Seminar Abstracts

1. Seminar on Forest and Plant Health
5 April 2018
Natural Resources Institute Finland, Viikki, Helsinki
Chondrostereum purpureum on birch (Betula sp.) stump. (Photo: Leena Hamberg)

2. Seminar on Forest and Plant Health, 5 April 2018
Natural Resources Institute Finland, Viikki, Helsinki
Endophytes in forest protection - from promise to practice
Johanna Witzell
Swedish University of Agricultural Sciences, Southern Swedish Forest Research Center, Box
49, 23053 Alnarp, Sweden
E-mail: johanna.witzell@slu.se
Recent advances in molecular techniques have revealed a high diversity of asymptomatic,
internal (endophytic) fungi in plants, including forest trees. Several studies have provided
evidence for their potential in plant protection. For instance, in vitro antagonistic effects of
endophytes on pathogens, based on chemical interactions, mycoparasitism or substrate
competition have been demonstrated, and occurrence of certain endophytes or endophyte
communities has been linked to resistance phenotypes of trees. Yet, forest protection
applications based on endophytes have remained rare. Identified challenges in putting the
promise to practice include the problems in assay-based selection, poor understanding of
replacement dynamics, difficulty of integrating the endophytic layer to tree improvement
programs, and concern about introductions. In addition, factors such as lack of host
specificity of many endophytes, the slowness of their potential protective effect and general
lack of knowledge about the biology and environmental control in trees is limiting the
development of commercially viable forest protection solutions. A profound hinder along the
way may also be our expectation that endophyte-based solutions should be designed
according to the currently (and historically) dominant standards for plant protection solutions,
for instance products that are applied as therapeutic treatments and specifically target a
disease-causing organism. New insights could be gained when framing the discussion
according to a three horizon approach, a foresight tool developed for innovation and risk
management that can help us to structure our thinking about the unknown future in ways that
promote innovations. Ultimately, it could be possible to incorporate endophyte-based
solutions to forest stand management through ecological engineering.

3. Seminar on Forest and Plant Health, 5 April 2018
Natural Resources Institute Finland, Viikki, Helsinki
Interfertility between European and North American isolates of
Chondrostereum purpureum
Jarkko Hantula1
, Leena Hamberg1
, Paul de la Bastide2
, Will Hintz2
, Simon
Francis Shamoun3
and Marina Brandtberg4
1
Natural Resources Institute Finland, P.O. Box 2 (Latokartanonkaari 9), FI-00790 Helsinki,
Finland
2
Department of Biology, Centre for Forest Biology, University of Victoria, P.O. Box 1700,
STN CSC, Victoria, B.C. V8W 2Y2, Canada
3
Natural Resources Canada, Canadian Forest Service, Pacific Forestry Centre, 506 West
Burnside Road, Victoria, B.C., V8Z 1M5, Canada
4
Verdera Ltd., P.O. Box 5, Kurjenkellontie 5 B, FI-02270, Espoo, Finland
Email: jarkko.hantula@luke.fi
Chondrostereum purpureum is a potential biocontrol agent against hardwood sprouting, and a
registered product is available in Canada. Also in Europe local strains of this species have
been shown to be efficient against sprouting of several tree species, and traditional cross-
breeding has resulted in an elite isolate with superior control efficacy. Regarding the potential
biorisks it has been shown that C. purpureum does not have asexual spore production and
therefore its spread cannot result in uncontrolled clonal dispersal. Also the degree of genetic
differentiation in northern Europe has been shown to be low. In this study we tested the
conspecificity of European and North American C. purpureum by pairing experiments and
analyses of the resulting offspring, and showed that the two populations belong to the same
biological species with normal meiosis although genetic and limited phenotypic
differentiation was observed.
Literature: Hamberg, L., De la Bastide, P., Hintz, W., Shamoun, S.F., Brandtberg, M.,
Hantula, J. 2018. Interfertility and genetic variability among European and North American
isolates of the basidiomycete fungus Chondrostereum purpureum. Fungal Biol.
10.1016/j.funbio.2018.03.009

