9 December: Susanna Saari

Grass endophyte in food chain – friend or foe?

Susanna Saari

University of North Carolina at Greensboro, NC, USA


Plants harbour many different microbes, fungi and bacteria that take advantage of their hosts. However, the host can also benefit from these organisms, which are known as endophytes. I have studied obligate endosymbiosis and the nature of the relationship between the symbiont and the host, using fungal Neotyphodium endophyte-grass symbiosis as a model system. According to my PhD thesis research, endophyte infections were found to be common in the meadow fescue cultivars in Finland, although the frequency varied considerably both between and within cultivars. European tall fescue cultivars were practically endophyte-free. Microfungi were common in natural meadow fescue populations found in the Åland Islands, Estonia, the coastal area of Södermanland in Sweden, and Gotland. The high level of infection indicates that endophytes are beneficial to their natural grass hosts at least in these areas. The reason behind the varying infection levels found in cultivars may be that where an endophyte affects one of the agriculturally important characteristics of its host grass, plant breeders may have inadvertently promoted or restricted the prevalence of the endophyte by favouring or rejecting individual plant characteristics. The toxins produced by endophytes affect the pest-resistance of grass in many ways. The study concluded that endophytes increased the resistance of meadow fescue to bird cherry-oat aphids, overriding the effects of seed lot and cultivar. Endophytes did not affect the body mass or population size of voles that consume endophyte-infected grass, but they did reduce the voles' mobility. In predation tests, immobility and calmness appeared to protect voles from weasels, as they were no longer able to detect voles among the grass. Fungal endophytes can also affect grass reproduction and growth. The fungi appeared to increase seed production in meadow fescue but to stunt growth after mowing in some circumstances. Endophytes appear to affect the competition between certain growth functions inside the plant. Endophytes have been found to benefit their hosts especially in fertile agricultural environments. In natural infertile environments, however, the fungus can be an enemy. The plant has to share the little resources that it collects from the soil with the fungus, which in turn may produce fewer toxins. This prevents the fungus from protecting its host effectively against pests. Endophytes have caused serious toxic symptoms in cattle fed on infected grass in the US and in New Zealand. Seed production companies in these countries now routinely examine animal feed for endophytes in order to prevent these problems from recurring. Endophytes affect many agriculturally important characteristics of the host grass, which is why they should be acknowledged in agricultural management in Europe as well.

25 November: Søren Rosendahl

Stochastic processes and human activity are important drivers in mycorrhizal evolution.

Søren Rosendahl

Department of Biology, University of Copenhagen, Denmark

The plant root symbiotic arbuscular mycorrhizal fungi are common in most ecosystems. Several cosmopolitan species are found on all continents except the Antartica. Three hypotheses may explain this worldwide distribution. Either speciation occurred before the continents separated 120 mill yr ago, or the distribution is a result of human mediated dispersal related to agriculture. Finally, morphologically defined species may encompass several local endemic species. To test these hypotheses three genes were sequenced from 82 isolates of Glomus mosseae originating from six continents. Sequences were analyzed for geographic subdivision and estimation of migration between continents. Coalescent analyses estimated divergence and age of mutations. Baysian coalescent modeling was used to reveal important past population changes in the global population. The sequence data showed no geographical structure, with identical genotypes found on different continents. Coalescence analyses indicated a recent diversification in the species, and the data could be explained by a recent population expansion in G.mosseae. The results suggest that speciation and the range expansion happened much later than continental spread and that human activity may have had a major impact on the dispersal and the population structure of the fungus. At the local scale analyses of haplotype networks suggested a subdivision of G. mosseae haplotypes between fields with different land use history. The results show that agricultural practices differently affect both the abundance and the population genetic structure of arbuscular mycorrhizal fungi.

