Nematode resistance in perennial glycine species, genetic mapping of resistance in g. Latifolia to Meloidogyne incognita, and analysis of nematode communities in Illinois

Southern root-knot nematode (Meloidogyne incognita), reniform nematode (Rotylenchulus reniformis), and lesion nematode (Pratylenchus penetrans) cause substantial yield losses to soybean (Glycine max). Deploying host resistance is considered a sustainable option to control nematodes, but soybean resistance to these nematode species may be overcome by more aggressive populations or high densities of the nematodes. Wild perennial relatives of soybean have unique genetic resources that can be used to enhance nematode resistance traits in soybean. In addition to these three species of nematodes, there are diverse plant-parasitic and free-living nematodes that are known to occur in soybean and corn fields in Illinois. Though it is important to assess the potential risk for yield losses due to these pathogens, there are no recent published surveys of plant-parasitic nematodes in Illinois. This dissertation explores the potential of wild perennial Glycine species to enhance disease resistance to the three nematode species and determine the distribution and population densities of nematode communities in organic soybean fields and non-organic corn fields in Illinois. I demonstrated the potential of perennial Glycine species to harbor resistance to Meloidogyne incognita and Rotylenchulus reniformis. Among eighteen accessions tested, three accessions of G. clandestina and G. tomentella had resistance to both nematode species. In contrast, no resistance to P. penetrans was recorded in any perennial Glycine species. To identify a genetic region controlling M. incognita resistance in perennial Glycine species, I used previously established G. latifolia recombinant inbred lines and 1,419 single nucleotide polymorphism markers. I detected a single locus on chromosome 13 significantly associated with M. incognita resistance, explaining 32.7% of phenotypic variance. Interestingly, the locus was syntenic with a locus on G. max chromosome 13, previously found associated with resistance to multiple Meloidogyne species and other non-nematode pathogens that infect soybean. From field surveys of nematodes in Illinois organic soybean fields, I found six plant-parasitic nematode taxa, including spiral (Helicotylenchus spp.), lesion (Pratylenchus spp.), cyst (Heteroderidae), stunt (Tylenchorhynchus spp.), dagger (Xiphinema spp.), and pin nematodes (Paratylenchus spp.). Among the taxa, 62%, 40%, and 25% of spiral, lesion, and dagger nematode-positive samples were above previously established damage threshold levels in some fields. Organic fields under long-term rotation with soybean supported more total nematode and cyst nematode abundances in the summer sampling season and had more structured food web in the fall sampling season compared with fields under short-term rotation with soybean. In Illinois corn fields, I found a total of 10 plant-parasitic nematode taxa: spiral, lesion, cyst, stunt, lance (Hoplolaimus spp.), dagger, pin, needle (Longidorus spp.), stubby-root (Trichodoridae), and ring nematodes (Criconematidae). Among the 10 nematode taxa, 7.1%, 4.1%, and 2.3% of lesion, spiral, and lance nematode-positive samples exceeded estimated damage thresholds in some fields. Overall, this dissertation identified novel nematode resistance sources from perennial Glycine species and a locus associated with M. incognita resistance in G. latifolia, and report diversity and populations of plant-parasitic and free-living nematodes in Illinois organic soybean and non-organic corn production fields.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Crop Sciences

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2022

Author dc:creator

• Han, Jaeyeong

Contributors dc:contributor

• Hartman, Glen L
• Schroeder, Nathan E
• Domier, Leslie L
• Ugarte, Carmen M
• Lambert, Kris N

• nematode
• root-knot nematode
• soybean
• perennial Glycine

Statement dc:rights

• Copyright 2022 Jaeyeong Han

Language dc:language

en, eng

Handle dc:identifier

https://hdl.handle.net/2142/115580

OAI record oai:identifier

https://www.ideals.illinois.edu/oai-pmh?verb=GetRecord&metadataPrefix=etdms&identifier=oai%3Awww.ideals.illinois.edu%3A2142%2F115580