7 research outputs found
Seed quantity affects the fungal community composition detected using metabarcoding
Pest introductions via trade in tree seed may result from a lack of adequate survey and validation protocols. Developing better diagnostic protocols to identify potentially harmful pests and pathogens in forest tree seed is of critical importance. High-throughput sequencing-based barcoding and metabarcoding provide effective tools for screening potentially harmful organisms in various plant materials, including seeds. However, the sample size needed to detect the total microorganism diversity of a community is a major challenge in microbiome studies. In this work, we examined how increasing sample size (ranging between 100 and 1000 seeds) influences diversity of fungal communities detected by high throughput sequencing in Pinus sylvestris seeds. Our results showed that as sample size increased, fungal alpha diversity also increased. Beta-diversity estimators detected significant differences between the mycobiota from different samples. However, taxonomic and functional diversity were not correlated with sample size. In addition, we found that increasing the number of PCR replicates resulted in a higher abundance of plant pathogens. We concluded that for the purpose of screening for potentially harmful pathogens using HTS, greater efforts should be made to increase the sample size and replicates when testing tree seed
Worldwide diversity of endophytic fungi and insects associated with dormant tree twigs
International trade in plants and climate change are two of the main factors causing damaging tree pests (i.e. fungi and insects) to spread into new areas. To mitigate these risks, a large-scale assessment of tree-associated fungi and insects is needed. We present records of endophytic fungi and insects in twigs of 17 angiosperm and gymnosperm genera, from 51 locations in 32 countries worldwide. Endophytic fungi were characterized by high-throughput sequencing of 352 samples from 145 tree species in 28 countries. Insects were reared from 227 samples of 109 tree species in 18 countries and sorted into taxonomic orders and feeding guilds. Herbivorous insects were grouped into morphospecies and were identified using molecular and morphological approaches. This dataset reveals the diversity of tree-associated taxa, as it contains 12,721 fungal Amplicon Sequence Variants and 208 herbivorous insect morphospecies, sampled across broad geographic and climatic gradients and for many tree species. This dataset will facilitate applied and fundamental studies on the distribution of fungal endophytes and insects in trees
Climate, host and geography shape insect and fungal communities of trees
DATA AVAILABITY STATEMENT: The data used in this manuscript, as well as the detail methods on how they were collected and public repositories in which they are stored, are described in FraniÄ et al.40. The raw paired-end Illumina sequencing reads of the ITS2 region are archived at the NCBI Sequence Read Archive under BioProject accession number PRJNA70814822. Assembled herbivorous insect COI sequences are deposited in GenBank database under accession numbers MW441337âMW441767.SUPPORTING INFORMATION: FILE S1: ModelsNon-native pests, climate change, and their interactions are likely to alter relationships between trees
and tree-associated organisms with consequences for forest health. To understand and predict such
changes, factors structuring tree-associated communities need to be determined. Here, we analysed
the data consisting of records of insects and fungi collected from dormant twigs from 155 tree
species at 51 botanical gardens or arboreta in 32 countries. Generalized dissimilarity models revealed
similar relative importance of studied climatic, host-related and geographic factors on diferences
in tree-associated communities. Mean annual temperature, phylogenetic distance between hosts
and geographic distance between locations were the major drivers of dissimilarities. The increasing
importance of high temperatures on differences in studied communities indicate that climate change
could afect tree-associated organisms directly and indirectly through host range shifts. Insect
and fungal communities were more similar between closely related vs. distant hosts suggesting
that host range shifts may facilitate the emergence of new pests. Moreover, dissimilarities among
tree-associated communities increased with geographic distance indicating that human-mediated
transport may serve as a pathway of the introductions of new pests. The results of this study highlight
the need to limit the establishment of tree pests and increase the resilience of forest ecosystems to
changes in climate.https://www.nature.com/srep/Forestry and Agricultural Biotechnology Institute (FABI)SDG-13:Climate actionSDG-15:Life on lan
From leaf to continent: The multi-scale distribution of an invasive cryptic pathogen complex on oak
The spatial distribution and niche differentiation of three closely related species (Erysiphe alphitoides, Erysiphe quercicola and Erysiphe hypophylla) causing oak powdery mildew was studied at scales ranging from the European continent, where they are invasive, to a single leaf. While E. alphitoides was dominant at all scales, E. quercicola and E. hypophylla had restricted geographic, stand and leaf distributions. The large-scale distributions were likely explained by climatic factors and species environmental tolerances, with E. quercicola being more frequent in warmer climates and E. hypophylla in colder climates. The extensive sampling and molecular analyses revealed the cryptic invasion of E. quercicola in nine countries from which it had not previously been recorded. The presence of the three species was also strongly affected by host factors, such as oak species and developmental stage. Segregation patterns between Erysiphe species were observed at the leaf scale, between and within leaf surfaces, suggesting competitive effects
Potential interactions between invasive Fusarium circinatum and other pine pathogens in Europe
Pines are major components of native forests and plantations in Europe, where they have both economic significance and an important ecological role. Diseases of pines are mainly caused by fungal and oomycete pathogens, and can significantly reduce the survival, vigor, and yield of both individual trees and entire stands or plantations. Pine pitch canker (PPC), caused by Fusarium circinatum (Nirenberg and O'Donnell), is among the most devastating pine diseases in the world, and is an example of an emergent invasive disease in Europe. The effects of microbial interactions on plant health, as well as the possible roles plant microbiomes may have in disease expression, have been the focus of several recent studies. Here, we describe the possible effects of co-infection with pathogenic fungi and oomycetes with F. circinatum on the health of pine seedlings and mature plants, in an attempt to expand our understanding of the role that biotic interactions may play in the future of PPC disease in European nurseries and forests. The available information on pine pathogens that are able to co-occur with F. circinatum in Europe is here reviewed and interpreted to theoretically predict the effects of such co-occurrences on pine survival, growth, and yield. Beside the awareness that F. circinatum may co-occurr on pines with other pathogens, an additional outcome from this review is an updating of the literature, including the so-called grey literature, to document the geographical distribution of the relevant pathogens and to facilitate differential diagnoses, particularly in nurseries, where some of them may cause symptoms similar to those induced by F. circinatum. An early and accurate diagnosis of F. circinatum, a pathogen that has been recently introduced and that is currently regulated in Europe, is essential to prevent its introduction and spread in plantings and forests
From leaf to continent: The multi-scale distribution of an invasive cryptic pathogen complex on oak
Worldwide diversity of endophytic fungi and insects associated with dormant tree twigs
International trade in plants and climate change are two of the main factors causing damaging tree pests (i.e. fungi and insects) to spread into new areas. To mitigate these risks, a large-scale assessment of tree-associated fungi and insects is needed. We present records of endophytic fungi and insects in twigs of 17 angiosperm and gymnosperm genera, from 51 locations in 32 countries worldwide. Endophytic fungi were characterized by high-throughput sequencing of 352 samples from 145 tree species in 28 countries. Insects were reared from 227 samples of 109 tree species in 18 countries and sorted into taxonomic orders and feeding guilds. Herbivorous insects were grouped into morphospecies and were identified using molecular and morphological approaches. This dataset reveals the diversity of tree-associated taxa, as it contains 12,721 fungal Amplicon Sequence Variants and 208 herbivorous insect morphospecies, sampled across broad geographic and climatic gradients and for many tree species. This dataset will facilitate applied and fundamental studies on the distribution of fungal endophytes and insects in trees.Datapaper</p