondrial type is indicated by small circle (white - B. jarvisi origin; black - B. tryoni origin). (b) Mating scheme for transfer of B. jarvisi (white) Y chromosome into B. tryoni (black) background. P, parents; F1, first filial generation; B1, backcross generation and number; and BF7, intercross of offspring from backcross generation 6. The proportion of the parental genomic contribution in the hybrids is indicated by the size of the corresponding black and white segments.

Mentions: Crossing female B. jarvisi with male B. tryoni, then backcrossing the F1 and subsequent generations with male B. tryoni produces a strain of Qfly incorporating B. jarvisi mitochondria (Figure 4a) [32]. A simple PCR-based test is available to distinguish the mitochondria of the two species, thereby providing a protocol for distinguishing released flies from wild flies. The mitochondrially-marked B. tryoni stock is robust and fecund, and has been maintained in laboratory cages for 25 generations without evidence of instability. The mitochondrial marker can be incorporated into any desired Qfly strain, including the 4-way hybrids described above (Figure 2), provided that all of the females of one female parental strain in the first generation is carrying the B. jarvisi mitochondrion. There is a possibility that stains introgressed in this way may show some incompatibilities with the target species due to the presence of donor mitochondria, and therefore their utility requires testing under factory and field conditions.


Australian endemic pest tephritids: genetic, molecular and microbial tools for improved Sterile Insect Technique.

Raphael KA, Shearman DC, Gilchrist AS, Sved JA, Morrow JL, Sherwin WB, Riegler M, Frommer M - BMC Genet. (2014)

Mating scheme for the transfer of B. jarvisi markers into a B. tryoni background. (a) Mating scheme for transfer of B. jarvisi (white) mitochondria into B. tryoni (black) background. The mitochondrial type is indicated by small circle (white - B. jarvisi origin; black - B. tryoni origin). (b) Mating scheme for transfer of B. jarvisi (white) Y chromosome into B. tryoni (black) background. P, parents; F1, first filial generation; B1, backcross generation and number; and BF7, intercross of offspring from backcross generation 6. The proportion of the parental genomic contribution in the hybrids is indicated by the size of the corresponding black and white segments.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4255846&req=5

Figure 4: Mating scheme for the transfer of B. jarvisi markers into a B. tryoni background. (a) Mating scheme for transfer of B. jarvisi (white) mitochondria into B. tryoni (black) background. The mitochondrial type is indicated by small circle (white - B. jarvisi origin; black - B. tryoni origin). (b) Mating scheme for transfer of B. jarvisi (white) Y chromosome into B. tryoni (black) background. P, parents; F1, first filial generation; B1, backcross generation and number; and BF7, intercross of offspring from backcross generation 6. The proportion of the parental genomic contribution in the hybrids is indicated by the size of the corresponding black and white segments.
Mentions: Crossing female B. jarvisi with male B. tryoni, then backcrossing the F1 and subsequent generations with male B. tryoni produces a strain of Qfly incorporating B. jarvisi mitochondria (Figure 4a) [32]. A simple PCR-based test is available to distinguish the mitochondria of the two species, thereby providing a protocol for distinguishing released flies from wild flies. The mitochondrially-marked B. tryoni stock is robust and fecund, and has been maintained in laboratory cages for 25 generations without evidence of instability. The mitochondrial marker can be incorporated into any desired Qfly strain, including the 4-way hybrids described above (Figure 2), provided that all of the females of one female parental strain in the first generation is carrying the B. jarvisi mitochondrion. There is a possibility that stains introgressed in this way may show some incompatibilities with the target species due to the presence of donor mitochondria, and therefore their utility requires testing under factory and field conditions.

Bottom Line: Transcriptomes from various species, tissues and developmental stages, to aid in identification of manipulation targets for improving SIT, have been assembled and are in the pipeline.Broad analyses of the microbiome have revealed a metagenome that is highly variable within and across species and defined by the environment.More specific analyses detected Wolbachia at low prevalence in the tropics but absent in temperate regions, suggesting a possible role for this endosymbiont in future control strategies.

View Article: PubMed Central - HTML - PubMed

ABSTRACT
Among Australian endemic tephritid fruit flies, the sibling species Bactrocera tryoni and Bactrocera neohumeralis have been serious horticultural pests since the introduction of horticulture in the nineteenth century. More recently, Bactrocera jarvisi has also been declared a pest in northern Australia. After several decades of genetic research there is now a range of classical and molecular genetic tools that can be used to develop improved Sterile Insect Technique (SIT) strains for control of these pests. Four-way crossing strategies have the potential to overcome the problem of inbreeding in mass-reared strains of B. tryoni. The ability to produce hybrids between B. tryoni and the other two species in the laboratory has proved useful for the development of genetically marked strains. The identification of Y-chromosome markers in B. jarvisi means that male and female embryos can be distinguished in any strain that carries a B. jarvisi Y chromosome. This has enabled the study of homologues of the sex-determination genes during development of B jarvisi and B. tryoni, which is necessary for the generation of genetic-sexing strains. Germ-line transformation has been established and a draft genome sequence for B. tryoni released. Transcriptomes from various species, tissues and developmental stages, to aid in identification of manipulation targets for improving SIT, have been assembled and are in the pipeline. Broad analyses of the microbiome have revealed a metagenome that is highly variable within and across species and defined by the environment. More specific analyses detected Wolbachia at low prevalence in the tropics but absent in temperate regions, suggesting a possible role for this endosymbiont in future control strategies.

Show MeSH
Related in: MedlinePlus