Biology subjects

van Westerhoven, A. C.

Publications and source records attributed to van Westerhoven, A. C..

3 recordsLinked to original sources

bioRxiv2025

Transposon activity eliminates a crucial fungal secondary metabolite cluster while preserving pathogenicity

SummaryO_LITransposable elements can significantly influence the genome dynamics of clonal fungal plant pathogens. Tropical Race 4 (TR4) is a clonal lineage within the Fusarium oxysporum species complex that poses a substantial threat to global banana production. However, how transposable elements shape TR4s genome and adaptation remains underexplored. C_LIO_LIWe investigated the activity and impact of FoHeli1, a Helitron transposable element in the TR4 lineage, focusing on a Mozambican TR4 strain (M1) through a combination of genome analyses, metabolite profiling, and infection assays. C_LIO_LIFoHeli1 activity has been very recent within the TR4 lineage and is likely still ongoing. This has resulted in large structural variations in M1, including the loss of the conserved biosynthetic gene cluster required for the production of fusaric acid. We demonstrate that this deletion abolishes fusaric acid production and alters secondary metabolite profiles, but does not affect pathogenicity. C_LIO_LIOur results emphasize the significance of transposable elements, particularly FoHeli1, in reshaping the genetic and metabolic landscape of TR4 and challenge existing assumptions about the role of fusaric acid in pathogenicity. C_LI

microbiology↗

bioRxiv2024

Extensive intrachromosomal duplications in a virulence-associated fungal accessory chromosome

Filamentous fungi have evolved compartmentalized genomes consisting of conserved core regions and dynamic accessory regions, which aid the adaptation to changing environments including the interaction with host organisms. In the Fusarium oxysporum species complex, accessory regions play an important role during infection and it has been reported that these regions undergo extensive duplications, however, it is currently unknown how such duplications shape accessory regions. Moreover, the function of accessory regions apart from encoding virulence effectors is not completely understood. Here we determined the karyotype of F. oxysporum Tropical Race 4 (TR4), which causes the ongoing pandemic of Fusarium wilt of banana (FWB). We show that the single accessory chromosome of TR4 isolate II5 has undergone extensive intrachromosomal duplications, resulting in triplication of the chromosome size compared to other closely related TR4 strains. By obtaining mutant strains that have lost the accessory chromosome, we demonstrate that this chromosome is dispensable for vegetative growth but is required for full virulence on banana. Lastly, we found that the loss of chromosome 12 co-occurs with structural rearrangements of core chromosomes, which are generally co-linear between members of the F. oxysporum species complex. Together, our results provide new insights into the chromosome dynamics of the banana infecting TR4 lineage of the F. oxysporum species complex. SignificanceFusarium oxysporum is a major fungal plant pathogen that causes vascular wilt disease on a wide variety of agronomically important crops. A current epidemic of Fusarium wilt of banana (FWB), caused by tropical race 4 (TR4), poses a major threat to global banana production and threatens food security in tropical and subtropical regions where banana is an important staple crop. Controlling TR4 requires a better understanding of the molecular mechanisms underlying pathogenicity, including the evolution of pathogenicity-related accessory regions. Here we demonstrate that intrachromosomal duplications are a key mechanism of accessory chromosome evolution in the F. oxysporum species complex. We identified a single accessory chromosome and show that TR4 mutants that lost this accessory chromosome display significantly reduced virulence on banana plants. Our results provide insight into the evolution of accessory chromosomes in the F. oxysporum species complex, underscore their importance in pathogenicity, and provide new clues for the development of resistant banana plants.

microbiology↗

bioRxiv2023

A deep genetic analysis of banana Fusarium wilt pathogens of Cuba in a Latin American and Caribbean diversity landscape

O_LIFusarium wilt of bananas (FWB) is a devastating plant disease that causes significant economic losses in banana production worldwide and is one of the major concerns for Cuban banana cultivation. The disease is caused by members of the soil-borne Fusarium oxysporum species complex. However, the genetic diversity among Fusarium species infecting bananas in Cuba is currently unknown. C_LIO_LIWe conducted a comprehensive survey of symptomatic banana plants across all production zones of the country and assembled a collection of 170 Fusarium isolates. Using genotyping- by-sequencing and whole-genome comparisons, we investigated the genetic diversity across this suite of isolates and compared it with the genetic diversity of a global Fusarium panel. C_LIO_LITypical FWB symptoms were observed in varieties of the Bluggoe cooking banana and Pisang Awak subgroups in 14 provinces. Phylogenetic analysis revealed that F. purpurascens, F. phialophorum, and F. tardichlamydosporum cause FWB in Cuba, with the latter dominating the population. Furthermore, we identified between five and seven genetic clusters, with F. tardichlamydosporum isolates divided into at least two distinct subgroups, indicating a high genetic diversity of Fusarium spp. causing FWB in the Americas. C_LIO_LIOur study provides unprecedented insights into the population genetic structure and diversity of the FWB pathogen in Cuba and the Latin American and Caribbean regions. C_LI

microbiology↗