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Phylogenetic and population genetic studies on some insect and plant associated nematodes

Saeb, Amr
http://rave.ohiolink.edu/etdc/view?acc_num=osu1158348092

Abstract Details

2006, Doctor of Philosophy, Ohio State University, Plant Pathology.
In this work I used the internal transcribed spacer 1 of ribosomal DNA (ITS1) and the mitochondrial genes cytochrome oxidase subunit I (cox1) and NADH dehydrogenase subunit 4 (nd4) genes to investigate genetic diversity and phylogeny of six species of the entomopathogenic nematode Heterorhabditis. The ITS1-rDNA phylogenetic trees suggested the division of the unknown isolates into two major phylogenetic groups: the HP88 group and the Oswego group. All cox1 based phylogenetic trees agreed for the division of unknown isolates into three phylogenetic groups: KMD10 and GPS5 and the HP88 group containing the remaining 11 isolates. KMD10, GPS5 represent potentially new taxa. The cox1 analysis also suggested that HP88 is divided into two subgroups: the GPS11 group and the Oswego subgroup. Our results suggest that the HP88 group is most closely related to H. downesi K122 followed by H. marelatus Oregon, H. zealandica X1, H. megidis (UK and Jun) and H. indica EG2, respectively. Neither nd4 gene sequence- nor ND4 amino acid- based phenetic and phylogenetic trees were able to completely resolve the phylogenetic relationships among species of Heterorhabditis. We concluded that cox1 gene has a potential for molecular differentiation and diagnosis between closely related species within Heterorhabditis while nd4 is not an ideal target for reconstruction of phylogeny or molecular differentiation. We also used the major sperm protein gene (msp) to investigate genetic diversity among 13 strains of Heterorhabditis bacteriophora. Phenetic and phylogenetic analysis showed the presence of high genetic structuring within H. bacteriophora. Results suggest that all the strains currently recognized as H. bacteriophora may not belong to the same species. Finally, we investigated the phylogeny and population structure of the nematode Bursaphelenchus conicaudatus and its insect vector Psacothea hilaris from the Japanese islands. Phylogenetic and phenetic analyses indicated the existence of subspecies structure in B. conicaudatus and support the current subspecies groupings of P. hilaris subspecies with few exceptions. All fixation indices indicated the presence of high genetic differentiation among the local populations of both the nematode and its insect vector. The effective numbers of migrants showed definite but limited gene flow among insect and nematode local populations.
Parwinder Grewal (Advisor)
194 p.
Biology, Genetics
Heterorhabditis; H. bacteriophora; Bursaphelenchus conicaudatus; phylogenetics; population genetics; cox1; ITS1; nd4; msp

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Citations

  • Saeb, A. (2006). Phylogenetic and population genetic studies on some insect and plant associated nematodes [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1158348092

    APA Style (7th edition)

  • Saeb, Amr. Phylogenetic and population genetic studies on some insect and plant associated nematodes. 2006. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1158348092.

    MLA Style (8th edition)

  • Saeb, Amr. "Phylogenetic and population genetic studies on some insect and plant associated nematodes." Doctoral dissertation, Ohio State University, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=osu1158348092

    Chicago Manual of Style (17th edition)

osu1158348092
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© 2006, all rights reserved.
This open access ETD is published by The Ohio State University and OhioLINK.