Amylase-associated genetic pattern in Xanthomonas euvesicatoria on pepper
Aastha Subedi1, Fernanda Iruegas-Bocardo1, Laixin Luo2
1Department of Plant Pathology, University of Florida, Gainesville, Florida, USA.
Applied and Environmental Microbiology
|September 18, 2024
Summary
Genomic analysis of Xanthomonas euvesicatoria reveals two distinct lineages, one with amylolytic activity emerging around 1972. Variations in type III effectors, including avrBs2 mutations, impact pepper resistance and disease management strategies.
Area of Science:
- Plant Pathology
- Microbial Genomics
- Bacteriology
Background:
- Bacterial leaf spot of pepper (BSP), caused by Xanthomonas euvesicatoria (Xe), significantly impacts global pepper production.
- Limited genomic data has hindered a comprehensive understanding of Xe population structure and genetic diversity.
- Understanding pathogen diversity is crucial for developing effective disease management strategies.
Purpose of the Study:
- To characterize the genomic and type III effector (T3E) variation within a population of Xe strains from southwest Florida.
- To investigate the population structure and evolutionary history of Xe.
- To identify genetic factors contributing to Xe virulence and host interactions.
Main Methods:
- Whole-genome sequencing of 103 Xe strains isolated from pepper in Florida, supplemented with global strains.
- Phylogenetic analysis of core genomes to determine population structure.
- Molecular clock analysis to estimate divergence times.
- GUS assays to analyze gene expression.
- Analysis of type III effector gene variation, including avrBs2.
Main Results:
- Phylogenetic analysis identified a major distinct genetic lineage associated with amylolytic activity, present globally in Xe.
- Amylolytic Xe strains emerged around 1972, with non-amylolytic strains exhibiting mutations in the alpha-amylase gene.
- Variation was observed in 12 T3Es, including two classes of mutations in avrBs2, leading to susceptibility in Bs2-resistant pepper plants.
Conclusions:
- This study reveals previously undescribed population structure in Xanthomonas euvesicatoria.
- Understanding T3E variation, particularly in avrBs2, can inform targeted disease management strategies.
- The findings emphasize the need to forecast pathogen evolution and identify genetic factors for innovative disease control.
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