Development of high-throughput methods to screen disease caused by Rhizoctonia solani AG 2-1 in oilseed rape.

Abstract

Background Rhizoctonia solani (Kühn) is a soil-borne, necrotrophic fungus causing damping off, root rot and stem canker in many cultivated plants worldwide. Oilseed rape (OSR, Brassica napus ) is the primary host for anastomosis group (AG) 2-1 of R. solani causing pre- and post-emergence damping-off resulting in death of seedlings and impaired crop establishment. Presently, there are no known resistant OSR genotypes and the main methods for disease control are fungicide seed treatments and cultural practices. The identification of sources of resistance for crop breeding is essential for sustainable management of the disease. However, a high-throughput, reliable screening method for resistance traits is required. The aim of this work was to develop a low cost, rapid screening method for disease phenotyping and identification of resistance traits. Results Four growth systems were developed and tested: (1) nutrient media plates, (2) compost trays, (3) light expanded clay aggregate (LECA) trays, and (4) a hydroponic pouch and wick system. Seedlings were inoculated with virulent AG 2-1 to cause damping-off disease and grown for a period of 4-10 days. Visual disease assessments were carried out or disease was estimated through image analysis using ImageJ. Conclusion Inoculation of LECA was the most suitable method for phenotyping disease caused by R. solani AG 2-1 as it enabled the detection of differences in disease severity among OSR genotypes within a short time period whilst allowing measurements to be conducted on whole plants. This system is expected to facilitate identification of resistant germplasm.

Plant phenotyping relevance

OSRの病害抵抗性を評価するための高スループットな病害フェノタイピング法を開発・比較検証しており、画像解析を含む表現型取得が研究の中心である。

Code and data availability

The article describes phenotyping methods (LECA trays, ImageJ analysis) but contains no public dataset, image, code, or model deposit. The authors state all data are within the article itself, and no repository or availability URL is given. The only URLs present are the license, ORCID, and funder DOI, none of which are

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