Abstract
BackgroundRhizoctonia 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.ResultsFour 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.ConclusionInoculation 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.
Highlights
Rhizoctonia solani (Kühn) is a soil-borne, necrotrophic fungus causing damping off, root rot and stem canker in many cultivated plants worldwide
The primary aim of this study was to develop a high throughput method for evaluation of oilseed rape (OSR) resistance to disease caused by R. solani anastomosis group (AG) 2-1, as a first step towards the identification of traits that could be used in future breeding programs
The choice of method should be based on the scientific aim; in the present study we aimed to identify a low cost high-throughput screening method which would enable the detection of potential resistant OSR genotypes to root diseases such as AG 2-1
Summary
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. Under favourable temperatures, ranging from 18 to 20 °C, moist soil conditions and in the presence of the host, the growing hyphae infect young OSR seedlings causing pre- and post-emergence damping-off and root rot [4,5,6]. B. napus is a widely cultivated crop for oil production for human consumption and biodiesel, as well as for animal fodder It is an amphiploid species derived from the crossing of Brassica rapa and Brassica oleracea and has undergone breeding for the optimisation of oil production and yields [9]. Many studies have attempted to identify resistant or tolerant genotypes of B. napus and related species, currently there are no known resistant OSR genotypes to AG 2-1 [3, 5]
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