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ARS Home » Pacific West Area » Corvallis, Oregon » Forage Seed and Cereal Research Unit » Research » Publications at this Location » Publication #381857
Research Project: Development of Genetic, Genomic and Molecular Resources to Improve Performance, Adaptability and Utility of Cool Season Grasses and Cover Crops

Location: Forage Seed and Cereal Research Unit

Title: Choke expression in Epichloë typhina seedling-infected orchardgrass (Dactylis glomerata) germplasm

Author
item MERLET, LEA - Oregon State University
item Bushman, Shaun
item Dombrowski, James
item Martin, Ruth

Submitted to: Seed Production Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/2/2021
Publication Date: 4/1/2021
Citation: Merlet, L., Bushman, B.S., Dombrowski, J.E., Martin, R.C. 2021. Choke expression in Epichloë typhina seedling-infected orchardgrass (Dactylis glomerata) germplasm. Seed Production Research. 164:40-47.

Interpretive Summary: Choke disease was first discovered in orchardgrass seed production fields in the Willamette Valley of Oregon in 1997 and is now prevalent in orchardgrass seed production fields in the Willamette Valley Oregon, where it is estimated to cause up to 30% losses in seed yield. Multiple efforts at controlling this disease through various management practices have been unsuccessful. With the high incidence of choke and lack of control options, development of choke resistant germplasm was initiated previously as a potential long-term approach for disease management. The objective of this research is to evaluate the progeny from parents previously identified as being less susceptible to choke. As part of this study, very young seedlings were inoculated with the pathogen (Epichloë typhina) that causes choke disease. The ability to infect progeny varied greatly between accessions. We also found large variations in the ability of pre-inoculated plants from different accessions to produce normal flowers under field conditions. These pre-inoculated seedlings will be valuable for characterizing orchardgrass germplasm for their ability to flower even when infected with Epichloë typhina and will complement traditional disease resistance screening studies.

Technical Abstract: Choke disease, which is caused by Epichloë typhina, is widespread in orchardgrass seed production fields in the Willamette Valley, where it can cause up to 30% losses in seed yields. Multiple efforts at controlling this disease through insect control, fungicides, fertility management, cutting/burning stubble, and using plant growth regulators have been unsuccessful. With the high incidence of choke and lack of control options, development of choke resistant germplasm was initiated previously as a potential long-term approach for disease management. The objective of this research is to evaluate the progeny from parents previously identified as being less susceptible to choke. As part of this study, very young seedlings were inoculated with the pathogen (Epichloë typhina) that causes choke. The ability to infect progeny varied greatly between accessions. We also found large variation in the ability of these pre-inoculated plants from different accessions to produce normal flowers under field conditions. These pre-inoculated seedlings will be valuable for characterizing orchardgrass germplasm for their ability to flower even when infected with Epichloë typhina and will complement traditional disease resistance screening studies. Companion plots with non-inoculated plants were also included in this study, but very little choke disease was evident in those plots.