4. Seminar on Forest and Plant Health, 5 April 2018
Natural Resources Institute Finland, Viikki, Helsinki
Coniothyrium stem canker of Eucalyptus: which one and where
did it come from?
Ximena Silva1
, Jolanda Roux2
, Mike Wingfield2
, Ginna Granados2
, Alberto Yanosky3
,
Alfredo Gryciuk4
and Fred O. Asiegbu1
1
Department of Forest Sciences, University of Helsinki, Latokartanonkaari 7, P.O. Box 27,
00790, Helsinki, Finland
2
Forestry and Agricultural Biotechnology Institute, at the University of Pretoria in South
Africa.
3
Guyra Paraguay Association, Birdlife in Paraguay
4
National Service for Plant and Seed Quality and Health (SENAVE), Paraguay
Email: ximena.silvapalacios@helsinki.fi
Eucalyptus is one of the most planted genus worldwide, particularly in the tropics, and the
plantation of this genus is spreading considerably in the Southern Hemisphere. Eucalyptus
plantations are relevant for economies in this region and also for the several multinational
companies that are investing resources in these plantations. Although initially these
plantations were disease free, in the last few years, exotic pathogens arrived to the Southern
Hemisphere and at the same time local pathogens adapted to Eucalyptus. One of these
pathogens causes what is known as Coniothyrium canker, a disease that can reduce the value
of the timber and increase the production costs when working with pulp production. This
disease was initially found in South Africa and believed to be local. Further studies indicated
that there were two species causing similar symptoms and only distinguishable by molecular
methods, these species are Teratosphaeria zuluensis and T. gauchensis, which have been
reported different countries and normally do not overlap. Research suggests Teratosphaeria
zuluensis might be local to South East Asia while T. gauchensis could be local to South
America. In this research we collected samples from Eucalyptus affected by Coniothyrium
canker from different areas in Paraguay and used culture based methods and molecular
method for isolate identification. We found that the species causing Coniothyrium canker in
Paraguay is Teratosphaeria zuluensis. To increase understanding on this pathogen in
Paraguay, we studied the genetic population using 8 microsatellite markers designed for T.
zuluensis. We found that the Paraguayan population of Teratosphaeria zuluensis is clonal,
and therefore has been recently introduced into the country. Comparing our dataset with those
from African populations of T. zuluensis revealed they are different genotypes and therefore
the origin of this fungus in Paraguay remains unknown.

5. Seminar on Forest and Plant Health, 5 April 2018
Natural Resources Institute Finland, Viikki, Helsinki
Dual RNAseq analysis provides new insights into interactions
between Norway spruce and necrotrophic pathogen
Heterobasidion annosum s.l.
Andriy Kovalchuk
Department of Forest Sciences, University of Helsinki, Latokartanonkaari 7, P.O. Box 27,
00790, Helsinki, Finland
E-mail: andriy.kovalchuk@helsinki.fi
Members of Heterobasidion annosum species complex are often considered as some of the
most devastating fungal pathogens in boreal conifer forests. They cause root and butt rot of
conifer trees, resulting in considerable economic losses due to decrease in timber yield and
quality and higher tree mortality. Disease management strategies are currently focused at the
stump treatment and the harvesting guidelines aiming to prevent the infection of stumps after
tree felling. However, there is no treatment available for infected trees, and selection of tree
genotypes showing increased resistance against Heterobasidion infection is considered as an
important approach in combatting the disease. In order to get better understanding of
interactions between Heterobasidion fungi and their hosts and of the mechanisms underlying
tree resistance to root and butt rot, we performed dual RNA-seq analysis of host and pathogen
transcriptome in naturally infected Norway spruce trees. We also analyzed terpenoid content
of the spruce trees. Our data provide support for the contribution of the components of
flavonoid pathway to the resistance of Norway spruce against Heterobasidion infection. We
also identified a set of candidate genes, which might be involved in the higher level
regulation of defense responses in spruce trees and found indications for a possible role of
abscisic acid (ABA) signaling in this process. Results of this study should contribute to better
understanding of defense strategies employed by conifer trees against Heterobasidion
infection. Identified candidates deserve further evaluation as potential markers for higher
resistance against root and butt rot.

