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Investigation of Maize Root Exudates on Heterodera glycines Populations under Direct and Indirect Exposure

Medina, Rachel Morales
http://rave.ohiolink.edu/etdc/view?acc_num=osu1482499805741097

Abstract Details

2017, Master of Science, Ohio State University, Plant Pathology.
Soybean cyst nematode (SCN; Heterodera glycines) has a significant impact on the soybean industry and is responsible for $90 million in crop loss annually. SCN has been managed predominately through the use of resistant cultivars and non-host crop rotations. Recently, SCN populations have adapted to SCN-resistant cultivars making them less effective in managing this nematode. Due to the increased virulence on SCN resistant soybean varieties, crop rotation is becoming an increasingly important part of SCN management. Previous reports suggest that SCN numbers can be reduced during rotations with maize, but the underlying mechanism of this interaction is unknown. In addition, there are reports that some SCN populations may not be declining when non-host plants are planted. This study aimed to identify if there were differences among twenty- five maize parental lines from the Nested Association Mapping (NAM) population in their ability to decrease SCN populations and determine if allelopathic chemicals in the root exudates contribute to this effect. Specifically, if benzoxazinoids, such as 2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one (DIMBOA), have a direct or indirect impact on SCN populations in infested soils through reduced hatching and reproduction. Hatching chambers were used to measure whether maize root exudates altered SCN egg hatching as compared to a water control. It was observed that of the twenty lines tested, though not significant, nine lines stimulated hatching and four lines significantly inhibited hatching while two lines showed no effects on SCN hatching. The effect of maize root exudates was also studied in both greenhouse and field experiments using an accelerated crop rotation scheme with maize and soybean to investigate the impact that root exudates could have on SCN. In greenhouse trials, soybeans following eight different maize lines were observed to have a significant reduction in SCN cyst production. Soils taken from micro- plot experiments showed that there were fewer eggs recovered from soil when soybeans followed ten different maize genotypes. To gain a better understanding of the biochemical composition of the maize lines used, LC-MS/MS analyses was conducted and DIMBOA within the root systems of hydroponically grown maize lines was quantified. The levels of DIMBOA found within the maize lines ranged widely, as expected. The amount of DIMBOA in roots was compared to the levels of hatching in the hatch chamber experiments and the changes in SCN populations when soybeans were planted after each of the maize genotypes. There was no correlation between the level of DIMBOA and the effects measures on hatching or population changes. A major finding from these studies was that the maize genotype can greatly influence the impact of SCN hatch and population numbers. This may in part explain the reduced “non-host rotation effect” that has been observed in some areas. Identifying the biochemical traits in the maize genotypes that contribute to reduction in eggs will greatly aide in screening and future development of maize hybrids to grow in SCN infested fields.
Christopher Taylor, Dr. (Advisor)
Anne Dorrance, Dr. (Committee Member)
Joshua Blakeslee, Dr. (Committee Member)
156 p.
Plant Pathology

Recommended Citations

Citations

  • Medina, R. M. (2017). Investigation of Maize Root Exudates on Heterodera glycines Populations under Direct and Indirect Exposure [Master's thesis, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1482499805741097

    APA Style (7th edition)

  • Medina, Rachel. Investigation of Maize Root Exudates on Heterodera glycines Populations under Direct and Indirect Exposure. 2017. Ohio State University, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1482499805741097.

    MLA Style (8th edition)

  • Medina, Rachel. "Investigation of Maize Root Exudates on Heterodera glycines Populations under Direct and Indirect Exposure." Master's thesis, Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1482499805741097

    Chicago Manual of Style (17th edition)

osu1482499805741097
156
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This open access ETD is published by The Ohio State University and OhioLINK.