The Graduate School LSM offers an international doctoral programme to motivated and excellent academically qualified next generation researchers at one of Europe’s top Universities. LSM calls for doctoral applications on a yearly basis, open from the 1st of October until the 30th of November 2022. Doctoral positions in Plant Genetics are available in the research group of: Prof. Dr. Martin Parniske:

Learn more about the projects:

1. Spatio-temporal dynamics in the composition and function of the CCaMK/CYCLOPS complex, the master regulator of plant root symbioses

Plant root symbioses with arbuscular mycorrhiza (AM) fungi and nitrogen-fixing bacteria bear huge potential for sustainable agriculture by reducing the chemical fertilizer input required to maintain high crop yields. The regulation and signal transduction mechanism leading to AM and the nitrogen-fixing root nodule symbiosis (RNS) share common components including the calcium and calmodulin dependent protein kinase (CCaMK) and its phosphorylation target CYCLOPS, a DNA binding transcriptional activator (Tirichine et al., 2006; Yano et al., 2008; Singh et al., 2014). The CCaMK/CYCLOPS complex is a central regulatory hub in symbiosis signaling. It controls the expression of three transcriptional regulators of three distinct developmental programs. NIN controls nodule organogenesis and, together with ERN1, infection thread formation, while RAM1 is indispensable for arbuscule development (Singh et al., 2014; Pimprikar et al., 2016; Cerri et al., 2017). The corresponding promoters control distinct timing, expression domains and response to different stimuli.

The promoter choice and activity of CCaMK/CYCLOPS must therefore be coordinated at a spatio-temporal and a stimulus-specific level to trigger appropriate cell developmental programs. In the past, we identified additional putative complex components that may contribute to binding of diverse cis regulatory elements within the known target promoters of CCaMK/CYCLOPS. The doctoral candidate will study the relevance of the identified additional complex components using a range of techniques, including reverse genetics utilizing transposon insertion populations and/or CRISPR/CAS genome editing technology.

The spatio-temporal composition of the complex and its structural rearrangement will be studied via in vivo FRET-FLIM in root hair nuclei in response to signals emanating from arbuscular mycorrhiza fungi or nitrogen-fixing bacteria. Biochemical in vitro measurements will be used to quantify protein-protein and protein-DNA binding affinities. We expect to unravel key steps in the molecular dynamics of the CCaMK/CYCLOPS complex underlying the specific activation of the appropriate and distinct developmental programs in response to fungi and bacteria and thus the establishment of AM and root nodule symbioses.

2. Sequence adaptations in the symbiosis receptor-like kinase (SymRK) enabling nitrogen-fixing root nodule development

Plant root symbioses with arbuscular mycorrhiza (AM) fungi and nitrogen-fixing bacteria bear huge potential for sustainable agriculture by reducing the chemical fertilizer input required to maintain high crop yields. The regulation and signal transduction mechanism leading to AM and the nitrogen-fixing root nodule symbiosis (RNS) share a genetic toolkit largely conserved across land plants. It contains a set of signal transduction components including the Symbiosis Receptor-like Kinase SymRK. During evolution, SymRK appears to have acquired novel molecular features that facilitated the development of the nitrogen-fixing root nodule symbiosis, while maintaining its conserved function for AM.

In this project, we will explore sequence diversity among SymRK orthologs and paralogs with the goal to narrow down and identify critical sequence adaptations that underlie the rhizobial infection of plant cells. The doctoral student will investigate the mechanistic consequences of these adaptations at the cell biological and biochemical level with a focus on interacting proteins. The relevance of SYMRK paralogs and interacting proteins will be explored by reverse genetics utilizing transposon insertion populations or CRISPR/CAS genome editing technology and quantitative binding studies in vivo using advanced light microscopy and in vitro using a range of state-of-the-art technologies. We expect novel insights into the molecular mechanisms facilitating the symbiotic infection process of plant cells by nitrogen fixing bacteria.

3. Harnessing natural genetic resources to defend fruit plants against insect attack

Drosophila suzukii, a member of the vinegar fly family, has become the most damaging pest worldwide for a wide variety of soft fruits. While other Drosophila species lay their eggs into decaying fruits, D. suzukii has evolved the ability to insert eggs into the flesh of ready-to-harvest ripe fruits either on plants or in storage. Hatched larvae then consume the fruits from inside out and infected fruits are no longer suitable for human consumption. Aiming for a sustainable and effective control method, we utilized a diverse collection of strawberry plants (genus Fragaria) and identified sources of natural resistance to D. suzukii, the first-reported herbivore resistance in fruits.

Preliminary results indicate inhibitory effect at early stages of D. suzukii larvae development and involvement of plant secondary metabolites. As a consequence, resistant genotypes do not support proliferation of flies, hence limiting the source of infestation. In this project we aim to understand the genetic, molecular and metabolic mechanisms underpinning this resistant phenotype. We team up with strawberry breeding experts to approach the ultimate goal of transferring the resistance to commercial strawberry cultivars. In the long term we aim to identify the genes and mechanisms underlying this resistance and thus provide alternative strategies for the production of healthy fruits that can replace insecticide application.

Please note: 

You have to apply through our online application tool which is open until 30 November 2022, 12:00 noon CET!

For further information about the projects, feel free to contact the supervisor directly!

The research group of: Prof. Dr. Martin Parniske https://www.genetik.biologie.uni-muenchen.de/research/parniske/index.html

All available projects are detailed at www.lsm.bio.lmu.de/apply/pdh_projects/ where applicants can also find more information about the host groups.

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