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ARS Home » Midwest Area » St. Paul, Minnesota » Plant Science Research » Research » Publications at this Location » Publication #403634

Research Project: Genetic Improvement and Cropping Systems of Alfalfa for Livestock Utilization, Environmental Protection and Soil Health

Location: Plant Science Research

Title: Disease scale development for evaluation of cultivated wild rice genotypes

item CASTELL-MILLER, CLAUDIA - University Of Minnesota
item Samac, Deborah - Debby
item KIMBALL, JENNIFER - University Of Minnesota

Submitted to: American Phytopathological Society
Publication Type: Abstract Only
Publication Acceptance Date: 8/12/2023
Publication Date: 8/16/2023
Citation: Castell-Miller, C.V., Samac, D.A., Kimball, J. 2023. Disease scale development for evaluation of cultivated wild rice genotypes. Plant Health 2023. August 12-16, 2023. Denver, Colorado.

Interpretive Summary:

Technical Abstract: Minnesota is the world’s largest producer of cultivated wild rice (CWR) where the crop has been commercially grown for over 60 years. However, grain production is often compromised by significant disease pressure caused by fungal pathogens, mainly Bipolaris spp. To accelerate the process of phenotypic selection for plant resistance, we are developing disease-specific standard area diagrams (SAD) and field diseases scales. Within SAD, we targeted leading diseases causing yield losses, such as fungal brown spot (FBS), caused by B. oryzae. Preliminary results in CWR indicate that plant defenses change over time with variability in disease symptoms occurring during the plant’s life cycle. Therefore, the SADs are being developed considering disease progression across plant development to capture that variability. Two germplasms differing in responses to B. oryzae were inoculated with the pathogen at the pre-booting and booting stage. The percentage of disease severity (%DS; percent infected leaf area) in the upper leaves increased from week 1 (pre- booting to booting) to week 6 (end of flowering). Disease progressed faster in the most susceptible genotype up to week 4, to equal the %DS of the line with greater resistance at week 6. The AUDPS were not significantly different (Prob > '2 = 0.463) between the germplasms. These results suggest differing temporal defenses associated with plant phenology and likely in response to fungal effector deployment. The FBS SAD scales will allow prompt identification of genotypes with increased resistance for genotyping and selection.