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The Bactrocera dorsalis species complex: comparative cytogenetic analysis in support of Sterile Insect Technique applications.

Augustinos AA, Drosopoulou E, Gariou-Papalexiou A, Bourtzis K, Mavragani-Tsipidou P, Zacharopoulou A - BMC Genet. (2014)

Bottom Line: Therefore, the use of the available polytene chromosome maps for B. dorsalis s.s. as reference maps for all these five biological entities is proposed.Present data provide important insight in the genetic relationships among the different members of the B. dorsalis complex, and, along with other studies in the field, can facilitate SIT applications targeting this complex.Moreover, the availability of 'universal' reference polytene chromosome maps for members of the complex, along with the documented application of in situ hybridization, can facilitate ongoing and future genome projects in this complex.

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ABSTRACT

Background: The Bactrocera dorsalis species complex currently harbors approximately 90 different members. The species complex has undergone many revisions in the past decades, and there is still an ongoing debate about the species limits. The availability of a variety of tools and approaches, such as molecular-genomic and cytogenetic analyses, are expected to shed light on the rather complicated issues of species complexes and incipient speciation. The clarification of genetic relationships among the different members of this complex is a prerequisite for the rational application of sterile insect technique (SIT) approaches for population control.

Results: Colonies established in the Insect Pest Control Laboratory (IPCL) (Seibersdorf, Vienna), representing five of the main economic important members of the Bactrocera dorsalis complex were cytologically characterized. The taxa under study were B. dorsalis s.s., B. philippinensis, B. papayae, B. invadens and B. carambolae. Mitotic and polytene chromosome analyses did not reveal any chromosomal characteristics that could be used to distinguish between the investigated members of the B. dorsalis complex. Therefore, their polytene chromosomes can be regarded as homosequential with the reference maps of B. dorsalis s.s.. In situ hybridization of six genes further supported the proposed homosequentiallity of the chromosomes of these specific members of the complex.

Conclusions: The present analysis supports that the polytene chromosomes of the five taxa under study are homosequential. Therefore, the use of the available polytene chromosome maps for B. dorsalis s.s. as reference maps for all these five biological entities is proposed. Present data provide important insight in the genetic relationships among the different members of the B. dorsalis complex, and, along with other studies in the field, can facilitate SIT applications targeting this complex. Moreover, the availability of 'universal' reference polytene chromosome maps for members of the complex, along with the documented application of in situ hybridization, can facilitate ongoing and future genome projects in this complex.

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Comparison of the 2R chromosome arm between B. dorsalis s.s. and its hybrids with B. carambolae and B. invadens. a) chromosome arm 2R of the F1 hybrid of B. dorsalis s.s. × B. carambolae, b) reference map of chromosome arm 2R of B. dorsalis s.s. and c) chromosome arm 2R of the F1 hybrid of B. dorsalis s.s. × B. invadens. Note the banding pattern similarity. Scale bar represents 10 μm.
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Figure 5: Comparison of the 2R chromosome arm between B. dorsalis s.s. and its hybrids with B. carambolae and B. invadens. a) chromosome arm 2R of the F1 hybrid of B. dorsalis s.s. × B. carambolae, b) reference map of chromosome arm 2R of B. dorsalis s.s. and c) chromosome arm 2R of the F1 hybrid of B. dorsalis s.s. × B. invadens. Note the banding pattern similarity. Scale bar represents 10 μm.

Mentions: In order to verify the identical banding pattern of the analyzed species, cytological analysis of F1 B. dorsalis s.s. × B. invadens (bidirectional) and F1 B. dorsalis s.s. × B. carambolae hybrids (bidirectional) was performed. The analysis of chromosome preparations of the hybrids did not reveal signs of fixed chromosome differences between the parental strains, evident from the perfect synapses among the parental homologous chromosomes (Figure 4). The comparison with the reference polytene chromosome maps of B. dorsalis s.s. verified that hybrids and their parental strains are homosequential with B. dorsalis s.s. (Figure 5). In both hybrids, similar to the parental strains, the asynapsis at region 73-74, together with some other minor polymorphic asynapses were observed (Figure 2b-e). The number of minor asynaptic sites was higher in the B. dorsalis s.s. × B. carambolae F1 hybrids than the B. dorsalis s.s. × B. invadens F1 hybrids.


