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ARS Home » Plains Area » El Reno, Oklahoma » Oklahoma and Central Plains Agricultural Research Center » Peanut and Small Grains Research Unit » Research » Publications at this Location » Publication #366631
Research Project: Genetic Improvement of Peanut for Production in the Southwest United States Region

Location: Peanut and Small Grains Research Unit

Title: Growth chamber assay for evaluating resistance to Athelia rolfsii

Author
item Bennett, Rebecca

Submitted to: Peanut Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/16/2020
Publication Date: 7/1/2020
Citation: Bennett, R. 2020. Growth chamber assay for evaluating resistance to Athelia rolfsii. Peanut Science. (47)1:25-32. https://doi.org/10.3146/PS19-12.1.
DOI: https://doi.org/10.3146/PS19-12.1

Interpretive Summary: Planting resistant cultivars is the most sustainable strategy for managing Athelia rolfsii, one of the most damaging pathogens of peanut worldwide. However, evaluating germplasm for resistance in the field can be hindered by unfavorable environmental conditions, uneven distribution of pathogens in soil, and difficulty in growing non-standard peanut genotypes such as wild species. Thus, a growth-chamber assay was developed to screen for resistance to A. rolfsii in the laboratory. Thirteen peanut genotypes were used to test the assay, and measurements of lesion length, as well as length of visible mycelium on the main stem and side stems were recorded at 4 to 13 days after inoculation. The assay identified highly susceptible and most of the highly resistant genotypes. However, the assay was less able to discriminate among genotypes with intermediate resistances. Despite this limitation, the assay may be useful for pre-screening germplasm for highly resistant and susceptible entries, as well as screening Arachis species that are difficult to grow in the field.

Technical Abstract: Planting resistant cultivars is the most sustainable strategy for managing Athelia rolfsii, one of the most damaging pathogens of peanut worldwide. However, evaluating germplasm for resistance in the field can be complicated by unfavorable environmental conditions, uneven distribution of sclerotia in soil, and difficulty in growing non-standard peanut genotypes such as wild species. Thus, a growth-chamber assay was developed to screen for resistance to A. rolfsii in the laboratory. Thirteen peanut genotypes were used to test the assay: cultivars Georgia-03L, Georgia-12Y, Florida-07, Georgia-07W, Tamrun OL02, FloRun '107', Georgia-06G, and U.S. mini-core accessions CC038 (PI 493581), CC041 (PI 493631), CC068 (PI 493880), CC384 (PI 155107), CC650 (PI 478819), and CC787 (PI 429420). Lesion length, as well as length of visible mycelium, on the main stem and a side stem were recorded at 4, 7, 10, and 13 days after inoculation. In general, patterns of lesion and mycelium growth were similar. The most resistant genotypes, Georgia-03L and CC650, had the smallest lesions and least mycelium growth. Georgia-12Y, one of the most resistant cultivars available today, appeared less resistant than Georgia-03L in the assay. Other commercial cultivars were intermediate in lesion and mycelium lengths. The most susceptible entries were CC038, CC041, and CC787. Despite limitations in discriminating among genotypes with intermediate resistance to A. rolfsii, these assays may be useful for pre-screening germplasm to identify physiologically resistant and highly susceptible entries, well as for screening Arachis species that are difficult to grow in the field.