11 November: Laura Rose

Land-use intensification in grassland ecosystems: effects from leaf to ecosystem

Laura Rose

Department of Ecology and Ecosystem Research, University of Goettingen, Germany

In the last 50 years, land-use changes in temperate grassland ecosystems occurred either by land-use intensification, i.e. increased fertilization, cutting frequency and stocking rate, or by abandonment of non-profitable sites mostly on low productive soils. Such land-use changes can have profound effects on the species composition, the amount of standing and produced biomass, and on biogeochemical cycles. I am going to present results from the GrassMan experiment, an interdisciplinary meadow experiment at the University of Göttingen, which is designed to investigate the effects of plant biodiversity, fertilizer application and different cutting frequencies on several aspects of grassland functioning.

Fertilizer application and alterations of the cutting frequency severely affect functional leaf traits: NPK-fertilization leads to generally higher leaf-level water use efficiency (WUE), accompanied by an increase in the specific leaf area and leaf nitrogen concentration. Cutting effects are more species specific. Besides these effects on leaf trait values, fertilization additionally alters the interspecific relationships between leaf traits.

Although the increase in leaf-level water use efficiency with fertilization is mirrored by an increase in WUE on the stand level, fertilization leads to higher evapotranspiration rates and thereby decreases ground-water recharge. This is mostly attributed to the higher amount of biomass produced in fertilized compared to unfertilized meadows. Irrespective of its positive effect on aboveground biomass production, fertilization increases nitrogen leaching.

28 October: Justin Thomas Wynns

Status of an ongoing systematic study of Plagiothecium.

Justin Thomas Wynns

dept. Agriculture and Ecology, Copenhagen University


Plagiothecium is a conspicuous and widely distributed genus of pleurocarpous mosses, typically growing on soil or humus in forests, heaths and swamps. The genus is well characterized morphologically by plants that are mostly medium-sized to large, flattened, and highly glossy, with decurrent leaves. Many species produce characteristic small uniseriate gemmae in abundance.

Plagiothecium appears to be a mostly natural genus that includes several species-complexes and some anomalous species. A large number of taxa have been described, and some are very poorly known. Although several excellent regional treatments of the genus exist, Plagiothecium has not been monographed on a worldwide scale. The goal of my study is to obtain a molecular phylogeny of Plagiothecium that will serve as the systematic basis for a projected worldwide monograph.

Pleurocarpous mosses have undergone rapid morphological diversification in recent evolutionary history, and DNA sequence data can be very uniform in this group. To identify the most useful genetic loci for evolutionary reconstruction in Plagiothecium, I have sequenced a number of different loci (mostly chloroplast, some nuclear) for a small number of taxa. In this Ph.D. Status Seminar, I discuss the results of this ongoing initial phase of my study, including the taxonomic conclusions that are emerging.

14 October: Toby Kiers

Reciprocal Rewards in the Rhizosphere: Underground markets and the evolution of cooperation in plant-fungal mutualisms.

Toby Kiers

Free University Amsterdam, Department of Animal Ecology, Faculty of Earth and Life Sciences, Netherlands

Associating with microbes in the rhizosphere can have both costs and benefits for host plants. Because associations generally involve multiple microbial genotypes varying in mutualistic benefit, a potential tragedy of the commons can arise. How do plants maintain cooperation with the most beneficial rhizosphere microbes over the course of evolution? Specific mechanisms may be employed that reduce the fitness benefits to microbes from “cheating”. In the mycorrhizal mutualism, the fungal symbiont cannot be “enslaved.” Rather, the mutualism is evolutionarily stable because control is bidirectional, and partners offering the best rate of exchange are rewarded. The existence of underground biological markets will be discussed.

