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Updated: Jun 6, 2026

Assessment of DNA Contamination in RNA Samples Based on Ribosomal DNA
Published on: January 22, 2018
Variations in sequence and occurrence of SSU rDNA group I introns in Monilinia fructicola isolates
Marie-José Côté1, Mireille Prud'homme, Allison J Meldrum
1Canadian Food Inspection Agency, Ottawa Laboratory (Fallowfield), Centre for Plant Quarantine Pests, 3851 Fallowfield Road, Ottawa, Ontario, K2H 8P9 Canada.
Abstract:
A group I intron of 418 base pairs in the Monilinia fructicola ribosomal small-subunit sequence was characterized. The absence of such an intron in M. laxa and M. fructigena led to a PCR test for M. fructicola identification based on the presence of this intron. The failure to amplify a PCR fragment for some isolates of M. fructicola recently lead to speculation that the intron might not be present always in M. fructicola. In this study, we analyzed 13 isolates of M. fructicola and found that the intron was absent in four isolates and we determined from sequence analysis that there are several nucleotide variations that allow the M. fructicola ribosomal SSU intron to be grouped into 6 polymorphic types.
Insights
The Monilinia fructicola ribosomal small-subunit intron is not always present and shows 6 polymorphic types. This finding impacts the reliability of PCR tests for identifying Monilinia fructicola.
Area of Science:
- Mycology
- Molecular Biology
- Plant Pathology
Background:
- A specific intron in the Monilinia fructicola ribosomal small-subunit gene was previously used for PCR-based identification.
- Recent observations indicated that this intron may not be consistently present in all M. fructicola isolates, questioning the test's reliability.
Purpose of the Study:
- To investigate the presence and variability of the ribosomal small-subunit intron in Monilinia fructicola.
- To understand the genetic basis for the observed inconsistencies in PCR-based identification.
Main Methods:
- Characterization of a group I intron within the Monilinia fructicola ribosomal small-subunit sequence.
- Analysis of 13 Monilinia fructicola isolates using PCR and DNA sequencing.
- Sequence analysis to identify nucleotide variations within the intron.
Main Results:
- The ribosomal small-subunit intron was absent in 4 out of 13 analyzed M. fructicola isolates.
- Sequence analysis revealed nucleotide variations leading to the classification of the M. fructicola ribosomal SSU intron into 6 polymorphic types.
- The presence and characteristics of the intron varied among isolates, explaining PCR test failures.
Conclusions:
- The ribosomal small-subunit intron is not universally present in Monilinia fructicola.
- Genetic polymorphism within the intron necessitates re-evaluation of PCR-based identification strategies for M. fructicola.
- Understanding intron variability is crucial for accurate fungal species identification in plant pathology.
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