An Overview of Mycorrhiza in Pines: Research, Species, and Applications.

In the latest literature, climate models show that the conditions for pines, spruces, larches, and birches will deteriorate significantly. In Poland, as well as in other European countries, there are already signs of the decline of these species. This review article deals with the symbiotic relationships between fungi and plants, which can hardly be overestimated, using the example of pine trees. These are the oldest known symbiotic relationships, which are of great benefit to both components and can help plants, in particular, survive periods of severe drought and the attack of pathogens on the roots. This article describes symbioses and their causal conditions, as well as the mycorrhizal components of pine trees and their properties; characterizes ectomycorrhizal fungi and their mushroom-forming properties; and provides examples of the cultivation of pure fungal cultures, with particular attention to the specificity of the mycorrhizal structure and its effects on the growth and development of Pinus species. Finally, the role of mycorrhiza in plant protection and pathogen control is described.

Climate, host and geography shape insect and fungal communities of trees.

Non-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 differences 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 affect 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.

Population structure and diversity of the needle pathogen Dothistroma pini suggests human-mediated movement in Europe.

Dothistroma needle blight (DNB) is an important disease of Pinus species that can be caused by one of two distinct but closely related pathogens; Dothistroma septosporum and Dothistroma pini. Dothistroma septosporum has a wide geographic distribution and is relatively well-known. In contrast, D. pini is known only from the United States and Europe, and there is a distinct lack of knowledge regarding its population structure and genetic diversity. The recent development of 16 microsatellite markers for D. pini provided an opportunity to investigate the diversity, structure, and mode of reproduction for populations collected over a period of 12 years, on eight different hosts in Europe. In total, 345 isolates from Belgium, the Czech Republic, France, Hungary, Romania, Western Russia, Serbia, Slovakia, Slovenia, Spain, Switzerland, and Ukraine were screened using microsatellite and species-specific mating type markers. A total of 109 unique multilocus haplotypes were identified and structure analyses suggested that the populations are influenced by location rather than host species. Populations from France and Spain displayed the highest levels of genetic diversity followed by the population in Ukraine. Both mating types were detected in most countries, with the exception of Hungary, Russia and Slovenia. Evidence for sexual recombination was supported only in the population from Spain. The observed population structure and several shared haplotypes between non-bordering countries provides good evidence that the movement of D. pini in Europe has been strongly influenced by human activity in Europe.

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.

Fungal Communities Vectored by Ips sexdentatus in Declining Pinus sylvestris in Ukraine: Focus on Occurrence and Pathogenicity of Ophiostomatoid Species.

Drought-induced stress and attacks by bark beetle Ips sexdentatus currently result in a massive dieback of Pinus sylvestris in eastern Ukraine. Limited and fragmented knowledge is available on fungi vectored by the beetle and their roles in tree dieback. The aim was to investigate the fungal community vectored by I. sexdentatus and to test the pathogenicity of potentially aggressive species to P. sylvestris. Analysis of the fungal community was accomplished by combining different methods using insect, plant, and fungal material. The material consisted of 576 beetles and 96 infested wood samples collected from six sample plots within a 300 km radius in eastern Ukraine and subjected to fungal isolations and (beetles only) direct sequencing of ITS rDNA. Pathogenicity tests were undertaken by artificially inoculating three-to-four-year-old pine saplings with fungi. For the vector test, pine logs were exposed to pre-inoculated beetles. In all, 56 fungal taxa were detected, 8 exclusively by isolation, and 13 exclusively by direct sequencing. Those included nine ophiostomatoids, five of which are newly reported as I. sexdentatus associates. Two ophiostomatoid fungi, which exhibited the highest pathogenicity, causing 100% dieback and mortality, represented genera Graphium and Leptographium. Exposure of logs to beetles resulted in ophiostomatoid infections. In conclusion, the study revealed numerous I. sexdentatus-vectored fungi, several of which include aggressive tree pathogens.

The non-canonical mechanism of ER stress-mediated progression of prostate cancer.

BACKGROUND: The development of persistent endoplasmic reticulum (ER) stress is one of the cornerstones of prostate carcinogenesis; however, the mechanism is missing. Also, alcohol is a physiological ER stress inducer, and the link between alcoholism and progression of prostate cancer (PCa) is well documented but not well characterized. According to the canonical model, the mediator of ER stress, ATF6, is cleaved sequentially in the Golgi by S1P and S2P proteases; thereafter, the genes responsible for unfolded protein response (UPR) undergo transactivation. METHODS: Cell lines used were non-malignant prostate epithelial RWPE-1 cells, androgen-responsive LNCaP, and 22RV1 cells, as well as androgen-refractory PC-3 cells. We also utilized PCa tissue sections from patients with different Gleason scores and alcohol consumption backgrounds. Several sophisticated approaches were employed, including Structured illumination superresolution microscopy, Proximity ligation assay, Atomic force microscopy, and Nuclear magnetic resonance spectroscopy. RESULTS: Herein, we identified the trans-Golgi matrix dimeric protein GCC185 as a Golgi retention partner for both S1P and S2P, and in cells lacking GCC185, these enzymes lose intra-Golgi situation. Progression of prostate cancer (PCa) is associated with overproduction of S1P and S2P but monomerization of GCC185 and its downregulation. Utilizing different ER stress models, including ethanol administration, we found that PCa cells employ an elegant mechanism that auto-activates ER stress by fragmentation of Golgi, translocation of S1P and S2P from Golgi to ER, followed by intra-ER cleavage of ATF6, accelerated UPR, and cell proliferation. The segregation of S1P and S2P from Golgi and activation of ATF6 are positively correlated with androgen receptor signaling, different disease stages, and alcohol consumption. Finally, depletion of ATF6 significantly retarded the growth of xenograft prostate tumors and blocks production of pro-metastatic metabolites. CONCLUSIONS: We found that progression of PCa associates with translocation of S1P and S2P proteases to the ER and subsequent ATF6 cleavage. This obviates the need for ATF6 transport to the Golgi and enhances UPR and cell proliferation. Thus, we provide the novel mechanistic model of ATF6 activation and ER stress implication in the progression of PCa, suggesting ATF6 is a novel promising target for prostate cancer therapy.

