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Screening for Resistance to Phytophthora Root Rot in Lupin

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2016, Master of Science (MS), Bowling Green State University, Biological Sciences.
Phytophthora sojae is a destructive pathogen belonging to the class Oomycota. It has a very narrow host range and infects only soybean and lupin. Infection by P. sojae overcomes most soybean resistance genes. Therefore, lupins can be perceived as a potential reservoir of novel resistance genes that can be engineered into soybean lines. Oomycetes produce motile zoospores that swim towards plant roots and subsequently cause root-rot diseases. This study focuses on determining the chemotactic behaviors of zoospores and pathogenicity of P. sojae race 2 (P6497) towards roots of ten annual lupin (Lupinus spp.) lines and a perennial line (L. perennis). The latter was further divided into three subgroups based on the degree of speckling on the seed coat; darkly speckled, lightly speckled and seeds with no speckles. Root chemotaxis assay showed no statistically significant differences between all the lupin lines tested. For pathogenicity assay, I measured disease incidence and disease severity. Interestingly, two annual lupin lines exhibited resistance to the infection of P. sojae. There was no correlation between chemotaxis of zoospores and disease severity of P. sojae on lupin. This suggests that the attack of zoospores on its host roots does not necessarily lead to root rot symptoms as there is a risk for the pathogen to be recognized by the host receptors which restrict the pathogenic invasion. When chemotactic behaviors of zoospores were tested against the metabolites extracted from lupin seeds exhibiting different seed coat phenotypes, the zoospore attachment was significantly higher towards the metabolites extracted from seed coats of all three seed phenotypes compared to the control with a preferential response to the seed coat extract of dark seeds. It is evident that zoospore attractants possibly isoflavones, are present at higher amount in darkly speckled lupin seeds compared to seeds with no speckles.
Vipaporn Phuntumart, Dr. (Advisor)
Paul Morris, Dr. (Committee Member)
Helen Michaels, Dr. (Committee Member)
82 p.

Recommended Citations

Citations

  • Beligala, G. (2016). Screening for Resistance to Phytophthora Root Rot in Lupin [Master's thesis, Bowling Green State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1467244910

    APA Style (7th edition)

  • Beligala, Gayathri. Screening for Resistance to Phytophthora Root Rot in Lupin. 2016. Bowling Green State University, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1467244910.

    MLA Style (8th edition)

  • Beligala, Gayathri. "Screening for Resistance to Phytophthora Root Rot in Lupin." Master's thesis, Bowling Green State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1467244910

    Chicago Manual of Style (17th edition)