6. Seminar on Forest and Plant Health, 5 April 2018
Natural Resources Institute Finland, Viikki, Helsinki
Bacterial biota and correlation with host terpenoid profiles of
asymptomatic and symptomatic Norway spruce infected by
Heterobasidion sp.
Fei Ren1,2
, Andriy Kovalchuk1
, Mukrimin Mukrimin1,3
, Mengxia Liu1
, Zhen Zeng1
, Rajendra
P. Ghimire4
, Minna Kivimäenpää4
, Jarmo K. Holopainen4
, Hui Sun5
and Fred O. Asiegbu1
1
Faculty of Agriculture and Forestry, Department of Forest Sciences, University of Helsinki,
P.O. Box 27, FIN-00014, Helsinki, Finland
2
Forestry experiment center of north China, Chinese Academy of Forestry, 102300, Beijing,
China
3
Department of Forestry, Universitas Hasanuddin, Jln. Perintis Kemerdekaan Km. 10, 90245,
Makassar, Indonesia
4
Department of Environmental and Biological Sciences, University of Eastern Finland, P.O.
Box 1627, FIN-70211 Kuopio, Finland
5
Collaborative Innovation Center of Sustainable Forestry in Southern China, College of
Forestry, Nanjing Forestry University, Nanjing, China
E-mail: fei.ren@helsinki.fi
Forest trees live in close association with microbial symbionts, which may affect the host
fitness, productivity and tolerance against biotic and abiotic stressors. The composition of
forest tree microbial communities could be influenced by tree genotypes and environmental
factors, but little is known about the effect of tree pathogens on the structure of these
communities. In this study, we investigated the structure of bacterial communities associated
with different tissues of asymptomatic and symptomatic (Heterobasidion-rotten) Norway
spruce [Picea abies (L.) Karst.] trees. Our results demonstrated that each of the investigated
tissues (root, bark, down stem, upper stem and needles) harbored a unique bacterial
assemblage. Additionally, we performed profiling of terpenoid compounds present in spruce
xylem and phloem. Total concentrations of monoterpenes and sesquiterpenes were
considerably higher in asymptomatic trees. Our results provide an important insight into the
diversity of bacteria associated with Norway spruce trees. This is the first comprehensive
study on bacteria biota on conifer tree tissues. We hope the datasets will be a huge resource
for the tree biology and forest pathology community as well as plant science community.

7. Seminar on Forest and Plant Health, 5 April 2018
Natural Resources Institute Finland, Viikki, Helsinki
Genome-wide DNA methylation in conifer pathogen
Heterobasidion parviporum
Zhen Zeng1
, Tommaso Raffaello, Mengxia Liu, Zilan Wen and Fred O. Asiegbu
1
Department of Forest Sciences, University of Helsinki, Latokartanonkaari 7, P.O. Box 27,
00790, Helsinki, Finland
E-mail: zhen.zeng@helsinki.fi
Heterobasidion parviporum is the causative agent of root and butt rot disease of Norway
spruce. Conidia and mycelia are two important developmental stages in the asexual life cycle
of this species. This pathogen also has a dual nutritional lifestyles (necrotrophy and
saprotrophy). A major feature of this species is that it can flexible switch lifestyles depending
on what materials it has encountered. DNA methylation is one of the main epigenetic
modifications in eukaryotic genome. In fungi, methylation is more frequently found in
transposable elements (TEs) as one way of genome defense, where it is thought to play a role
in preventing the duplication of TEs and silencing of DNA repeats. The hypothesis of this
project is that the lifestyle transition and fungal development are governed by differential
expression of genes, which are further regulated by DNA methylation. The aims of this
project are to profile the genome-wide distribution of methylation in H. parviporum and to
determine the implications of DNA methylation in the development and different lifestyles in
this species. In this project, total RNA and genomic DNA were extracted from diverse
developmental stages of H. parviporum for RNA-seq and Bisulfite sequencing, respectively.
Bioinformatic analysis revealed that methylation occurred in any DNA context including
both CpG and non-CpG contexts, but with preference for CpG context in H. parviporum.
Further studies are ongoing.

