|KANG, JIN - Michigan State University|
|HOWE, GREGG - Michigan State University|
Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: 5/27/2016
Publication Date: 11/30/2016
Citation: Okubara, P.A., Kang, J.H., Howe, G.A. 2016. Belowground signaling and defense in host-Pythium interactions. In:Vos, C., Kazan, K., editors. Belowground Defence Strategies in Plants. New York, NY: Springer Nature. p.171-194.
Interpretive Summary: Soilborne pathogens interact with host crops and with biocontrol organisms using a variety of communication pathways. The pathogens differ in response and sensitivity to defenses mounted by crop roots and by disease-suppressive compounds in the soil. In this book chapter, we summarize current knowledge about the chemical and molecular communication between a specific soilborne pathogen, biocontrol organisms and crop roots. New data on root defense for the protection of tomato from one of its major soilborne pathogens is presented.
Technical Abstract: Members of the genus Pythium interact with plants and microbial members of the rhizosphere using a variety of signaling mechanisms. Pythium irregulare, P. aphanidermatum and P. arrhenomanes are among the plant pathogenic species that share a common mode of infection, but vary in host range and virulence, possibly due to differences in nutrient acquisition and sensitivity to host and biocontrol interactions. Host innate immunity to Pythium is conferred by the jasmonic acid (JA) or ethylene (E) signal pathways in roots; triggers of these pathways include cell surface components, and metabolite and protein effectors. Roots also can mount chemical (metabolite-based) defenses against specific Pythium spp., and, reciprocally, Pythium can degrade defense metabolites. In contrast, P. oligandrum is a mycoparasite of other Pythium species, and also sends signals that trigger defense responses in plants. Interactions between plant pathogenic Pythium and biocontrol bacteria have revealed additional complexities of belowground signaling. In this chapter, we summarize current knowledge about soil-localized signaling between Pythium spp., plants and rhizosphere community members in agricultural production venues, with emphasis on molecular mechanisms. We also report new findings for the role of JA-mediated defense in protection of tomato from P. aphanidermatum.