Related Experiment Video
Updated: Jun 19, 2025
A Contrast of Three Inoculation Techniques used to Determine the Race of Unknown Fusarium oxysporum f.sp. niveum Isolates
Published on: October 28, 2021
Pathogenicity Differentiation of Fusarium spp. Causing Fusarium Basal Rot and Wilt Disease in Allium spp
Kosei Sakane1, Takashi Ueno2, Masayoshi Shigyo2
1The United Graduate School of Agricultural Sciences, Tottori University, Tottori 680-8553, Japan.
Abstract:
Here, 12 Fusarium strains, previously described as F. oxysporum f. sp. cepae (Foc), were examined via multi-locus sequencing of calmodulin (cmdA), RNA polymerase II second largest subunit (rpb2), and translation elongation factor 1-alpha (tef1), to verify the taxonomic position of Foc in the newly established epitype of F. oxysporum. The strains in this study were divided into two clades: F. nirenbergiae and Fusarium sp. To further determine the host specifications of the strains, inoculation tests were performed on onion bulbs and Welsh onion seedlings as potential hosts. Four strains (AC145, AP117, Ru-13, and TA) isolated from diseased onions commonly possessed the secreted in xylem (SIX)-3, 5, 7, 9, 10, 12, and 14 genes and were pathogenic and highly aggressive to onion bulbs, whereas all strains except for one strain (AF97) caused significant inhibition of Welsh onion growth. The inoculation test also revealed that the strains harboring the SIX9 gene were highly aggressive to both onion and Welsh onion and the gene was expressed during infection of both onions and Welsh onions, suggesting the important role of the SIX9 gene in pathogenicity. This study provides insights into the evolutionary pathogenicity differentiation of Fusarium strains causing Fusarium basal rot and wilt diseases in Allium species.
Insights
This study reclassifies Fusarium strains, revealing two distinct clades and identifying the SIX9 gene as crucial for pathogenicity in onion and Welsh onion diseases.
Area of Science:
- Plant Pathology
- Fungal Genetics
- Molecular Phylogenetics
Background:
- Fusarium oxysporum f. sp. cepae (Foc) causes significant onion diseases.
- Accurate taxonomic classification is essential for understanding pathogen evolution and host specificity.
Purpose of the Study:
- To re-evaluate the taxonomy of Foc strains using multi-locus sequencing.
- To investigate the pathogenicity and host range of these strains on Allium species.
- To identify genetic factors contributing to virulence.
Main Methods:
- Multi-locus sequencing of cmdA, rpb2, and tef1 genes for phylogenetic analysis.
- Inoculation tests on onion bulbs and Welsh onion seedlings.
- Detection and expression analysis of secreted in xylem (SIX) genes.
Main Results:
- The 12 Foc strains were divided into two clades: Fusarium nirenbergiae and Fusarium sp.
- Four strains possessing multiple SIX genes were highly pathogenic to onion bulbs.
- The SIX9 gene was strongly associated with pathogenicity in both onion and Welsh onion.
Conclusions:
- The study clarifies the taxonomic status of Foc strains, highlighting evolutionary divergence.
- The SIX9 gene plays a critical role in the pathogenicity of Fusarium on Allium species.
- Findings contribute to understanding the development of Fusarium basal rot and wilt diseases.
