Olive Fungal Epiphytic Communities Are Affected by Their Maturation Stage.

Joana Castro,Paula Baptista,Teresa Lino-Neto,Rui M Tavares,Daniela Costa

doi:10.3390/microorganisms10020376

Joana Castro, Paula Baptista + Show 3 more

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https://doi.org/10.3390/microorganisms10020376

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Abstract

The phyllosphere comprises the aerial parts of plants and is colonized by a great diversity of microorganisms, either growing inside (as endophytes) or on the surface (as epiphytes) of plant tissues. The factors that structure the diversity of epiphytes and the importance of these microorganisms for host plant protection have been less studied when compared to the case of endophytes. In this work, the epiphytic fungal communities from fruits of the olive tree (olives) in different maturation stages (green and semi-ripened), obtained from different olive orchard managements (integrated and organic production) and from distinct cultivars displaying different susceptibilities to olive anthracnose (Cobrançosa and Madural), are compared by using a metabarcoding approach. We discuss whether such differences in host resistance against anthracnose depend on both the fungal taxa or fungal community composition. A total of 1565 amplicon sequence variants (ASVs) were obtained, mainly belonging to the Ascomycota phylum and Saccharomycetes class. Although significant differences on epiphytic fungal richness were observed among olives obtained in different production systems and maturation stages, these factors in addition to host cultivar did not influence the composition of the epiphytes. Despite these results, a co-inertia analysis showed that Aureobasidium spp. and Sporocadaceae spp. were positively associated with the green olives of the cv. Madural produced under integrated production, while Saccharomycetales spp. (Kluyveromyces, Candida, Kazachstania and Saccharomyces) were positively associated with the semi-ripened olives of the cv. Cobrançosa obtained from organic production. The discriminant power of these fungi, some of them recognized as biocontrol agents, suggest that they might be important in conferring differences on host plant susceptibility to anthracnose.

Highlights

The olive tree (Olea europaea L.) is cultivated in distinct world geographical regions for the production of olives for table consumption and oil production
Almost 43% of total processed reads were classified as fungal taxa (1565 amplicon sequence variants (ASVs)), the remaining being identified as plant sequences (1033 ASVs) or unclassified taxa (458 ASVs)
These results suggest that a beneficial fungal community results suggest thatnose, a beneficial fungal community is developed under the studied production systems. is developed under the studied production systems

Summary

Introduction

The olive tree (Olea europaea L.) is cultivated in distinct world geographical regions for the production of olives for table consumption and oil production. The traditional olive production has been replaced by intensive and super-intensive cultivation systems [2], due to the increasing international demand for olive oil and table olives [1]. These production systems are not compatible with sustainable agriculture (organic and integrated productions), which are the pillars of the European Model for Agriculture, according to the Directive 2009/128/EC. Both organic and integrated productions system are, in general, associated with the presence of high biodiversity, and provide several important ecosystem services when compared to the intensive and super-intensive olive. A diverse microbial community has been recognized to inhabit the aerial parts of plants (phyllosphere), being able to grow both epiphytically (on the surface of plant tissues) or endophytically (within the tissues) [7]

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