10 June: Katharine Ann Marske

Historical Biogeography

Katharine Ann Marske

Ecology and Evolution, Department of Biology, Copenhagen University


Phylogeographic structure and its underlying causes are not necessarily shared among community members, with important implications for using individual organisms as indicators for ecosystem evolution, such as the identification of forest refugia. Over 1000 mitochondrial DNA (COI) sequences and newly developed coalescent phylogeography models were used to construct geo-spatial histories for four co-distributed New Zealand forest beetles. These methods identify historical dispersal patterns via ancestral state reconstruction. Ecological niche models were used to reconstruct the potential geographic distribution of each species during the Last Glacial Maximum (LGM). Combined results yielded a complex picture of temperate forest community evolution. Each species shared some features of its LGM distribution or range expansion pathways with every other, but no general patterns were detected among all four. These results indicate that forest species retreated into and expanded out from the same refugia by a variety of routes, rather than travelling together as an intact forest community, which has important implications for using individual taxa to detect historical ecosystem dynamics.

27 May: Koen Verhoeven

Epigenetic inheritance in asexual dandelions

Koen Verhoeven

Netherlands Institute of Ecology, dept. Terrestrial Ecology, the Netherlands


Epigenetic mechanisms such as DNA methylation can cause stable but reversible changes in gene activity without changes in the underlying DNA sequence. Recent studies in plants have shown that DNA methylation patterns can be modified by environmental and genomic stresses, that they can be transmitted between generations and that they can cause heritable trait variation in absence of genetic (sequence) variation. This implies that heritable variation may not be fully understood from genetic variation alone. To date, however, the evolutionary relevance of epigenetic inheritance is unknown and much of the underlying mechanisms remains poorly understood. To gain better insight in the factors that generate heritable methylation variation I used methylation-sensitive AFLP markers to evaluate the epigenetic consequences of ecological stress exposure and polyploidization events in apomictic dandelions. Especially stress exposure triggered methylation changes and most of these changes were faithfully transmitted to unexposed offspring. This suggests that heritable methylation variation is readily generated that is independent of genetic variation between individuals, which can have consequences for the adaptive potential of asexual species such as dandelions. I will briefly sketch some perspectives for linking epigenetics and ecological research, which can improve our understanding of the evolutionary relevance of epigenetic inheritance.

13 May: Jørgen Jensen

A journey into the past ‒ the History of Botany at LIFE

Jørgen Jensen

dept. Agriculture and Ecology, Copenhagen University


Jørgen Jensen will review the important people and their contributions to plant science and education at LIFE. He will also discuss the organisational changes that have taken place during the long history of botanical study at this institution. This seminar will be held in Danish.

Baseret på et stort antal skriftlige kilder og egen erindring har Jørgen Jensen udarbejdet et antal lister, der belyser personale, lokalisering, økonomi, undervisning og forskning ved den botaniske enhed under Den kongelige Veterinær- og Landbohøjskole i perioden fra højskolens oprettelse i 1858 til dens ophør som selvstændig enhed i 2006. Baggrundsmaterialet er primært KVL’s årsberetninger, samt et stort materiale fra Rigsarkivet såsom undervisningsprotokoller, gamle byggesager og ikke mindst mødereferater fra den periode hvor universiteterne blev ledet af faglige og kollegiale råd og udvalg.

29 April: Jacob Weiner

Size and Reproduction within Plant Populations

Jacob Weiner

dept. Agriculture and Ecology, Copenhagen University


The quantitative relationship between size and reproductive output is a central aspect of a plant’s strategy: the conversion of growth into fitness. Since plant allocation changes with size, we take an allometric perspective and review existing data on the relationship between individual vegetative (V, x-axis) and reproductive (R, y-axis) biomass within plant populations, rather than analyzing biomass ratios such as reproductive effort (R/[R+V]).

The allometric relationship between R and V among individuals within a population is most informative when cumulative at senescence (‘total R–V relationship’), as this represents the potential reproductive output of individuals given their biomass. Earlier measurements may be misleading if plants are at different developmental stages and therefore have not achieved the full reproductive output their size permits. Much of the data that have been considered evidence for plasticity in reproductive allometry are actually evidence for plasticity in the rate of growth and development.

Although a positive x intercept implies a minimum size for reproducing, a plant can have a threshold size for reproducing without having a positive x-intercept.