8. Seminar on Forest and Plant Health, 5 April 2018
Natural Resources Institute Finland, Viikki, Helsinki
Interactions of Polyporales fungi: enzyme activities, VOCs and
decay patterns on spruce wood
Tuulia Mali1
, Mari Mäki2,3
, Firoz Shah1
, Mari Mäkinen1
, Hans Mattila1
, Heidi Hellén4
, Jussi
Heinonsalo2,4
, Jaana Bäck2,3
and Taina Lundell1
1
Fungco group, Department of Microbiology and 2
Department of Forest Sciences, Faculty of
Agriculture and Forestry, University of Helsinki
3
Institute for Atmospheric and Earth System Research, University of Helsinki
4
Finnish Meteorological Institute, Kumpula Campus; Finland
Emails: tuulia.mali@helsinki.fi, taina.lundell@helsinki.fi
Forests are important carbon sinks in the terrestrial ecosystems. In boreal forests, the amount
of dead wood can be as high as the living tree biomass. Dead wood is an important habitat for
animals like insects and birds; for microbes, such as saprotrophic, pathogenic, and
ectomycorrhizal fungi, for bacteria, protists, viruses, and algae; for lichens and mosses etc.
Fungal communities in dead wood are dynamic. These dynamic interactions can be
mutualistic, neutral or antagonistic. We have studied the influence of Fomitopsis pinicola, a
common brown rot Basidiomycota species of Polyporales encountered in boreal and
temperate forests as a saprotroph and tree pathogen, on hyphal growth and enzyme activity
patterns with five white rot fungal species, including the Polyporales species Phlebia radiata
and Trichaptum abietinum. The fungi were cultivated in various species combinations under
controlled conditions on e.g. wood-supplemented medium [1]. In fungal co-cultures on agar
media, F. pinicola was a supreme colonizer advancing over hyphae of the white rot species
[1]. Other white rot species were confronted by P. radiata with dense mycelial front. In liquid
and solid-state cultures, substantial production of oxalic acid by F. pinicola was the main
acidifying component. In conclusion, enzyme activity dynamics over time are directed by the
fungal combinations, and species co-cultures also express. In another study, evidence of
Fenton reaction-type biochemistry was obtained for the brown-rot species F. pinicola [2].
Preliminary analyses on emitted VOCs (volatile organic compounds) from the solid wood-
substrate cultivations demonstrate a distinct effect of white rot compared to brown rot fungal
wood-decay strategy on the VOC profiles. We aim at characterizing these compounds, and
compilation of the laboratory data to field studies.
[1] Mali T, Kuuskeri J, Shah F, Lundell T (2017) PLoS ONE 12(9): e0185171
[2] Shah F, Mali T, Lundell T (2018) Appl Environ Microbiol 84(8): e02662-17

9. Seminar on Forest and Plant Health, 5 April 2018
Natural Resources Institute Finland, Viikki, Helsinki
It's complicated – top-to-toe phenotyping reveals variable trait
responses to environment in a tree population
Matti Salmela, Sannakajsa Velmala and Taina Pennanen
Natural Resources Institute Finland, P.O. Box 2 (Latokartanonkaari 9), FI-00790 Helsinki,
Finland
Email: matti.salmela@luke.fi
Root traits vary among species and along ecological gradients, but the possibility of within-
species genetic diversity in belowground growth on a fine spatial range remains unexplored.
Further, evidence for the root-shoot growth synchronisation is inconclusive. In this
multifaceted experiment, we estimated phenotypic plasticity, quantitative genetic variation and trait
spectra in roots and shoots in a southern Finnish population of Norway spruce (Picea abies).
Seedlings from 15 maternal families grew in three soil treatments under two temperature treatments
that simulated growing seasons with differing mean temperatures. We phenotyped over 600 seedlings
from top to toe for 25 traits, including size, architecture and morphology of intact roots, and shoot size
and autumn phenology. Our results show that various traits across the seedling, including phenology,
were influenced by the interaction of temperature with soil. Genetic diversity in the population was
abundant, with environment-dependent genetic variances in some traits caused by differences in
phenotypic plasticity among families. We also discovered multiple distinct trait spectra in the
population, with size-related root and shoot traits varying together but independently from root
economic traits (architecture and morphology), shoot phenology and growth allocation. Our findings
indicate that genetic variation in belowground traits may be substantial within natural populations and
that accurate response predictions to climate change can be convoluted by complex interactions of
environmental factors, disparate trait responses to environmental changes, multiple independent trait
spectra and the context-dependence of natural genetic variation in adaptive traits.