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Development and Testing of Harpin Based Products for the Control of Nematodes and Fungal Plant Pathogens

Navarro-Acevedo, Krystel A
http://rave.ohiolink.edu/etdc/view?acc_num=osu1480631423709319

Abstract Details

2016, Master of Science, Ohio State University, Plant Pathology.
Soybean is an important crop, produced in the United States (US), with 108 M tons harvested in 2014. Soybean is affected by the plant-parasitic nematode Heterodera glycines (Ichinohe), also known as the Soybean Cyst Nematode (SCN). SCN is among the most devastating, yield limiting diseases of soybean in the US. Management of SCN has relied on the use of resistant cultivars, but overuse of the same germplasm has led to the development of virulent populations that are now capable of reproducing at high levels on resistant cultivars. Additionally, in 2007, Fusarium graminearum was first reported as a pathogen of soybean in Ohio, causing seed and root rot, and pre- and post-emergence damping-off. F. graminearum can be effectively control with fungicide seed treatments. However, the number of effective products is limited and isolates with resistance to one of the most effective active ingredients have been identified. Harpin proteins, produced by Gram-negative bacteria, are able to elicit plant defenses and induce hypersensitive cell death in non-host plants. Upon Harpin application, resistance to various bacterial and fungal pathogens had been reported. Foliar application has also shown enhanced growth and drought tolerance in Arabidopsis plants that were grown under water deficit conditions. Overall, Harpin has been described as a plant defense elicitor that can be used for the control of plant pathogens. However, development of Harpin based products has encountered many obstacles including product stability and solubility, application methodology and host-dependent interactions. Thus, the objectives of this study were to develop an efficient and effective bioassay to screen Harpin proteins for the control of SCN and F. graminearum in soybean. Foliar application of Harpin was used to assess effectiveness of Harpin towards SCN, while Harpin seed treatment was used for both SCN and F. graminearum. In Arabidopsis, foliar application was effective in reducing root-knot nematode (Meloidogyne incognita) and beet cyst nematode (Heterodera schachtii) development, but was not effective when applied to the above ground tissue of the plant. Also treatment that showed to effectively reduce the number of SCN cyst in soybean foliar application did not show to have the same effects towards other plant parasitic nematodes. This suggests that Harpin treatments are tissue and host specific and that application methods should be evaluated before screening Harpin for SCN control. The use of root exudates from Harpin treated soybean plants as an SCN egg hatching inhibitor was also evaluated and shown to be the most rapid and cost effective assay for testing and evaluating Harpin activity. SCN eggs exposed to root exudates from Harpin treated seed had reduced hatching rates as compared to the root exudates of the non-treated control. Results were then confirmed in greenhouse settings where reduced number of SCN cyst were observed for the same treatments that were effective in the root exudate assay. In a second study, the effects of temperature and base product formulation on the activity of Harpin seed treatment towards F. graminearum was evaluated. Temperature was shown to be an important factor in influencing the effectiveness of Harpin, where lesions caused by the fungus were reduced in specific Harpin treatments at 30 °C compared to 15, 20 and 25 ºC. Moreover, when maltodextrin was used as the base formulation an enhancement in disease severity was observed when compared to non-treated seeds. The starchy compound maltodextrin was shown to enhance disease severity of index caused by F. graminearum in highly resistant soybean lines. Thus, base formulation and temperatures should be examined prior to conducting Harpin studies in order to elucidate the best method for testing Harpin proteins.
Christopher G. Taylor (Advisor)
Anne E. Dorrance (Committee Member)
Jason Slot (Committee Member)
Michelle Jones (Committee Member)
94 p.
Plant Pathology

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Citations

  • Navarro-Acevedo, K. A. (2016). Development and Testing of Harpin Based Products for the Control of Nematodes and Fungal Plant Pathogens [Master's thesis, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1480631423709319

    APA Style (7th edition)

  • Navarro-Acevedo, Krystel. Development and Testing of Harpin Based Products for the Control of Nematodes and Fungal Plant Pathogens . 2016. Ohio State University, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1480631423709319.

    MLA Style (8th edition)

  • Navarro-Acevedo, Krystel. "Development and Testing of Harpin Based Products for the Control of Nematodes and Fungal Plant Pathogens ." Master's thesis, Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1480631423709319

    Chicago Manual of Style (17th edition)

osu1480631423709319
872
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