Most of the available data are for annual and monocarpic species whereas data on long-lived iteroparous plants are scarce. We find three common total R–V patterns: short-lived, herbaceous plants and clonal plants usually show a simple, linear relationship, either (1) passing through the origin or (2) with a positive x intercept, whereas larger and longer-lived plants often exhibit (3) classical log-log allometric relationships with slope < 1. While the determinants of plant size are numerous and interact with one another, the potential reproductive output of an individual is primarily determined by its size and allometric program, although this potential is not always achieved.

8 April: Ib Linde-Laursen

My life with Hordeum chromosomes

Ib Linde-Laursen

dept. Agriculture and Ecology, Copenhagen University

The genus Hordeum (Barley) belongs to the tribe Triticeae of the Poaceae. The tribe comprises the cereal crops wheat, barley and rye and many important forage grass species, in all about 350 species. The genus Hordeum includes 32 species and altogether 45 taxa occurring in temperate regions of the world except in Australia. Relatively most species are found in South America. The species have 14, 28 or 42 large chromosomes in somatic cells. The chromosomes, excepting those wearing ‘satellites’ are morphologically so similar within chromosome complements (karyotypes) that they can only be identified reliably using special procedures producing patterns of cross-bands in the chromosomes. In the inbreeding Hordeum vulgare (cultivated barley) use of Giemsa C-banding demonstrates 7 different banding patterns, each pattern occurring in two of barley’s 14 chromosomes, i.e. in one of the 7 pairs. The bands may vary in size and position although not to a degree which renders it impossible to recognize the basic banded karyotype of H. vulgare in barley lines (varieties). Banding patterns may establish the parental origin of their chromosomes. Bands show Mendelian segregation and can be used to assign genes to chromosome regions. Each of the 45 Hordeum taxa has its specific basic banded karyotype, but this may not be so dissimilar relative to those of other taxa that it is possible to distinguish taxa on this basis. Interspecific hybrids among H. vulgare and Hordeum taxa with 28 or 42 chromosomes may show partial or complete elimination of 7 chromosomes, generally those of H. vulgare corresponding to one genome. Based on chromosome elimination patterns a hypothesis is put forward that the chromosomes have an orderly arrangement within the genome. In hybrids with the related Psathyrostachys fragilis (14 chromosomes) and in the interspecific Hordeum hybrids, the H. vulgare chromosomes are on an average lying closer to the cell centre than the chromosomes of the other parent supporting that the two genomes occupy different compartments.

25 March: Christoph Scherber

Effects of plant species richness on plant-herbivore and multitrophic interactions

Christoph Scherber

dept. Crop Sciences, Agroecology, Georg-August-University Göttingen, Germany

Biodiversity is rapidly declining, yet we still don't know if this decline leads to consistent changes in ecosystems. While the past decades have seen enormous efforts to study the effects of biodiversity loss on ecosystem processes, many studies still focused on plant productivity and related variables. Thus, the response of many components of terrestrial ecosystems to biodiversity loss have remained largely unexplored.

In this talk, I will take a systems perspective on plant biodiversity and show how different groups of organisms respond to changes in plant species richness. From soil microbes to aboveground pollinators, show that losses of plant diversity cascade up and down in food webs. Biodiversity loss is negative for many groups and processes, but there are exceptions.

In conclusion, the studies I present in the talk show that plants indeed form the basis for aboveground and belowground food webs, and that losses in plant diversity ultimately lead to indirect co-extinctions in many different groups of organisms.

11 March: Bjarne Larsen

Crocus – Evolution and Domestication

Bjarne Larsen

dept. Agriculture and Ecology, Copenhagen University

The genus Crocus contains about 80 species of corm-bearing perennial geophytes. Crocus grows generally in mountainous areas from sea level up to 2500 m, mostly on limestone ground in winter rain areas around the Mediterranean Sea. The largest diversity of species is found in Turkey, but species are found all the way from Portugal /Spain in west to Western China in east. Characteristic for most species is a limited geographical distribution where species have adapted to specific habitats. The flowering season of Crocus is almost throughout the year depending on species. The diversity of a number of the spring-flowering species is used for ornamental purposes. Hybrids between C. biflorus and C. chrysanthus have arisen during the last hundred years, resulting in a wide range of flower colors and shapes, which has gained popularity as early spring garden plants.

