Botany Seminars

A joint seminar of the section Systematics, Biodiversity & Evolution of Plants, the Botanische Staatssammlung München and the Botanical Garden München-Nymphenburg

When?

Wednesdays at 4:15pm (during the semester)

Where?

Small lecture hall (Room 109) in the Botanical Institute, Menzinger Str. 67, 80638 München.

Program

19 April 2023: Dr. John Clarke. Department of Earth and Environmental Sciences, Palaeontology & Geobiology, LMU Munich, Germany.

Host: Prof. Dr. Gudrun Kadereit

26 April 2023: Dr. Fatemeh Ghaderiardakani. Institute for Inorganic and Analytical Chemistry, Friedrich Schiller University Jena, Germany.

Three become one in a tripartite community: Reassessing the collaborative adaptation of Ulva (Chlorophyta) and its microbiome to cold temperatures in Antarctica

Chemical communication using infochemical-mediated strategies plays an essential role in ecological interactions in marine ecosystem. These chemical signals in algal–bacterial interaction are not still completely known but given that bacteria release algal growth- and morphogenesis-promoting factors (AGMPFs) required for (green) macroalgae growth and development, adaptive responses to environmental stressors must be considered within the community structure.
To evaluate the contribution of macroalgae and its microbiome to various stress factors particularly temperature, the reductionistic model system of the tripartite community formed by U. mutabilis and its two essential bacteria, Roseovarius sp. strain MS2 and Maribacter sp. strain MS6, which release all essential AGMPFs, was investigated. This analysis will let us to determine the stress response of each algal and bacterial symbionts within this cross-kingdom interactions and will help to understand the ecological success of Ulva.
I will present the morphogenetic effect of recently isolated bacteria from Potter Cove, King George Island (Isla 25 de Mayo) in Antarctica, on the model system U. mutabilis Føyn starting with axenic gametes. The results indicate that cold-adapted bacteria release sufficient amounts of AGMPFs, inducing cell differentiation, and cell division in axenic cultures. In particular, metabolite profiling of polar low molecular weight compounds revealed insights into the species-dependent cold stress response of the green seaweed holobiont Ulva (Chlorophyta).
Integrating the chemical ecology to aquatic-microbiome investigations will allow us to further explore underlying adaptation and acclimation mechanisms in macroalgae to stress situations.

fatemeh2

Host: Dr. Andreas Beck

03 May 2023: Prof. Dr. Markus A. Koch. COS Universität Heidelberg, Germany.

Evolution at the dry limits - tillandsiales in the hyperarid Atacama Desert

Epiarenic (sand-growing) Tillandsia vegetation in the hyperarid and arid region of the Chilean-Peruvian Atacama Desert represents an extreme case of adaptation in plant species-poor ecosystems. The involved species exist at the limit of terrestrial life and form mono/oligo-specific and very characteristic structures within the landscape. Covering thousands of square kilometers they represent the major carbon sink in the hyperarid Atacama core. The various Tillandsia species and respective vegetation may have evolved and adapted independently to this extreme environment in various ways. The most abundant vicariant diploid species are T. landbeckii in Chile and T. purpurea in Peru. Spatio-temporally varying distribution range overlaps may have caused adaptive gene flow between different species leading to present day gene pools and inter-species gene flow crossing even ploidy levels. This mechanism highlights a strategy to evolve and adapt more rapidly to environmental changes in extreme arid and hyperarid habitats, and provides an opportunity for Tillandsia populations to efficiently conserve new genotypes via subsequent clonal propagation.

atacama
Tillandsia

Host: Prof. Dr. Gudrun Kadereit

10 May 2023: Dr. Robert Lücking. Botanischer Garten und Botanisches Museum, Freie Universität Berlin, Germany.

Foliicolous lichens and the phyllosphere: a microcosmos in tropical rain forests

Foliicolous lichens inhabit the surface of living leaves of vascular plants. Together with bryophytes (mostly liverworts of the family Lejeuneaceae), green algae (predominantly Trentepohliaceae), cyanobacteria (chiefly Scytonema), superficial fungi (e.g., Microthyriaceae), bacteria, and invertebrates (psocids, mites, insect larvae, nematodes), they constitute the phyllospere, a diverse miniature ecosystem best developed in tropical rain forests. Notable features of foliicolous lichens include their short life cycles, in combination with often diminutive thalli, fixed to the substrate by a thin layer of mucilage, as well as specialized reproductive structures, such as hyphophores, campylidia, and disc-shaped isidia. Many species are believed to be widely and even pantropically distributed, presumably reflecting long-distance dispersal or high phylogenetic age. However, molecular phylogenetic studies suggest a high level of endemism and a high degree of cryptic speciation, such as in the families Gomphillaceae (e.g., Gyalectidium) and Strigulaceae (e.g., Strigula). There is a strong decline of species richness with increasing altitude and seasonality, most taxa being confined to lowland rain forests. A single leaf the size of a hand may support up to 50 species and more than 300 species may occur within a single locality. This impressive small-scale diversity, together with the high community dynamics, provide an excellent model to investigate mechanisms that maintain high small scale diversity in tropical ecosystems, such the Huston-Connell intermediate disturbance model and density-dependent feedback interactions. Within the rain forest, three associations of foliicolous lichens can be distinguished: in the shady understory, in natural light gaps, and in the canopy. The nature of the phorophyte has little influence on species composition but affects diversity. Closely related species, such as in the genus Mazosia, are often ecologically equivalent and co-occur side-by-side on the same leaves, a phenonemon possibly explained by an evolutionary species pump mechanisms. Due to their sensitivity to abiotic factors and environmental changes, foliicolous lichens can be used to indicate microclimatic parameters, as well as the degree of disturbance of a rain forest site. Species of certain genera, such as Badimia, are excellent indicators of well-preserved rain forest.

luecking3

Host: Prof. Dr. Silke Werth

17 May 2023: Dr. Nicolai M. Nürk. Biogeography lab, BayCEER, University of Bayreuth, Germany.

What is diversification and how should we study it?

