Arbeitsgruppe Jun. Prof. Steven Jansen Ph.D.

Research topics

• Comparative anatomy of the vascular tissue in tropical plants: how are xylem anatomical characters influenced by phylogeny and adaptation to environmental stresses?
• The structure and function of pits and pit membranes in xylem
• Aluminium accumulation in tropical plants

Current research projects

• “The relationship between microscopic hydraulic networks and water transport in plants” (Ministry for Science, Research, and Science, Baden-Wurttemberg, Germany, Juniorprofessorenprogramm)
• Xylem Functional Traits” (Australian Research Council – New Zealand Research Network for Vegetation Function Working Group)
• “The physiology and anatomy of drought resistance in conifers” (Royal Society International Joint Project)

Outline summary of present research

My research focuses on the evolution and structure-functional relationships of xylem tissue in plants. Although in many cases xylem anatomical diversity patterns reflect phylogenetic relationships, there is a considerable amount of homoplasy, which can partly be interpreted to be the result of ecological adaptations for water transport and mechanical support. Ecological trends in turn can be understood as functional adaptations when considering trade-offs between structure and function in different growth forms and environments, especially with respect to conductive efficiency, vulnerability to cavitation (embolism), and mechanical strength.

Special attention is paid to structure-functional aspects of pits and pit membranes in water conductive cells in order to examine (1) how minute pores in pit membranes can regulate water flow between neighbouring tracheary elements, and (2) to what extent efficiency vs. safety trade-offs apply to pit structure. My anatomical work includes electron microscopy, atomic force microscopy, and X-ray computed tomography.

Trade-offs in hydraulic function are influenced by both pit level differences in structure and by tissue level changes in conduit allometry (average length, diameter) and the three dimensional network of xylem cells. I aim to quantify the 3 D structure of xylem cell types and how differences in the arrangement of connections between tracheary elements and parenchyma cells may influence xylem function.

In addition, aluminium accumulation is studied in tropical plants in order to understand the systematic and ecological distribution of this trait and which factors control the uptake, movement and detoxification of Al in aboveground plant tissues.