Periodic Reporting for period 1 - RESISTREE (Identification of Phytophthora resistant beech trees by composition of endophyte communities, lesion formation and phenomics approaches.)
Periodo di rendicontazione: 2020-01-01 al 2021-12-31
Forests cover over 40 % of the EU’s land area, composing a massive, multifunctional green infrastructure with significant economic, social and environmental importance for European citizens. Forest diseases are an increasing threat to forest ecosystems, causing a huge economic and environmental impact on forests worldwide. Invasive alien pathogens and emerging infectious diseases are an unprecedented threat to the capacity of European forests to supply the growing bioeconomy with renewable biomass, carbon sequestration, and other essential ecosystem benefits. One of the most serious concerns in European forests and nurseries is the upsurge of damages caused by invasive, fungal-like, oomycetes Phytophthora species. To strengthen the biosecurity against these pathogens, new, science-based, and socially acceptable forest protection solutions need to be developed. The MSCA-IF RESISTREE project has targeted central knowledge gaps related to a crucial phase of a biological invasion, the establishment phase. Specifically, it has delivered information about the host phenotypic traits and associated mycobiome that can suppress the establishment of Phytophthora species in European forests. We have tested the following hypotheses (1) Endophyte assemblages differ between healthy and Phytophthora-infected trees; (2) Certain endophytic fungi (individual species or groups) limit the growth of Phytophthora-species through different mechanisms; (3) Lesion formation in beech tissues depends on the quality or quantity of endophytic infections in the tissue, and (4) Phytophthora root infection influences the growth and morphology of seedlings before visible symptoms appear.
The research in the RESISTREE project was aimed to strengthen the biosecurity by advancing the current scientific knowledge about the role of microbiome in tree resistance and symptom expression, and by supporting timely development of rapid, non-invasive tools identify infected planting material and resistant phenotypes. The research was organized into 4 working packages.
The first WP was about structural characterization of endophyte community. The intention of the WP1 was to characterize the endophyte fungal community associated with different vitality of the trees. The results showed that the number and abundance of fungal taxa were not different between vitality classes. However, we found differences in the diversity between trees with Phytophthora spp. and trees without them indicating that it was likely that the presence of the pathogen was shaping the composition of the overall microbial community.
The second WP was about the functional characterization of endophytes. The objective of the WP was to describe the antagonistic potential and niche requirements of selected fungal endophytes against the pathogen (several Phytophthora spp). Our results showed that all of the endophytes tested inhibited the growth of at least one of the three pathogens (P. plurivora, P. cambivora, and P. syringae). Preliminary results also showed that pathogens and endophytes used carbon and nitrogen sources in different ways. These results open a door of possibilities for biological control agents and commercial formulations.
The WP3 was about the tissue and cellular level processes in lesion formation. The aim of the WP was to describe the process of lesion formation in woody tissues, with emphasis on possible alterations in fungal communities at the progressing lesion edge. We found out that the community composition of the fungal microbiome was dependent on the presence of the pathogen since control plants differed from inoculated ones. The time of sampling was also a significant factor in our study, indicating that the lesion was correlated with the fungal community composition. The results confirmed our initial hypothesis that the presence of the pathogen changes the fungal community composition around the lesions and over the time of infection.
The WP4 was about phenomics approach as a tool in early diagnosis. The objective was to detect morphological and physiological changes in seedling at early stages of the infection (before lesion formation or other symptoms are visible) using RGB and thermal imaging. The pipelines for acquiring the images were adjusted to the new plant species and images were processed by extracting green leaf area projection of the plant color images. The preliminary results showed that control plants differed from inoculated ones. This approach provided information about disease symptoms not visible by the eye allowing for earlier symptom detection and reducing human subjectivity in trait quantification.
The first WP was about structural characterization of endophyte community. The intention of the WP1 was to characterize the endophyte fungal community associated with different vitality of the trees. The results showed that the number and abundance of fungal taxa were not different between vitality classes. However, we found differences in the diversity between trees with Phytophthora spp. and trees without them indicating that it was likely that the presence of the pathogen was shaping the composition of the overall microbial community.
The second WP was about the functional characterization of endophytes. The objective of the WP was to describe the antagonistic potential and niche requirements of selected fungal endophytes against the pathogen (several Phytophthora spp). Our results showed that all of the endophytes tested inhibited the growth of at least one of the three pathogens (P. plurivora, P. cambivora, and P. syringae). Preliminary results also showed that pathogens and endophytes used carbon and nitrogen sources in different ways. These results open a door of possibilities for biological control agents and commercial formulations.
The WP3 was about the tissue and cellular level processes in lesion formation. The aim of the WP was to describe the process of lesion formation in woody tissues, with emphasis on possible alterations in fungal communities at the progressing lesion edge. We found out that the community composition of the fungal microbiome was dependent on the presence of the pathogen since control plants differed from inoculated ones. The time of sampling was also a significant factor in our study, indicating that the lesion was correlated with the fungal community composition. The results confirmed our initial hypothesis that the presence of the pathogen changes the fungal community composition around the lesions and over the time of infection.
The WP4 was about phenomics approach as a tool in early diagnosis. The objective was to detect morphological and physiological changes in seedling at early stages of the infection (before lesion formation or other symptoms are visible) using RGB and thermal imaging. The pipelines for acquiring the images were adjusted to the new plant species and images were processed by extracting green leaf area projection of the plant color images. The preliminary results showed that control plants differed from inoculated ones. This approach provided information about disease symptoms not visible by the eye allowing for earlier symptom detection and reducing human subjectivity in trait quantification.
The proposed research in RESISTREE project has strengthened the capacity of the host unit and the EU to contribute to fortifying the biosecurity. This has been achieved by advancing the current scientific knowledge about the role of the microbiome in tree resistance and symptom expression, and by supporting the timely development of rapid, non-invasive tools to identify infected planting material and resistant phenotypes. RESISTREE has applied the core microbiome concept across specific host phenotypes, providing an original contribution to current forest pathology theory and supporting the development of microbiome-based solutions in forest protection and tree resistance breeding. The developed conceptual and methodological approach is applicable to other polymicrobial tree–pathogen systems, increasing the relevance of results beyond the project. RESISTREE has brought the current scientific knowledge of lesion formation beyond the state-of-the-art by detailing the microbiome associated with Phytophthora-lesions. The project has developed protocols for the use of non-invasive imaging techniques to monitor the disease progression and host responses, visualizing initial physiological responses to Phytophthora infection and providing technical data for the development of novel tools for the detection of resistant phenotypes. The work carried out has enhanced innovation capacity and created new market opportunities for the biological control of tree pathogens in the forestry sector. The results contribute toward European policy objectives such as the use of non-chemical products (Directive 2009/128/EC and the Green Deal). Potential users of the project results are biological control companies, forest nurseries, forest agencies, etc.