Kiel Plant Center

KPC Mini Symposium June 2020

Jun 24, 2020 from 10:00 AM to 11:15 AM


This is an online event. For access details please email

Welcome: Prof. Dr. Thorsten Reusch (GEOMAR Kiel)

Session Chair: Dr. Angela Stevenson (GEOMAR Kiel)

Speaker: Lei Yu
Affiliation: GEOMAR Kiel, Marine Evolutionary Ecology Group (PhD student with Prof. Dr. Thorsten Reusch)

Title: Somatic genetic drift and multilevel selection in a clonal seagrass

All multicellular organisms are genetic mosaics owing to somatic mutations. The accumulation of somatic genetic variation in clonal species undergoing asexual (or clonal) reproduction may lead to phenotypic heterogeneity among autonomous modules (termed ramets). However, the abundance and dynamics of somatic genetic variation under clonal reproduction remain poorly understood. Here we show that branching events in a seagrass (Zostera marina) clone or genet lead to population bottlenecks of tissue that result in the evolution of genetically differentiated ramets in a process of somatic genetic drift. By studying inter-ramet somatic genetic variation, we uncovered thousands of single nucleotide polymorphisms that segregated among ramets. Ultra-deep resequencing of single ramets revealed that the strength of purifying selection on mosaic genetic variation was greater within than among ramets. Our study provides evidence for multiple levels of selection during the evolution of seagrass genets. Somatic genetic drift during clonal propagation leads to the emergence of genetically unique modules that constitute an elementary level of selection and individuality in long-lived clonal species.

Speaker: Dr. Amine Hassani
Affiliation: Kiel University, Environmental Genomics Group (Postdoc with Prof. Dr. Eva Stukenbrock)

Title: A fungal avirulence protein induces a shift in the wheat microbiome and metabolome

In nature, plants coexist with diverse microbial communities, such as bacteria and fungi. The association between the plant and these microorganisms forms an ecological unit termed the metaorganism or holobiont. Plant-associated microbes can have beneficial, neutral or deleterious impact on their host fitness. Zymoseptoria tritici is a fungal pathogen that could infect different wheat cultivars and causes significant yield loses. This fungus secretes a set of effector proteins to avoid or suppress the plant immune system. Among these proteins, Z. tritci secretes the avirulence protein AvrStb6. Wheat cultivars that encode for the resistance protein Stb6 show qualitative and quantitative resistance against Z. tritici in the field. In our previous work, we have demonstrated that Z. tritici induces a systemic susceptibility and shift in the wheat microbiome and metabolome. Here, we investigated the role of the fungal avirulence protein, AvrStb6, in mediating the shift in phyllosphere microbiota of two wheat cultivars either resistant or sensitive to Z. tritici. We combine microbial communities profiling with comparative metabolomics analyses. Current results indicate that both fungal strains, wild-type and avrStb6-deficient mutant, induce shift in the leaf microbiota of both test wheat cultivars. Further, this avirulance protein seems to modulate the plant immune system. These results indicate that AvrStb6 could directly interfere with leaf microbiota and/or indirectly by modulating the plant immune system.

Speaker: Dr. Jay Jethva
Affiliation: Kiel University, Institute of Plant Developmental Biology and Physiology (Postdoc with Prof. Dr. Margret Sauter)

Title: Control of mitochondrial ROS is crucial for survival of re-oxygenation in Arabidopsis

Flooding is a biphasic stress with initial reduction of molecular oxygen (O2) and light during submergence followed by increase in O2 and light during reoxygenation. When oxygen is limited, the mitochondrial electron transport chain (mETC) gets reduced and NADH accumulates as electrons are not transferred to the final electron acceptor O2. Upon re-oxygenation, the reductive power can lead to excess ROS formation. However, cellular mechanisms managing this process are still not well understood. Plant mitochondria possess an alternative mETC consisting of alternative NADH dehydrogenases (NDs) and ALTERNATIVE OXIDASE (AOX). We observed that knockout of the internal NDs NDA1 and NDA2 in Arabidopsis thaliana reduced, whereas overexpression increased plant survival of re-oxygenation in the light. Reduced survival correlated with a reduced photosynthetic recovery in NDA knockout seedlings, connecting the alternative mETC to chloroplast function. NDA1 and NDA2 do not control cellular ATP or the NADH/NAD redox balance. Rather, they contain ROS formation during re-oxygenation. Our data suggest that control of ROS by the alternative mETC is crucial for photosynthetic recovery following re-oxygenation and for seedling survival of re-oxygenation stress.

Closing remarks

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