Cork oak endophyte community as a way to control diseases in a climate changing world

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The influence of bioclimate on soil microbial communities of cork oak

Publication . Costa, Daniela; Tavares, Rui Manuel; Baptista, Paula; Lino-Neto, Teresa

Background: Soil microbiomes are important to maintain soil processes in forests and confer protection to plants against abiotic and biotic stresses. These microbiomes can be affected by environmental changes. In this work, soil microbial communities from different cork oak Portuguese forests under different edaphoclimatic conditions were described by using a metabarcoding strategy targeting ITS2 and 16S barcodes. Results: A total of 11,974 fungal and 12,010 bacterial amplicon sequence variants (ASVs) were obtained, revealing rich and diverse microbial communities associated with different cork oak forests. Bioclimate was described as the major factor influencing variability in these communities (or bioclimates/cork oak forest for fungal community), followed by boron and granulometry. Also, pH explained variation of fungal communities, while C:N ratio contributed to bacterial variation. Fungal and bacterial biomarker genera for specific bioclimates were described. Their co-occurrence network revealed the existence of a complex and delicate balance among microbial communities. Conclusions: The findings revealed that bacterial communities are more likely to be affected by different edaphoclimatic conditions than fungal communities, also predicting a higher impact of climate change on bacterial communities. The integration of cork oak fungal and bacterial microbiota under different bioclimates could be further explored to provide information about useful interactions for increasing cork oak forest sustainability in a world subject to climate changes.

2022Journal article

Open access

Phylogenetic analysis and genetic diversity of the xylariaceous ascomycete Biscogniauxia mediterranea from cork oak forests in different bioclimates

Publication . Costa, Daniela; Ramos, Vitor; Tavares, Rui Manuel; Baptista, Paula; Lino-Neto, Teresa

Cork oak is a tree species with ecological importance that contributes to economic and social development in the Mediterranean region. Cork oak decline is a major concern for forest sustainability and has negative impacts on cork oak growth and production. This event has been increasingly reported in the last decades and seems to be related with climate changes. Biscogniauxia mediterranea is an endophytic fungus of healthy cork oak trees that turns into a pathogen in trees weaken by environmental stress. Understanding the drivers of B. mediterranea populations diversity and differentiation is expected to allow a better control of cork oak decline and preserve forest sustainability. Endophyte isolates from different cork oak forests were identified as B. mediterranea and their genetic diversity was evaluated using phylogenetic and microsatellite-primed PCR analyses. Genetic diversity and variability of this fungus was correlated with environmental/phytosanitary conditions present in forests/trees from which isolates were collected. High genetic diversity and variability was found in B. mediterranea populations obtained from different forests, suggesting some degree of isolation by distance. Bioclimate was the most significant effect that explained the genetic variability of B. mediterranea, rather than precipitation or temperature intensities alone or disease symptoms. These findings bring new implications for the changing climate to cork oak forests sustainability, cork production and quality.

2022Journal article

Open access

Cork oak endophytic fungi as potential biocontrol agents against biscogniauxia mediterranea and diplodia corticola

Publication . Costa, Daniela; Tavares, Rui Manuel; Baptista, Paula; Lino-Neto, Teresa

An increase in cork oak diseases caused by Biscogniauxia mediterranea and Diplodia corticola has been reported in the last decade. Due to the high socio-economic and ecologic importance of this plant species in the Mediterranean Basin, the search for preventive or treatment measures to control these diseases is an urgent need. Fungal endophytes were recovered from cork oak trees with different disease severity levels, using culture-dependent methods. The results showed a higher number of potential pathogens than beneficial fungi such as cork oak endophytes, even in healthy plants. The antagonist potential of a selection of eight cork oak fungal endophytes was tested against B. mediterranea and D. corticola by dual-plate assays. The tested endophytes were more efficient in inhibiting D. corticola than B. mediterranea growth, but Simplicillium aogashimaense, Fimetariella rabenhorstii, Chaetomium sp. and Alternaria alternata revealed a high potential to inhibit the growth of both. Simplicillium aogashimaense caused macroscopic and microscopic mycelial/hyphal deformations and presented promising results in controlling both phytopathogens’ growth in vitro. The evaluation of the antagonistic potential of non-volatile and volatile compounds also revealed that A. alternata compounds could be further explored for inhibiting both pathogens. These findings provide valuable knowledge that can be further explored in in vivo assays to find a suitable biocontrol agent for these cork oak diseases.

2020Journal article

Open access

Diversity of fungal endophytic community in Quercus suber L. and detection of opportunistic phytopathogenic fungi

Publication . Costa, Daniela; Cunha, Joana; Tavares, Rui Manuel; Baptista, Paula; Lino-Neto, Teresa

Cork oak (Quercus suber L.) is a species of high ecological importance in Mediterranean Basin and has high relevance for Portuguese economy due to cork production and processing. The sustainability of cork oak is currently being threatened by reduction of water availability that would increase the occurrence of diseases. Charcoal disease, caused by the fungus Biscogniauxia mediterrânea, leads to death of the tree. Diplodia corticola is involved in various diseases considered responsible for the decline of cork oak in Mediterranean Basin. To identify endophytic fungi in cork oak, including these opportunistic pathogens, four sites of continental Portugal (Bragança, Geres, Alcobaça and Grândola) with differences in water availability were selected to carry out the collection of biological material. The community of fungal endophytes of leaves, st^ms and roots was evaluated. The roots displayed a more diverse fungal community than the aboveground organs. Although no disease symptoms were detected in studied cork oaks, the referred pathogenic fungi were essentially affecting stems and leaves. In general, Grândola presented the highest colonization frequency and diversity of endophytes, while Alcobaça had the lowest. From ali studied sites, cork oaks from Geres showed the most distinct community and did not presentthose pathogens. D. corticola only infected southern regions, while S. mediterrânea also infected trees in Bragança. The exclusive presence of both pathogens in aboveground organs and the absence of visible disease symptoms in ali studied cork oaks encourage the searching of adequate biocontrol agents from the endophytic community for restricting these diseases in cork oak.

2017Conference object

Open access