Organic farming increases richness of fungal taxa in the wheat phyllosphere

Karlsson, Ida; Friberg, Hanna; Kolseth, Anna-Karin; Steinberg, Christian; Persson, Paula

doi:10.1111/mec.14132

Cited by 64 publications

(50 citation statements)

References 67 publications

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“…A network analysis revealed that Z. tritici co-occurs negatively with the yeasts Dioszegia, Sporobolomyces , and Cystofilobasidiaceae . A similar analysis of data from our previous study ( Sapkota et al, 2015 ) and data from Karlsson et al (2017) showed similar negative co-occurrence patterns between Z. tritici and several yeasts, thus supporting our results. The relative abundance of Z. tritici and the yeasts was strikingly constant, particularly across the samples from the three leaf positions, but also across cultivars and between GS 69–71 and 75–78.…”

Section: Discussionsupporting

confidence: 91%

Spatiotemporal Variation and Networks in the Mycobiome of the Wheat Canopy

2017

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The phyllosphere is an important habitat for a diverse microbiome and an important entry point for many pathogens. Factors that shape the phyllosphere microbiome and also the co-existence among members and how they affect disease development are largely understudied. In this study we examined the wheat mycobiome by using metabarcoding of the fungal ITS1 region. Leaf samples were taken from four cultivars grown at two locations in Denmark. Samples were taken from the three uppermost leaves and at three growth stages to better understand spatiotemporal variation of the mycobiome. Analysis of read abundances showed that geographical location had a major effect in shaping the mycobiome in the total dataset, but also leaf position, growth stage and cultivar were important drivers of fungal communities. Cultivar was most important in explaining variation in older leaves whereas location better explained the variation in younger leaves, suggesting that communities are shaped over time by the leaf environment. Network analysis revealed negative co-existence between Zymoseptoria tritici and the yeasts Sporobolomyces, Dioszegia, and Cystofilobasidiaceae. The relative abundance of Z. tritici and the yeasts was relatively constant between individual samples, suggesting that fast growing fungi rapidly occupy empty space in the phyllosphere.

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Section: Discussionsupporting

confidence: 91%

Spatiotemporal Variation and Networks in the Mycobiome of the Wheat Canopy

2017

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“…Other studies have demonstrated that wheat spikes and grains harbour a high diversity of these ascomycetes [36,39,40]. Similar trends have been observed in wheat leaves as Zymoseptoria tritici was found to be the most abundant fungus in later stage leaves [23,41]. This suggests a general increase in abundance of opportunistic or even pathogenic fungi over time in wheat tissues.…”

Section: Discussionsupporting

confidence: 66%

Fusarium Head Blight Modifies Fungal Endophytic Communities During Infection of Wheat Spikes

et al. 2019

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Fusarium head blight (FHB) is a devastating disease of wheat heads. It is caused by several species from the genus Fusarium. Several endophytic fungi also colonize wheat spikes asymptomatically. Pathogenic and commensal fungi share and compete for the same niche and thereby influence plant performance. Understanding the natural dynamics of the fungal community and how the pre-established species react to pathogen attack can provide useful information on the disease biology and the potential use of some of these endophytic organisms in disease control strategies. Fungal community composition was assessed during anthesis as well as during FHB attack in wheat spikes during 2016 and 2017 in two locations. Community metabarcoding revealed that endophyte communities are dominated by basidiomycete yeasts before anthesis and shift towards a more opportunistic ascomycete-rich community during kernel development. These dynamics are interrupted when Fusarium spp. colonize wheat spikes. The Fusarium pathogens appear to exclude other fungi from floral tissues as they are associated with a reduction in community diversity, especially in the kernel which they colonize rapidly. Similarly, the presence of several endophytes was negatively correlated with Fusarium spp. and linked with spikes that stayed healthy despite exposure to the pathogen. These endophytes belonged to the genera Cladosporium, Itersonillia and Holtermanniella. These findings support the hypothesis that some naturally occurring endophytes could outcompete or prevent FHB and represent a source of potential biological control agents in wheat.

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“…The farmers were asked to combine several subsamples into a representative sample of the field. Earlier in the season, in July 2012, wheat leaves were collected from the same fields and a number of additional data were collected at the same time (Karlsson et al, 2017). At the start and end of the transect used for leaf sampling, two 0.25 m 2 squares were laid out and weeds and crop plants in each square were cut and the biomass was separated, dried for 24 h at 105°C and weighed to determine dry mass.…”

Section: Methodsmentioning

confidence: 99%

Agricultural factors affecting Fusarium communities in wheat kernels

Karlsson

Friberg

Kolseth

et al. 2017

International Journal of Food Microbiology

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Fusarium head blight (FHB) is a devastating disease of cereals caused by Fusarium fungi. The disease is of great economic importance especially owing to reduced grain quality due to contamination by a range of mycotoxins produced by Fusarium. Disease control and prediction is difficult because of the many Fusarium species associated with FHB. Different species may respond differently to control methods and can have both competitive and synergistic interactions. Therefore, it is important to understand how agricultural practices affect Fusarium at the community level.Lower levels of Fusarium mycotoxin contamination of organically produced cereals compared with conventionally produced have been reported, but the causes of these differences are not well understood. The aim of our study was to investigate the effect of agricultural factors on Fusarium abundance and community composition in different cropping systems. Winter wheat kernels were collected from 18 organically and conventionally cultivated fields in Sweden, paired based on their geographical distance and the wheat cultivar grown. We characterised the Fusarium community in harvested wheat kernels using 454 sequencing of translation elongation factor 1-a amplicons. In addition, we quantified Fusarium spp. using real-time PCR to reveal differences in biomass between fields.We identified 12 Fusarium operational taxonomic units (OTUs) with a median of 4.5 OTUs per field. Fusarium graminearum was the most abundant species, while F. avenaceum had the highest occurrence. The abundance of Fusarium spp. ranged two orders of magnitude between fields. Two pairs of Fusarium species co-occurred between fields: F. poae with F. tricinctum and F. culmorum with F. sporotrichoides. We could not detect any difference in Fusarium communities between the organic and conventional systems. However, agricultural intensity, measured as the number of pesticide applications and the amount of nitrogen fertiliser applied, had an impact on Fusarium communities, specifically increasing the abundance of F. tricinctum. There were geographical differences in the Fusarium community composition where F. graminearum was more abundant in the western part of Sweden. The application of amplicon sequencing provided a comprehensive view of the Fusarium community in cereals. This gives us better opportunities to understand the ecology of Fusarium spp., which is important in order to limit FHB and mycotoxin contamination in cereals.

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Organic farming increases richness of fungal taxa in the wheat phyllosphere

Cited by 64 publications

References 67 publications

Spatiotemporal Variation and Networks in the Mycobiome of the Wheat Canopy

Spatiotemporal Variation and Networks in the Mycobiome of the Wheat Canopy

Fusarium Head Blight Modifies Fungal Endophytic Communities During Infection of Wheat Spikes

Agricultural factors affecting Fusarium communities in wheat kernels

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