Skip to Main Content
 

Global Search Box

 
 
 
 

ETD Abstract Container

Abstract Header

Mechanisms of Resistance and Candidate Gene Analysis towards Fusarium graminearum and Phytophthora sojae in Soybean

Gedling, Cassidy Renee

Abstract Details

2018, Doctor of Philosophy, Ohio State University, Plant Pathology.
Numerous diseases affect soybean [Glycine max (L.) Merr] yields throughout the growing season in Ohio. Two soil borne pathogens Fusarium graminearum and Phytophthora sojae are known to reduce stand and yield. Currently, fungicide seed treatments are used to manage these pathogens, however, host plant resistance is often the best management strategy for field crops. Thus, the overall objective of the five chapters this dissertation was to identify mechanisms and candidate genes of resistance that are effective towards seed, seedling, and root rots caused by Fusarium graminearum and P. sojae in soybean. Quantitative disease resistance loci (QDRL) have been mapped in two separate recombinant inbred line (RIL) populations for resistance to Fusarium graminearum . In the F7:8 RIL derived from a cross Magellan X PI 567516C, one major QDRL was mapped. Fine mapping of this region identified four putative candidate genes for resistance to Fusarium graminearum . In an additional population of Wyandot x PI 567301B, a major and minor QDRL was mapped to chromosome 8 and 6, respectively. Hybrid genome assembly, fine mapping, and RNA sequencing analysis narrowed the major QDRL to 2.5 cM containing three putative candidate genes for resistance or susceptibility. To validate these candidate genes functional analysis needs to be assessed at the seed level. To achieve this we modified the Apple latent spherical virus (ASLV) which allowed for direct inoculation of VIGS-triggering ALSV agro-infiltrated Nicotiana benthamiana leaves onto soybean unifoliates. However, this method is genotype dependent; the virus is detected in numerous reproductive structures including pods, embryos, stems, leaves, and roots. The last objective of this dissertation focuses on mechanisms of partial resistance to Phytophthora sojae . This oomycete is a leading pathogen of soybean, causing root and stem rot (PRR) across the North Central Region in the U.S. Twenty phenotypic quantitative trait loci (pQTL) were previously mapped in a F9:11 Conrad x Sloan recombinant inbred line (RIL) population on chromosomes 1, 4, 9, 15, 16, 18, and 19; however, these regions encompass large portions of the genome. Thus a systems genetics approach that incorporates expression QTL (eQTL) mapping, functional genomics, and gene co-expression analysis was taken to identify molecular mechanisms contributing towards partial resistance, with the specific objective of reducing the list of candidate genes potentially underpinning pQTL. A greater number of eQTL were mapped in inoculated samples relative to mock, indicating transcriptional reprogramming due to P. sojae infection. Of the six co-expression modules identified, three were related to PRR susceptibility driven by three casual hotspots. GO enrichment of casual hotspot GM_17_D indicates that cell wall modification is a putative mechanism for P. sojae resistance. A total of four eQTL and one eQTL hotspots were found to be co-localized with pQTL and identified five candidate genes for resistance.
Anne Dorrance, Dr. (Advisor)
Leah McHale, Dr. (Committee Member)
Christopher Taylor, Dr. (Committee Member)
Feng Qu, Dr. (Committee Member)
465 p.

Recommended Citations

Citations

  • Gedling, C. R. (2018). Mechanisms of Resistance and Candidate Gene Analysis towards Fusarium graminearum and Phytophthora sojae in Soybean [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1524160566193078

    APA Style (7th edition)

  • Gedling, Cassidy. Mechanisms of Resistance and Candidate Gene Analysis towards Fusarium graminearum and Phytophthora sojae in Soybean . 2018. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1524160566193078.

    MLA Style (8th edition)

  • Gedling, Cassidy. "Mechanisms of Resistance and Candidate Gene Analysis towards Fusarium graminearum and Phytophthora sojae in Soybean ." Doctoral dissertation, Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1524160566193078

    Chicago Manual of Style (17th edition)