The Bactrocera dorsalis species complex: comparative cytogenetic analysis in support of Sterile Insect Technique applications.

Augustinos AA, Drosopoulou E, Gariou-Papalexiou A, Bourtzis K, Mavragani-Tsipidou P, Zacharopoulou A - BMC Genet. (2014)

Comparison of the 2R chromosome arm between B. dorsalis s.s. and its hybrids with B. carambolae and B. invadens. a) chromosome arm 2R of the F1 hybrid of B. dorsalis s.s. × B. carambolae, b) reference map of chromosome arm 2R of B. dorsalis s.s. and c) chromosome arm 2R of the F1 hybrid of B. dorsalis s.s. × B. invadens. Note the banding pattern similarity. Scale bar represents 10 μm.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4255788&req=5

Figure 5: Comparison of the 2R chromosome arm between B. dorsalis s.s. and its hybrids with B. carambolae and B. invadens. a) chromosome arm 2R of the F1 hybrid of B. dorsalis s.s. × B. carambolae, b) reference map of chromosome arm 2R of B. dorsalis s.s. and c) chromosome arm 2R of the F1 hybrid of B. dorsalis s.s. × B. invadens. Note the banding pattern similarity. Scale bar represents 10 μm.
Mentions: In order to verify the identical banding pattern of the analyzed species, cytological analysis of F1 B. dorsalis s.s. × B. invadens (bidirectional) and F1 B. dorsalis s.s. × B. carambolae hybrids (bidirectional) was performed. The analysis of chromosome preparations of the hybrids did not reveal signs of fixed chromosome differences between the parental strains, evident from the perfect synapses among the parental homologous chromosomes (Figure 4). The comparison with the reference polytene chromosome maps of B. dorsalis s.s. verified that hybrids and their parental strains are homosequential with B. dorsalis s.s. (Figure 5). In both hybrids, similar to the parental strains, the asynapsis at region 73-74, together with some other minor polymorphic asynapses were observed (Figure 2b-e). The number of minor asynaptic sites was higher in the B. dorsalis s.s. × B. carambolae F1 hybrids than the B. dorsalis s.s. × B. invadens F1 hybrids.

Bottom Line: Therefore, the use of the available polytene chromosome maps for B. dorsalis s.s. as reference maps for all these five biological entities is proposed.Present data provide important insight in the genetic relationships among the different members of the B. dorsalis complex, and, along with other studies in the field, can facilitate SIT applications targeting this complex.Moreover, the availability of 'universal' reference polytene chromosome maps for members of the complex, along with the documented application of in situ hybridization, can facilitate ongoing and future genome projects in this complex.

View Article: PubMed Central - HTML - PubMed

ABSTRACT

Background: The Bactrocera dorsalis species complex currently harbors approximately 90 different members. The species complex has undergone many revisions in the past decades, and there is still an ongoing debate about the species limits. The availability of a variety of tools and approaches, such as molecular-genomic and cytogenetic analyses, are expected to shed light on the rather complicated issues of species complexes and incipient speciation. The clarification of genetic relationships among the different members of this complex is a prerequisite for the rational application of sterile insect technique (SIT) approaches for population control.

Results: Colonies established in the Insect Pest Control Laboratory (IPCL) (Seibersdorf, Vienna), representing five of the main economic important members of the Bactrocera dorsalis complex were cytologically characterized. The taxa under study were B. dorsalis s.s., B. philippinensis, B. papayae, B. invadens and B. carambolae. Mitotic and polytene chromosome analyses did not reveal any chromosomal characteristics that could be used to distinguish between the investigated members of the B. dorsalis complex. Therefore, their polytene chromosomes can be regarded as homosequential with the reference maps of B. dorsalis s.s.. In situ hybridization of six genes further supported the proposed homosequentiallity of the chromosomes of these specific members of the complex.

Conclusions: The present analysis supports that the polytene chromosomes of the five taxa under study are homosequential. Therefore, the use of the available polytene chromosome maps for B. dorsalis s.s. as reference maps for all these five biological entities is proposed. Present data provide important insight in the genetic relationships among the different members of the B. dorsalis complex, and, along with other studies in the field, can facilitate SIT applications targeting this complex. Moreover, the availability of 'universal' reference polytene chromosome maps for members of the complex, along with the documented application of in situ hybridization, can facilitate ongoing and future genome projects in this complex.

Show MeSH
Related in: MedlinePlus