Characteristics of<i>Rhizoctonia</i>Isolates Associated with Bottom Rot of Lettuce in Organic Soils in Ohio

Herr, L. J.

doi:10.1094/phyto-82-1046

Cited by 19 publications

(19 citation statements)

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“…Hence, the principal management method for R. solani in lettuce production is crop rotation, which in southwestern Québec mainly includes onions and carrots. Worldwide, the production areas in the United States, Brazil, and Germany also experienced outbreaks of basal rot caused by different anastomosis groups (AGs) of Rhizoctonia solani [5][6][7][8].…”

Section: Introductionmentioning

confidence: 99%

Detection and Quantification of Rhizoctonia solani and Rhizoctonia solani AG1-IB Causing the Bottom Rot of Lettuce in Tissues and Soils by Multiplex qPCR

Wallon

Sauvageau

Heyden

2020

Plants

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In the muck soil region of southwestern Quebec, vegetable growers are threatened by several soilborne diseases, particularly the bottom rot of lettuce caused by the fungus Rhizoctonia solani. The particularly warm temperature of the few last seasons was marked by an increase in disease severity, and the associated yield losses were significant for Quebec lettuce growers. In the absence of registered fungicides and resistant cultivars, the management of Rhizoctonia solani-induced diseases in lettuce is based on good agricultural practices, which require detailed knowledge of the pathogen. In this study, Rhizoctonia solani fungal strains were isolated from infected field-grown lettuce plants presenting bottom rot symptoms to determine the anastomotic groups (AGs) of these isolates by internal transcribed spacer region (ITS) sequencing. Rhizoctonia solani AG 1-IB was identified as the main anastomotic group causing bottom rot lettuce in field-grown lettuce in organic soils in the Montérégie region. Two specific and sensitive quantitative PCR assays were then developed for R. solani AG1-IB and R. solani. The AG 1-IB qPCR assay amplified all strains of R. solani AG 1-IB tested, and no PCR product was obtained for any non-target strains. The R. solani qPCR assay amplified all strains of R. solani and did not amplify non-target strains, except for two strains of binucleate Rhizoctonia AG-E. In artificially inoculated soils, the sensitivity of both qPCR assays was set to 1 μg of sclerotia g−1 of dry soil. In the growth chamber experiment, a minimum concentration between 14 and 42 μg sclerotia g−1 of dry soil was required to induce the development of symptoms on the lettuce. Indeed, the AG 1-IB qPCR assay was sensitive enough to detect the lowest soil concentration of AG1-IB capable of inducing symptoms in head lettuce. In addition, the qPCR assays successfully detected R. solani and R. solani AG 1-IB from infected plant tissue samples and soil samples from lettuce fields. The qPCR assays developed in this study will be useful tools in lettuce bottom rot management.

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Section: Introductionmentioning

confidence: 99%

Detection and Quantification of Rhizoctonia solani and Rhizoctonia solani AG1-IB Causing the Bottom Rot of Lettuce in Tissues and Soils by Multiplex qPCR

Wallon

Sauvageau

Heyden

2020

Plants

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“…This pathogen causes bottom rot disease (Wareing et al. 1986; Herr 1992; Grosch et al. 2004), and in South Germany alone, crop losses due to this disease can reach as much as 250.000 € per year (Laun 2002).…”

Section: Introductionmentioning

confidence: 99%

Impact of Continuous Cropping of Lettuce on the Disease Dynamics of Bottom Rot and Genotypic Diversity of Rhizoctonia solani AG 1-IB

Grosch

Schneider²,

Kofoet

et al. 2010

Journal of Phytopathology

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The impact of continuous cropping of lettuce on the disease dynamics of bottom rot and genotypic diversity of the causal pathogen Rhizoctonia solani AG 1-IB was studied over 3 years with two crops per year within a field naturally infested with R. solani the pathogen. This field had not had lettuce cultivated in it for 7 years. The disease incidence (DI) and disease severity (DS) were assessed at each harvest and mapped. Surprisingly, a high DI was already observed in the first crop of year one of this field study. In addition, the pathogen was also found to be evenly distributed. Severely infected plants occurred mainly in patches, and the position varied between crops. A significant increase in DS was already observed in the second year, and both temperature conditions and continuous cropping influenced the DS on average over time. Rhizoctonia isolates were randomly collected from the first crop in 1999 and the sixth crop in 2001. The genotypic diversity within the subgroup of R. solani AG 1-IB was analysed by BOX-PCR genomic fingerprinting and the aggressiveness of isolates by bioassay. The fingerprints revealed a high level of genotypic diversity within the AG 1-IB field population. However, continuous cropping was found not to have an impact on genotypic diversity and aggressiveness.

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“…However, different AGs have been isolated from bottom rot lettuce plants (Wareing et al. 1986; Herr 1992) along with Botrytis cinerea Pers that usually occurs in the bottom rot disease complex of lettuce (Reglinski et al. 1995).…”

Section: Introductionmentioning

confidence: 99%

Development of a specific PCR assay for the detection of Rhizoctonia solani AG 1-IB using SCAR primers

et al. 2007

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Aims: The aim of this study was to develop a specific and sensitive identification method for Rhizoctonia solani AG 1‐IB isolates based on phylogenetic relationships of R. solani AG‐1 subgroups using rDNA‐internal transcribed spacer (rDNA‐ITS) sequence analysis. Methods and Results: A neighbour‐joining tree analysis of 40 rDNA‐ITS sequences demonstrated that R. solani AG‐1 isolates cluster separately in six subgroups IA, IB, IC, ID, IE and IF. A molecular marker was generated from a random amplified polymorphic DNA fragment (RAPD). After conversion into a sequence‐characterized amplified region (SCAR), a specific primer set for identification of subgroup AG 1‐IB was designed for use in a polymerase chain reaction (PCR). The primer pair amplified a single DNA product of 324 bp. Conclusions: R. solani AG‐1 subgroups were discriminated by sequence analysis of the ITS region. The designed SCAR primer pair allowed an unequivocal and rapid detection of R. solani AG 1‐IB in plant and soil samples. Significance and Impact of the Study: Sequence analysis of the rDNA‐ITS region can be used for differentiation of subgroups within AG‐1. The use of the developed SCAR primer set allowed a reliable and fast identification of R. solani AG 1‐IB and provides a powerful tool for disease diagnosis.

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Characteristics ofRhizoctoniaIsolates Associated with Bottom Rot of Lettuce in Organic Soils in Ohio

Cited by 19 publications

References 0 publications

Detection and Quantification of Rhizoctonia solani and Rhizoctonia solani AG1-IB Causing the Bottom Rot of Lettuce in Tissues and Soils by Multiplex qPCR

Detection and Quantification of Rhizoctonia solani and Rhizoctonia solani AG1-IB Causing the Bottom Rot of Lettuce in Tissues and Soils by Multiplex qPCR

Impact of Continuous Cropping of Lettuce on the Disease Dynamics of Bottom Rot and Genotypic Diversity of Rhizoctonia solani AG 1-IB

Development of a specific PCR assay for the detection of Rhizoctonia solani AG 1-IB using SCAR primers

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