Comparative analyses of the Hymenoscyphus fraxineus and Hymenoscyphus albidus genomes reveals potentially adaptive differences in secondary metabolite and transposable element repertoires.

BACKGROUND: The dieback epidemic decimating common ash (Fraxinus excelsior) in Europe is caused by the invasive fungus Hymenoscyphus fraxineus. In this study we analyzed the genomes of H. fraxineus and H. albidus, its native but, now essentially displaced, non-pathogenic sister species, and compared them with several other members of Helotiales. The focus of the analyses was to identify signals in the genome that may explain the rapid establishment of H. fraxineus and displacement of H. albidus. RESULTS: The genomes of H. fraxineus and H. albidus showed a high level of synteny and identity. The assembly of H. fraxineus is 13 Mb longer than that of H. albidus', most of this difference can be attributed to higher dispersed repeat content (i.e. transposable elements [TEs]) in H. fraxineus. In general, TE families in H. fraxineus showed more signals of repeat-induced point mutations (RIP) than in H. albidus, especially in Long-terminal repeat (LTR)/Copia and LTR/Gypsy elements. Comparing gene family expansions and 1:1 orthologs, relatively few genes show signs of positive selection between species. However, several of those did appeared to be associated with secondary metabolite genes families, including gene families containing two of the genes in the H. fraxineus-specific, hymenosetin biosynthetic gene cluster (BGC). CONCLUSION: The genomes of H. fraxineus and H. albidus show a high degree of synteny, and are rich in both TEs and BGCs, but the genomic signatures also indicated that H. albidus may be less well equipped to adapt and maintain its ecological niche in a rapidly changing environment.

Worldwide Genetic Structure Elucidates the Eurasian Origin and Invasion Pathways of Dothistroma septosporum, Causal Agent of Dothistroma Needle Blight.

Dothistroma septosporum, the primary causal agent of Dothistroma needle blight, is one of the most significant foliar pathogens of pine worldwide. Its wide host and environmental ranges have led to its global success as a pathogen and severe economic damage to pine forests in many regions. This comprehensive global population study elucidated the historical migration pathways of the pathogen to reveal the Eurasian origin of the fungus. When over 3800 isolates were examined, three major population clusters were revealed: North America, Western Europe, and Eastern Europe, with distinct subclusters in the highly diverse Eastern European cluster. Modeling of historical scenarios using approximate Bayesian computation revealed the North American cluster was derived from an ancestral population in Eurasia. The Northeastern European subcluster was shown to be ancestral to all other European clusters and subclusters. The Turkish subcluster diverged first, followed by the Central European subcluster, then the Western European cluster, which has subsequently spread to much of the Southern Hemisphere. All clusters and subclusters contained both mating-types of the fungus, indicating the potential for sexual reproduction, although asexual reproduction remained the primary mode of reproduction. The study strongly suggests the native range of D. septosporum to be in Eastern Europe (i.e., the Baltic and Western Russia) and Western Asia.

Looking for relationships between the populations of Dothistroma septosporum in northern Europe and Asia.

Dothistroma septosporum, a notorious pine needle pathogen with an unknown historical geographic origin and poorly known distribution pathways, is nowadays found almost in all areas inhabited by pines (Pinus spp.). The main aim of this study was to determine the relationship between North European and East Asian populations. In total, 238 Eurasian D. septosporum isolates from 11 countries, including 211 isolates from northern Europe, 16 isolates from Russian Far East and 11 isolates from Bhutan were analysed using 11 species-specific microsatellite and mating type markers. The most diverse populations were found in northern Europe, including the Baltic countries, Finland and European Russia. Notably, D. septosporum has not caused heavy damage to P. sylvestris in northern Europe, which may suggest a long co-existence of the host and the pathogen. No indication was obtained that the Russian Far East or Bhutan could be the indigenous area of D. septosporum, as the genetic diversity of the fungus there was low and evidence suggests gene flow from northern Europe to Russian Far East. On the western coast of Norway, a unique genetic pattern was observed, which differed from haplotypes dominating other Fennoscandian populations. As an agent of dothistroma needle blight, only D. septosporum was documented in northern Europe and Asia, while D. pini was found in Ukraine and Serbia.