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Genetic Engineering of Rubber Producing Dandelions

Zhang, Yingxiao
http://rave.ohiolink.edu/etdc/view?acc_num=osu1480626773100647

Abstract Details

2016, Doctor of Philosophy, Ohio State University, Horticulture and Crop Science.
Natural rubber (cis-1, 4-polyisoprene) is a biopolymer of significance used in both manufacturing and our daily lives. Unfortunately, the current rubber production system, based on the Para rubber tree (Hevea brasiliensis), is unsustainable due to increasing costs of manual latex collection, competition with other cash crops, and the pervasive threat of South American Leaf Blight, a fatal fungal pathogen. It is imperative to develop alternative rubber-producing crops. Rubber dandelion (Taraxacum kok-saghyz, TK) and Taraxacum brevicorniculatum (TB) are dandelion species which produce rubber in roots and have several desirable agronomic characteristics. TK is currently under development as an alternative rubber producing crop while TB is a model species for rubber biosynthesis. TK domestication will inevitably involve the introduction of novel traits through breeding or genetic modifications. To develop tools to monitor the potential gene flow between TK and its ubiquitous weedy relative, common dandelion (Taraxacum officinale, TO), chloroplast genomes have been sequenced for TK, TB and TO and chloroplast and nuclear species-specific markers have been developed and validated. The genomic and marker resources generated here provide a molecular tool kit for germplasm identification and gene flow studies. To advance crop improvement efforts by biotechnology, a rapid and hormone-free Agrobacterium rhizogenes-mediated transformation system was developed for TK and TB. By using root fragments as explants, non-composite transgenic plants were obtained within 8 weeks and the average transformation efficiency for TK and TB was 24.7% and 15.7%, respectively. Protocols developed here were used to transform TK and TB with rubber biosynthesis genes. The rate-limiting enzyme in the mevalonate pathway (MVA pathway), 3-hydroxy-3-methyl-glutaryl-coenzyme A reductase (HMGR), was introduced into TK and TB. Six genes encoding the entire MVA pathway were introduced into TK and the corresponding enzymes were located to chloroplast. Transgenic plants generated here will be used for metabolic analysis to understand genetic regulation of rubber biosynthesis. Due to the rapid development of novel biotechnologies, precise gene manipulation methods were also developed. A fast pipeline was developed to apply genome editing to TK using CRISPR/Cas9 (clustered regularly interspaced short palindromic repeats/CRISPR associated protein 9). In parallel, preliminary attempts were made to manipulate the plastid genome using plastid engineering. Overall, this research will facilitate biogenesis studies, as well as domestication and commercialization of rubber producing dandelions.
Katrina Cornish, Dr. (Advisor)
Joshua Blakeslee, Dr. (Advisor)
John Cardina, Dr. (Committee Member)
Feng Qu, Dr. (Committee Member)
189 p.
Bioinformatics; Biology; Cellular Biology; Ecology; Horticulture; Molecular Biology; Plant Biology; Plant Sciences
natural rubber; rubber-producing dandelions; Taraxacum kok-saghyz; Taraxacum brevicorniculatum; Taraxacum officinale; chloroplast genome; species-specific molecular markers; genetic engineering; CRISPR genome editing; plastid engineering

Recommended Citations

Citations

  • Zhang, Y. (2016). Genetic Engineering of Rubber Producing Dandelions [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1480626773100647

    APA Style (7th edition)

  • Zhang, Yingxiao. Genetic Engineering of Rubber Producing Dandelions. 2016. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1480626773100647.

    MLA Style (8th edition)

  • Zhang, Yingxiao. "Genetic Engineering of Rubber Producing Dandelions." Doctoral dissertation, Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1480626773100647

    Chicago Manual of Style (17th edition)

osu1480626773100647
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This open access ETD is published by The Ohio State University and OhioLINK.