Culturable Fungi of Stored ‘Golden Delicious’ Apple Fruits: A One-Season Comparison Study of Organic and Integrated Production Systems in Switzerland

Abstract

The effects of organic and integrated production systems on the culturable fungal microflora of stored apple fruits from five matched pairs of certified organic and integrated 'Golden Delicious' farms were studied at five representative production sites in Switzerland. Isolated fungi were identified morphologically. Colonization frequency (percentage of apples colonized), abundance (colony numbers), and diversity (taxon richness) were assessed for each orchard. The standard quality of the stored fruits was comparable for both organic and integrated apples and complied with national food hygiene standards. Yeasts (six taxa) and the yeast-like fungus Aureobasidium pullulans were the dominant epiphytes, filamentous fungi (21 taxa) the dominant endophytes. The most common fungi occurred at all sites and belonged to the "white" and "pink" yeasts, yeast-like A. pullulans, filamentous fungi Cladosporium spp., Alternaria spp., and sterile filamentous fungi. Canonical correspondence analysis of the total fungal community revealed a clear differentiation among production systems and sites. Compared to integrated apples, organic apples had significantly higher frequencies of filamentous fungi, abundance of total fungi, and taxon diversity. The effects of the production system on the fungal microflora are most likely due to the different plant protection strategies. The incidence of potential mycotoxin producers such as Penicillium and Alternaria species was not different between production systems. We suggest that higher fungal diversity may generally be associated with organic production and may increase the level of beneficial and antagonistically acting species known for their potential to suppress apple pathogens, which may be an advantage to organic apples, e.g., in respect to natural disease control.

Fungal Endophytic Communities in Grapevines (Vitis vinifera L.) Respond to Crop Management

“…In contrast to grasses and annual plants, fewer attempts have been made in woody plants to correlate fungal endophytic communities with cultivar (17, 30). To our knowledge, only a few studies attempt to link organic management or the use of antifungal treatments with modifications in the microbiota in woody plants (31,54,60).When attempting to identify a high number of isolated fungi, as in environmental studies, isolation and purification of DNA is both time-consuming and expensive but required for the PCR amplification of taxonomically relevant DNA regions. Direct colony-PCR of fungal isolates is usually avoided since DNA availability and purity in heat-lysed fungi is frequently insufficient for the reaction (7).…”

“…In contrast to grasses and annual plants, fewer attempts have been made in woody plants to correlate fungal endophytic communities with cultivar (17, 30). To our knowledge, only a few studies attempt to link organic management or the use of antifungal treatments with modifications in the microbiota in woody plants (31,54,60).…”

Functional and Structural Microbial Diversity in Organic and Conventional Viticulture: Organic Farming Benefits Natural Biocontrol Agents

“…An alternative to conventional agriculture is offered by organic farming, which aims to minimize its impact on the environment by using crop rotation, pathogen-resistant cultivars, limited amounts of chemical pesticides, and organic manure instead of synthetic fertilizers. However, the beneficial effect of organic agriculture on biodiversity in general and plant-associated microorganisms in particular is still controversial (6,8,9,14).…”

“…Conversely, bands for A. pullulans were stronger from organic treatment samples. A. pullulans is a cosmopolitan yeastlike (black) fungus and is ubiquitously associated with plants, including grapevines (5,8). Cladosporium sp.…”

Genetically modified crops in Switzerland: implications for agrosystem sustainability evidenced by multi-criteria model

“…Horizontal gene transfer is not considered (f. ex. to bacteria) (Bartsch and Schmidt 1997;Reim et al 2006;Demont and Devos 2008;Granado et al 2008;Speiser et al 2013;Melé et al 2015) Persistence Influence of transgene (s) attribute are summarised on the model structure (Figs. 2 and 3).…”