New saga in Finland: The rise of Diplodia sapinea in Scots pine.

The intensity of fungal virulence is likely to increase in northern forests as climate change alters environmental conditions, favoring pathogen proliferation in existing ecosystems while also facilitating their expansion into new geographic areas. In Finland, Diplodia sapinea, the causal agent of disease called "Diplodia tip blight", has emerged as a new pathogen within the past few years. To reveal the current distribution of the novel fungal pathogen, and the effect of temperature and rainfall on its distribution, we utilized citizen science for the detection and collection of symptomatic Scots pine (Pinus sylvestris) shoots.

Complex transmission of partiti-, ambi- and ourmiaviruses in the forest pathogen Heterobasidion parviporum.

Utilizing Heterobasidion partitivirus 13 strain an1 (HetPV13-an1) and 15 strain pa1 (HetPV15-pa1) in co-infection is considered a potential biocontrol approach against Heterobasidion root and butt rot. Both partitiviruses mediate debilitating effects in most Heterobasidion host isolates and are generally transmitted efficiently between host strains. In this investigation, we conducted transmission experiments in the laboratory (in vitro) using several H.

Virus transmission frequencies in the pine root rot pathogen Heterobasidion annosum.

The combined use of Heterobasidion partitiviruses 13 and 15 (HetPV13-an1 and HetPV15-pa1) is considered a promising biocontrol approach against Heterobasidion root and butt rot. In a previous study, the transmission frequency of HetPV15-pa1 was found to be higher from a double partitivirus-infected donor than from a single partitivirus-infected donor. In this study, we included a wider array of recipient isolates to assess whether the phenomenon is widespread across different host strains and conducted transmission experiments on artificial media (in vitro) using a total of 45 different H.

Integrating viruses into soil food web biogeochemistry.

The soil microbiome is recognized as an essential component of healthy soils. Viruses are also diverse and abundant in soils, but their roles in soil systems remain unclear. Here we argue for the consideration of viruses in soil microbial food webs and describe the impact of viruses on soil biogeochemistry.

Meeting report: The first soil viral workshop 2022.

Soil viral ecology is a growing research field; however, the state of knowledge still lags behind that of aquatic systems. Therefore, to facilitate progress, the first Soil Viral Workshop was held to encourage international scientific discussion and collaboration, suggest guidelines for future research, and establish soil viral research as a concrete research area. The workshop took place at Søminestationen, Denmark, between 15 and 17th of June 2022.

High Diversity of Novel Viruses in the Tree Pathogen Revealed by High-Throughput Sequencing of Total and Small RNA.

, an oomycete pathogen causing root and trunk rot of different tree species in Asia, was shown to harbor a rich diversity of novel viruses from different families. Four isolates collected from in a semi-natural montane forest site in Vietnam were investigated for viral presence by traditional and next-generation sequencing (NGS) techniques, i.e.

Discovery and Community Dynamics of Novel ssRNA Mycoviruses in the Conifer Pathogen .

species are highly destructive basidiomycetous conifer pathogens of the Boreal forest region. Earlier studies have revealed dsRNA virus infections of families and in strains, and small RNA deep sequencing has also identified infections of members in these fungi. In this study, the virome of was examined for the first time by RNA-Seq using total RNA depleted of rRNA.

The virome from a collection of endomycorrhizal fungi reveals new viral taxa with unprecedented genome organization.

Mutualistic plant-associated fungi are recognized as important drivers in plant evolution, diversity, and health. The discovery that mycoviruses can take part and play important roles in symbiotic tripartite interactions has prompted us to study the viromes associated with a collection of ericoid and orchid mycorrhizal (ERM and ORM, respectively) fungi. Our study, based on high-throughput sequencing of transcriptomes (RNAseq) from fungal isolates grown in axenic cultures, revealed in both ERM and ORM fungi the presence of new mycoviruses closely related to already classified virus taxa, but also new viruses that expand the boundaries of characterized RNA virus diversity to previously undescribed evolutionary trajectories.

Mixed infection by a partitivirus and a negative-sense RNA virus related to mymonaviruses in the polypore fungus Bondarzewia berkeleyi.

Virus communities of forest fungi remain poorly characterized. In this study, we detected two new viruses co-infecting an isolate of the polypore fungus Bondarzewia berkeleyi using high-throughput sequencing. One of them was a putative new partitivirus designated as Bondarzewia berkeleyi partitivirus 1 (BbPV1), with two linear dsRNA genome segments of 1928 and 1863 bp encoding a putative RNA-dependent RNA polymerase (RdRP) of 591 aa and a putative capsid protein of 538 aa.

Virus population structure in the ectomycorrhizal fungi Lactarius rufus and L. tabidus at two forest sites in Southern Finland.

Lactarius fungi belong to the Russulaceae family and have an important ecological role as ectomycorrhizal symbionts of coniferous and deciduous trees. Two Lactarius species, L. tabidus and L.

Microscopical Detection of Cell Death Processes During Scots Pine Zygotic Embryogenesis.

Programmed cell death (PCD) processes are essential in the plant embryogenesis. To understand how PCD operates in a developing seed, the dying cells need to be identified in relation to their surviving neighbors. This can be accomplished by the means of in situ visualization of fragmented DNA-a well-known hallmark of PCD.

