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Updated: Aug 2, 2025
Isolation and Selection of Entomopathogenic Fungi from Soil Samples and Evaluation of Fungal Virulence against Insect Pests
Published on: September 28, 2021
Evaluation of pathogenicity of Botrytis species isolated from different legumes
Elīna Brauna-Morževska1, Frederick L Stoddard2, Biruta Bankina1
1Institute of Soil and Plant Sciences, Latvia University of Life Sciences and Technologies, Jelgava, Latvia.
Abstract:
Fungi of genus Botrytis are important pathogens of legumes, causing gray mold and chocolate spot diseases. The use of molecular methods to identify pathogens has resulted in the discovery of several new Botrytis species and new associations of pathogens with diseases. Thus, chocolate spot of faba bean is now associated with at least four species: B. fabae, B. cinerea, B. pseudocinerea and B. fabiopsis. Species of Botrytis differ in host plant, pathogenicity, fungicide resistance and other relevant properties that affect disease control. The aim of this study was to identify the species of Botrytis isolated from different legume crops and to evaluate their in vitro pathogenicity. Between 2014 and 2019, 278 isolates of Botrytis were obtained from infected legumes in Latvia. A phylogenetic analysis was carried out by sequencing three nuclear genes, RPB2, HSP60, and G3PDH, considered to be diagnostic for species in this genus. A set of 21 representative isolates was selected for pathogenicity tests on detached leaves of faba bean, field pea, lupin and soybean using 5-mm mycelium-agar plugs. The diameter of the formed lesions under the inoculated plug was measured crosswise each day. The datasets were subjected to analysis of variance with the split-plot design of the experiment and repeated-measures model. Six species were identified: B. cinerea, B. fabae, B. pseudocinerea, B. fabiopsis, B. euroamericana and B. medusae. In addition to the expected combinations of host and pathogen, naturally occurring infections of B. fabiopsis were found on chickpea, B. euroamericana on faba bean and B. medusae in lupin seeds. Species and isolate had significant effects on pathogenicity on all crops tested. Several isolates were pathogenic on two or more host species: two of B. pseudocinerea, two of B. cinerea, two of B. fabiopsis and the one of B. medusae. One isolate of B. pseudocinerea and two of B. fabiopsis caused primary lesions on all five host species. The results show that these Botrytis species have a broad host range that should be borne in mind when planning crop sequences and rotations.
Insights
Six Botrytis species were identified in Latvian legumes, revealing a broader host range than previously known. This finding is crucial for managing legume diseases and planning crop rotations effectively.
Area of Science:
- Plant Pathology
- Mycology
- Molecular Biology
Background:
- Fungi of the genus Botrytis are significant pathogens affecting legume crops, causing diseases like gray mold and chocolate spot.
- Molecular identification has expanded the known diversity of Botrytis species and their associated plant diseases.
- Chocolate spot in faba bean is now linked to at least four species: B. fabae, B. cinerea, B. pseudocinerea, and B. fabiopsis.
Purpose of the Study:
- To identify Botrytis species isolated from various legume crops in Latvia.
- To evaluate the in vitro pathogenicity of these identified Botrytis species on different legume hosts.
Main Methods:
- Phylogenetic analysis using sequences from three nuclear genes (RPB2, HSP60, G3PDH) to identify Botrytis species.
- Pathogenicity tests on detached leaves of faba bean, field pea, lupin, and soybean using mycelium-agar plugs.
- Statistical analysis of lesion diameter data using analysis of variance with a split-plot and repeated-measures model.
Main Results:
- Six Botrytis species were identified: B. cinerea, B. fabae, B. pseudocinerea, B. fabiopsis, B. euroamericana, and B. medusae.
- New host-pathogen associations were observed, including B. fabiopsis on chickpea, B. euroamericana on faba bean, and B. medusae on lupin seeds.
- Significant variations in pathogenicity were found among species and isolates, with some isolates demonstrating pathogenicity across multiple host species.
Conclusions:
- The identified Botrytis species exhibit a broad host range, impacting disease management strategies.
- Understanding the diversity and pathogenicity of Botrytis is essential for effective control measures in legume cultivation.
- Findings necessitate consideration of host range when planning crop sequences and rotations to mitigate disease spread.
