Molecular Ecology of the Rhizosphere

research group Prof. Dr. Joost T. van Dongen

Plant development

ROS-dependent growth regulation in plants

Project leader: Jos Schippers  PhD student: Alicja Kunkowska

We study genetic regulatory networks that control leaf size in both the model plant species Arabidopsis thaliana and selected crop species. Final leaf size is remarkably constant under controlled environmental conditions, indicating that leaf growth is controlled by genetic factors. Leaf development encompasses 3 defined phases (Figure 1).




The first involves the establishment of the leaf primordia through selective proliferation of a group of cells at the shoot apical meristem. Once sufficient cells have been produced, cell proliferation ceases and the final size of the leaf is determined by their expansion. Based on transcriptome data covering the leaf development gradient, putative growth-regulating transcription factors have been selected for functional analysis. For this we use molecular-genetic, genomic and biochemical approaches in combination with high resolution phenotyping, bioinformatics and modeling of biological processes. Special emphasis within this project is given to the role of reactive oxygen species (ROS) and the circadian clock in regulating leaf development.

In addition to the regulation of plant development under stable conditions we focus on the adaptation of the growth response in a changing environment. One of the initial responses of any organism to stress is the adjustment of growth. Especially the increased occurrence of weather extremes is a major factor influencing crop production and yield.


Molecular control of ageing and the onset of leaf senescence

Project leader: Jos Schippers 

Senescence constitutes the final phase of leaf development and represents an important process that determines yield and reproductive success. Senescence is typically manifested by the development of spectacular autumn leaf colors. In addition, senescence is closely linked to issues that impact on food security such as maximizing yield, optimizing grain filling, and the reduction in postharvest losses. The plant hormone ethylene is the principal hormone implicated in the regulation of senescence processes. However, ethylene only results in the execution of senescence once the leaf has reached a certain developmental age.


The objective of the study here is to understand the molecular mechanisms that allow for the onset of leaf senescence by ethylene in Arabidopsis, but also monocot species. The phytohormone ethylene is especially important to the field of postharvest biology, to prevent food spoils. Next to that, it is an important key to control ripening processes in a diverse number of crop species.

ROS-signaling pathways and post-translational control of protein activity

Project leader: Jos Schippers  PhD student: Alicja Kunkowska

When plants are exposed to unfavorable conditions, they rapidly respond to adjust their metabolism and development. Perturbations of cellular processes mostly cause a change in reactive oxygen species (ROS) homeostasis. Unrestrained accumulation of ROS result in oxidative damage of plant tissues and ultimately to cell death. However, ROS are far more than just damaging molecules. Nowadays they are recognized as universal signaling molecules, which guide plant responses and can modulate protein properties in a reversible manner – more soon –