Viruses of fungi and oomycetes in the soil environment.

Soils support a myriad of organisms hosting highly diverse viromes. In this minireview, we focus on viruses hosted by true fungi and oomycetes (members of Stamenopila, Chromalveolata) inhabiting bulk soil, rhizosphere and litter layer, and representing different ecological guilds, including fungal saprotrophs, mycorrhizal fungi, mutualistic endophytes and pathogens. Viruses infecting fungi and oomycetes are characterized by persistent intracellular nonlytic lifestyles and transmission via spores and/or hyphal contacts.

Genome sequencing and population genomic analyses provide insights into the adaptive landscape of silver birch.

Silver birch (Betula pendula) is a pioneer boreal tree that can be induced to flower within 1 year. Its rapid life cycle, small (440-Mb) genome, and advanced germplasm resources make birch an attractive model for forest biotechnology. We assembled and chromosomally anchored the nuclear genome of an inbred B.

Expression of catalase and retinoblastoma-related protein genes associates with cell death processes in Scots pine zygotic embryogenesis.

Background: The cell cycle and cellular oxidative stress responses are tightly controlled for proper growth and development of Scots pine (Pinus sylvestris L.) seed. Programmed cell death (PCD) is an integral part of the embryogenesis during which megagametophyte cells in the embryo surrounding region (ESR) and cells in the nucellar layers face death.

Phenolic compounds and expression of 4CL genes in silver birch clones and Pt4CL1a lines.

A small multigene family encodes 4-coumarate:CoA ligases (4CLs) catalyzing the CoA ligation of hydroxycinnamic acids, a branch point step directing metabolites to a flavonoid or monolignol pathway. In the present study, we examined the effect of antisense Populus tremuloides 4CL (Pt4CL1) to the lignin and soluble phenolic compound composition of silver birch (Betula pendula) Pt4CL1a lines in comparison with non-transgenic silver birch clones. The endogenous expression of silver birch 4CL genes was recorded in the stems and leaves and also in leaves that were mechanically injured.

Interaction with ectomycorrhizal fungi and endophytic Methylobacterium affects nutrient uptake and growth of pine seedlings in vitro.

Tissues of Scots pine (Pinus sylvestris L.) contain several endophytic microorganisms of which Methylobacterium extorquens DSM13060 is a dominant species throughout the year. Similar to other endophytic bacteria, M.

Evolution, three-dimensional model and localization of truncated hemoglobin PttTrHb of hybrid aspen.

Thus far, research on plant hemoglobins (Hbs) has mainly concentrated on symbiotic and non-symbiotic Hbs, and information on truncated Hbs (TrHbs) is scarce. The aim of this study was to examine the origin, structure and localization of the truncated Hb (PttTrHb) of hybrid aspen (Populus tremula L. × tremuloides Michx.

The responses of Vitreoscilla hemoglobin-expressing hybrid aspen (Populus tremula × tremuloides) exposed to 24-h herbivory: expression of hemoglobin and stress-related genes in exposed and nonorthostichous leaves.

The responses of transcriptome and phenolic compounds were determined with Populus tremula L. × Populus tremuloides Michx. expressing the hemoglobin (Hb) of Vitreoscilla (VHb) and non-transformant (wt) line.

Polyamine metabolism during exponential growth transition in Scots pine embryogenic cell culture.

Polyamine (PA) metabolism was studied in liquid cultures of Scots pine (Pinus sylvestris L.) embryogenic cells. The focus of the study was on the metabolic changes at the interphase between the initial lag phase and the exponential growth phase.

Long-term cryopreservation of Greek fir embryogenic cell lines: recovery, maturation and genetic fidelity.

In coniferous species, including Greek fir (Abies cephalonica Loud), the involvement of somatic embryo plants in breeding and reforestation programs is dependent on the success of long-term cryostorage of embryogenic cultures during clonal field testing. In the present study on Greek fir, we assayed the recovery, morphological characteristics and genetic fidelity of embryogenic cell lines 6 and 8 during proliferation and maturation after long-term cryostorage. Our results indicate successful recovery of both cell lines after 6 years in cryostorage.

Dealing with the problem of non-specific in situ mRNA hybridization signals associated with plant tissues undergoing programmed cell death.

Background: In situ hybridization is a general molecular method typically used for the localization of mRNA transcripts in plants. The method provides a valuable tool to unravel the connection between gene expression and anatomy, especially in species such as pines which show large genome size and shortage of sequence information.

Results: In the present study, expression of the catalase gene (CAT) related to the scavenging of reactive oxygen species (ROS) and the polyamine metabolism related genes, diamine oxidase (DAO) and arginine decarboxylase (ADC), were localized in developing Scots pine (Pinus sylvestris L.

Phenolic compounds in ectomycorrhizal interaction of lignin modified silver birch.

Background: The monolignol biosynthetic pathway interconnects with the biosynthesis of other secondary phenolic metabolites, such as cinnamic acid derivatives, flavonoids and condensed tannins. The objective of this study is to evaluate whether genetic modification of the monolignol pathway in silver birch (Betula pendula Roth.) would alter the metabolism of these phenolic compounds and how such alterations, if exist, would affect the ectomycorrhizal symbiosis.