One of the most valuable crocuses, is the saffron crocus, Crocus sativus. This autumn-flowering species are grown for the world’s most expensive spice, saffron. C. sativus has been cultivated 4000 years back in time but is not known to occur in the wild. The ancestors of this triploid (2n=24), sterile species is not known, but C. cartwrightianus, a closely related diploid (2n=16) species from the Attica peninsula of Greece is believed to have taken part in ancient hybridization events resulting in C. sativus. This unique hybridization event has since then given corms to all the world’s saffron crocuses by vegetative reproduction.

The enormous diversity of Crocus represents a history of massive hybridization and specialization. Inter- and intraspecific variation suggests that the genus during evolution has been exposed to huge adaption demands and selection pressure.

25 February: Dag Terje Filip Endresen

Notice: the seminar will be in the lecture room in the greenhouse basement , Rolighedsvej 21 (not in øvelsessal 1)!

Predictive link between crop traits and ecoclimatic description of the original collecting site.

Dag Terje Filip Endresen

Nordic Genetic Resource Center (NordGen), Alnarp, Sweden


Biodiversity includes a rich diversity of different species adapted to a wide range of ecological conditions. Populations of species adapted to a subset of the species habitat are called ecotypes or ecospecies. Typically ecotypes show distinct phenotypic properties in response to their spesific ecological environment. Traditional crop cultivars can be seen as the agricultural equivalent of the ecotypes in wild species. Crop plants have evolved in response to the ecoclimatic and agricultural environment as human civilization developed and spread out across the planet. This phase of spread and adaption to new ecological conditions and new agricultural practizes resulted in a very large genetic diversity represented by distinct landraces of the crop species and has steadily progressed during the last 10 000 years. Modern plant breeding has reversed this steady increase in crop genetic diversity by the development of uniform modern high yielding cultivars outcompeting the diverse mosaic of previous landraces grown in the farming landscape around the world. During in particular the last fifty years this alarming effect of genetic erosion in the cultivated crops became increasingly more visible resulting in the systematic collection and conservation of the previous crop genetic diversity represented by the disapearing landraces. Under the coordination of the Food and Agriculture Organization of the United Nations (FAO) a network of international and national genebanks were established based on the model of the Russian Institute of Plant Industry located in Saint Petersburg (initiated in 1894 as the Bureau of Applied Botany).

These collections of crop genetic resources are today a valuable source of new genetic variation for economically important traits, including resistance to crop diseases. New sources of useful crop traits are often identified through evaluation in field trials, some of which may require special treatments such as inoculation for screening purposes. This has tremendous implications as it incurs costs. Further, the number of relevant accessions in genebank collections available to be evaluated for a specific trait is often substantially larger than the capacity or resources of the evaluation project. Thus, finding the genebank accessions most likely to posses the desired trait can be compared to searching for a needle in a haystack. The Focused Identification of Germplasm Strategy (FIGS) is an approach used to select subsets of germplasm from genetic resource collections in such a way as to maximize the likelihood of capturing a spesific trait at a higher frequency than if the subset had been selected at random. Michael Mackay originally proposed this subset selection strategy in 1990. Michael Mackay and Kenneth Street developed the strategy further in 2004 including the official naming as Focused Identification of Germplasm Strategy (FIGS).

The FIGS strategy uses a range of methods to link the expression of a specific trait (of a target crop) with the ecogeographic parameters of the original collection site. The results from a number of recent studies using the FIGS approach show that the climate layers from freely available ecogeographic databases are well suited to model and predict the reaction in these crops to biotic stress traits and other economically valuable crop traits. This result has the potential to improve the efficiency of field screening trials to find novel sources of economically valuable crop traits.