Two fundamental macroevolutionary processes affect the dramatic differences in biodiversity on Earth: Diversification within and dispersal between areas. Mutation, recombination, and genetic drift contribute at microevolution scales and depend on demographic, ecological, and geographic settings. Today, evolutionary processes can be studied within phylogenetic frameworks in great detail. Current findings on model congruence, however, raised concerns about the general identifiability of most fundamental evolutionary parameters, such as the rates of speciation and extinction. I will discuss existing approaches to studying species diversification in flowering plants, using empirical working examples of how combined information on ecology, geography, and phylogeny can be used to infer basic principles of species evolution.

nuerk

Host: Dr. Diego Morales-Briones

24 May 2023: Dr. Karol Krak. Czech University of Life Sciences, Prague, Czech Republic.

Molecular phylogeny and evolutionary trends in Chenopodium album aggregate

krak The genus Chenopodium L. s. lat., comprises approximately 150 species distributed worldwide. Some of these species, especially those belonging to the C. album agg. represent vigorous weeds and one of the most widespread synanthropic plants on Earth. The C. album agg. represents a taxonomically extremely challenging group composed of many, only weakly differentiated and morphologically overlapping entities with wide distributions and high levels of phenotypic plasticity. The group represents a diploid-polyploid complex with diploid, tetraploid, hexaploid and decaploid taxa.
To elucidate the evolutionary relationships within the group and identify the origins of allopolyploids we applied a wide range of cytogenetic (chromosome counting, flow-cytometry, fluorescent in situ hybridization), molecular (sequencing of cpDNA, ITS, cloning of low-copy nuclear genes) and phylogenomic (HybSeq) approaches on Eurasian and North American representatives of the group.
The following evolutionary scheme was inferred. The C. album agg. is composed of eight major evolutionary lineages. Five of them are represented by extant diploid taxa and show distinct genome sizes. The remaining three groups do not match any existing diploids and were delimited based on the sequences found in the genomes of polyploids, indicating the involvement of already extinct or so far unsampled lineages. All polyploid species were found to be hybrids between these main lineages. We identified allopolyploids for almost all subgenome combinations in Eurasia, indicating that allopolyploidisation is a major driving force of this group’s evolution, at least in the Old World. Contrarily, only a single subgenome combination was found in American polyploids. Here, the most plausible scenario of diversification involves adaptive radiation and speciation at diploid level.

Host: Dr. Anže Žerdoner Čalasan

07 June 2023: Dr. Alyssa Weinstein. Australian National University, Australia, and Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services, Bonn, Germany.

Floral ecotypes in the sexually deceptive Warty Hammer Orchid

Sexually deceptive orchids are unusual among plants in that closely related species typically attract different pollinator species using contrasting blends of floral volatiles. Therefore, intraspecific variation in pollinator attraction may also be underpinned by differences in floral volatiles. Pollinator choice trials revealed the presence of three floral ecotypes within the Warty Hammer Orchid, Drakaea livida, that each attracts a different species of thynnine wasp as a pollinator. Floral ecotypes differed in chemical volatile composition, with a high degree of separation evident in principal coordinate analysis. Some compounds that differed between ecotypes, including pyrazines and (methylthio)phenols, were found to be electrophysiologically active in pollinator antennae. MaxEnt species distribution models revealed that each ecotype has a different predicted geographic range, with small areas of overlap at the range margins. One ecotype is known from just ten populations over a limited geographic area, the majority of which has been cleared for agriculture and urban development. While there was broad overlap between the ecotypes in individual morphological traits, multivariate analysis of morphological traits provided correct assignment of ecotype in 87% of individuals. Using the labellum of pollinated flowers, screening for volatile chemical compounds associated with particular ecotypes returned an even higher correct assignment rate, of 96.5%. Based on differences in pollinator response and floral volatile profile, the ecotypes represent distinct entities and should be treated as such in conservation management. The use of volatiles from the labellum of recently pollinated flowers is an effective way to determine the ecotype of unknown individuals of D. livida, with minimal impact on the flowering plant.

weinstein

Host: Dr. Elizabeth Joyce

14 June 2023: Dr. Renata Callegari Ferrari. Department of Crop Nutrition and Forest Genetics Department, Georg-August-Universität Göttingen, Germany.

Investigating the alternation between C₄ and CAM in Portulaca oleracea

The Portulaca genus is remarkable since all its C₄ and C₃-C₄ intermediate species studied up to date undergo CAM induction upon water deficit. Among those, P. oleracea is a C₄-annual cosmopolite usually found growing in human-disturbed areas. It has unresolved taxonomic issues, being defined as a noxious weed to agriculture, but concomitantly used as medicine and food in some countries. During my PhD, we characterized in detail the central genetic machinery involved in both CCMs in P. oleracea, using transcriptome data associated with phylogenetic and physiological analyses. Stems in P. oleracea are C₃-performing, and we showed they are ontogenetically induced to CAM. We also explored the morphophysiological plasticity of the species, characterizing CAM in different subspecies originated in different parts of the world. Given the facultative nature of the C₄-CAM transition in P. oleracea, a complex regulatory network fine-tuning the expression of each or both CCMs in response to the environmental cues is expected. Therefore, in addition, we investigated the circadian clock mechanisms, hormonal signaling and transcription factors involved in regulating the C₄-CAM transition, all of it converging into optimized molecular strategies and protocols to enable the use of P. oleracea as a convenient C₄-CAM system. I will provide an overview of the mentioned works, which were developed during my PhD.