Activator (Ac) from maize is a member of the hAT-superfamily of cut-and-paste transposable elements. For transposition, Ac requires only the transposase protein but no host factors. It is thus a convenient genetic tool for insertion mutagenesis and has been used for gene tagging not only in maize but also in various other plant species and yeast. However, transposition of Ac is, like that of many other transposons (Wang et al., 2016) modulated by environmental and cellular factors that are not fully understood and have limited the success of gene tagging experiments in some plant species. With the aim to improve Ac as a genetic tool, we (i) study its transposition mechanism and regulation using Arabidopsis thaliana and yeast (Saccharomyces cerevisiae) as experimental systems, (ii) develop hyperactive Ac transposase derivatives that catalyse higher transposition frequencies (Lazarow et al., 2012), and (iii) apply the Ac transposon for insertion mutagenesis in eukaryotic microorganisms.
The transposon team: Kevin Mielich, Julia Golz
Potassium (K) and nitrogen, mostly in the form of nitrate (NO3-) are essential macronutrients for all vascular plants. Potassium is involved in various cellular processes and essential for plant growth and development. Nitrate is the prevalent nitrogen source for most plants. Root-to-shoot translocation and shoot homeostasis of K+ determine nutrient balance, growth, and stress tolerance of vascular plants.
To maintain the cation-anion balance, xylem loading of K+ in the roots relies on the concomitant loading of counteranions like NO3-. Only recently, common components in the NO3- and K+ uptake pathways were identified, but it is unknown how their cross-talk on the molecular level is coordinated. One of these components is the bidirectional NO3- influx/efflux transporter NRT1.5, which is also involved in K+ homeostasis in shoots by affecting K+ root-to-shoot translocation in a NO3- dependent manner (Drechsler et al., 2015). In addition, NRT1.5 is involved in lateral root development under potassium deprivation (Zheng et al., 2016). We investigate the molecular functions of NRT1.5 and its interplay with other components of the nitrate and potassium homeostasis and metabolism.
The NRT1.5 team: Yue Zheng, Navina Drechsler, Florencia Sena, Melinda Kehribar
This research is a joint project of the R. Kunze and M. Hilker groups and part of the Collaborative Research Centre CRC973 "Priming and Memory of Organismic Responses to Stress".
When herbivorous insects deposit eggs on a leaf, the larvae that hatch some days later will start feeding on these leaves and damage the plant.
If plants can recognize egg deposits on their leaves, these can be reliable warning cues of subsequent larval herbivory and the plants get a chance to "prepare" for improved defence actions against the larvae. We found that egg deposition by the cabbage white butterfly (Pieris brassicae) onto Arabidopsis thaliana leaves, but not exposure of the plant to the other stresses like 'chilling' or fungal infection, improves the plant´s anti-herbivore defence against larvae (Firtzlaff et al., 2016). We investigate the characteristics of the egg-associated stimulus that warns Arabidopsis of future herbivory, the function of Arabidopsis genes with altered transcriptional profiles in feeding damaged leaves that previously carried eggs, the molecular 'memory' of the plants for prior egg deposition, and the impact of the plant´s longevity on its primability and persistence of the primed state.
The Priming team: Jana Oberländer, Malika Kebbi, Navina Drechsler, Clara Gottschalk