11 February: Nils Cronberg

Fertilization syndromes in bryophytes: Parallels to pollination syndromes in vascular plants.

Nils Cronberg

dept. Ecology, Section of Plant Ecology and Systematics, Lund University, Sweden

As a heritage from their algal ancestors, bryophytes (mosses, liverworts and hornworts) and early-divergent tracheophytes (lycophytes and pteridophytes) have motile sperm that need a water surface for transportation. This is considered to be a major evolutionary constraint in terrestrial environments. Thus, any character that improves fertilization efficiency would be strongly selected. In fact, several suites of characters that promote cross-fertilization, comparable to pollination syndromes in vascular plants, occur in various bryophytes. Splash-cup mechanisms take advantage of the force of falling water drops to increase the dispersal distance of sperm, which are hitchhiking with the split droplets. Phyllodioicy involves dwarf-sized males, which germinate and grow on normal-sized female plants, adjacent to female reproductive structures, thereby facilitating out-crossing at minimal sperm dispersal distances. Mechanisms that discharge airborne sperm are known from some liverworts. We have recently proved that microarthropods (springtails and mites) can assist in the transfer of sperm of the moss Bryum argenteum and thus mediate fertilization. We also have demonstrated that microarthopods are specifically attracted to fertile moss shoots. From these experiments we concluded that an animal-mediated fertilization syndrome similar to pollination in flowering plants occur in mosses. Bryophytes and microarthropods are evolutionarily much older than flowering plants and this fertilization syndrome is therefore potentially a precursor to pollination syndromes in flowering plants.

28 January: Stina Christensen & Christine Heimes

A reciprocal resistance system in two types of Barbarea vulgaris - An ecogenetic perspective.

Stina Christensen & Christine Heimes

dept. Agriculture and Ecology, Copenhagen University


Barbarea vulgaris (Brassicaceae) is a biennial or perennial herbal plant species, with a natural distribution in western Eurasia. In Denmark, the subspecies B.vulgaris ssp. arcuata occurs in two types, a hairy (Pubescent) P-type and a hairless (Glabrous) G-type. Populations of P- and G-type plants are found in all parts of Denmark, growing predominantly in separate patches. Hybrids between P- and G-type are rare, probably due to a partial reproductive barrier. The two plant types differ in morphological, cytological and chemical characters, and G-type plants are resistant to the flea beetle Phyllotreta nemorum, whereas P-type plants are susceptible. In contrast, G-type plants are susceptible to the oomycete pathogen Albugo candida, whereas P-type plants seem to be resistant.

Our talk will be based on the objectives of our PhD projects, aiming to entangle the role of resistance mechanisms in B. vulgaris from an ecological and genetic point of view:

• Is the geographical distribution of the two types caused by their belonging to two different evolutionary groups that occupied different refugia during the last ice age?

• Is the distribution of the P- and G-type populations in the landscape determined by different adaptations to local environmental conditions?

• Is resistance polymorphism in Danish B. vulgaris populations maintained by selection pressure exerted by the flea beetle P. nemorum and the oomycete A. candida?

• Is there a hybridization barrier and do hybrids have lower survival rates or lower fertility?

• Where in the genome does the Albugo-resistance map to, and what are the active defense compounds?

14 January: Inger Åhman

Plant to plant communication via volatiles

Inger Åhman

dept. Plant Breeding and Biotechnology, Swedish University of Agricultural Sciences, Alnarp

About 30 years ago two independent studies showed that volatiles from damaged plants may induce resistance to herbivores in neighbouring undamaged plants. These results were initially much debated, but were later confirmed in other plant species as well. During the last decade also volatiles from apparently undamaged plants have been found to induce changes in neighbouring plants, however only in certain genotype combinations. Efforts to unravel the mechanisms for this will be presented, using barley and the bird cherry – oat aphid as test organisms. Possibilities to apply these results for plant protection purposes will be presented.