Naamdr. W Kohlen

OmschrijvingUniversitair docent
OrganisatieDepartement Plantenwetenschappen
OrganisatieeenheidLaboratorium voor Moleculaire biologie
Telefoon secretariaat+31 317 482 036
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BezoekadresDroevendaalsesteeg 1
PostadresPostbus 633
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Plants have the remarkable capability of continuously re-activating organogenesis throughout their life. Because of this, the full form of the plant body is not predefined during embryogenesis. This plasticity is achieved post-embryonically through the formation of new axes of growth: so-called secondary meristems. These meristems harbor plant stem cells, which are undifferentiated cells that provide a steady supply of organ precursor cells. As a plant physiologist I am mainly interested in the mechanisms controlling a plants ability to initiate such meristems, and what defines that some tissues are able to do this whereas other tissues cannot.

The main mechanism by which secondary meristems are initiated is through the activation of lateral organ founder cells. A key feature of this type of meristem initiation is that cells are set aside and retain a stem cell-like identity until they are activated later to form a new meristem. However, in some cases an even greater form of plasticity is achieved: so called de novo meristem initiation. In contrast to founder cell initiation, these meristems are initiated from fully differentiated cells. It has been postulated that these cells revert to an undifferentiated state in order to re-differentiate into a meristem.

Although shoot branching is crucial to determine the overall plant architecture in response to the environment, in agriculture this is often regarded as a problem. Much of a plant’s resources is invested in the formation of axillary buds and their outgrowth, thus reducing yield. However, complete removal of buds is also not desired, as this would create the risk of plant loss due to shoot apical meristem damaging. A combination of genetic removal of buds with the ability to induce de novo meristems when needed would be preferred. As such, understanding - and ultimately controlling – de novo axillary meristem formation would contribute considerably to the improvement of agricultural practice. Detailed knowledge on how axillary meristems are formed is therefore crucial. My research focusses on understanding how de novo meristem initiation in plants is accomplished. In a sense, to control de novo meristem initiation is to control plant architecture.




Comparative hormone profiling to underpin rhizobium symbiosis

In the legume-rhizobium symbiosis, formation of nitrogen-fixing root nodules is initiated upon perception of bacterial secreted lipo-chitooligosaccharides (LCOs). These so-called Nod-factors trigger the initiation of nodule primordia only in a specific zone of the root: the susceptible zone. The aim of my VENI project is to identify the hormonal landscape required for the creation of this susceptible zone.

Legumes evolved the rhizobium root nodule symbiosis ~60 million years ago (mya), followed by immediate massive evolutionary radiation. As a consequence the hormonal landscape of today’s species may display variation that cannot be causally linked to Nod factor permissiveness. To identify such I will define the hormonal landscape of the model legume Medicago truncatula. Next, I will investigate constraints on this hormonal landscape by comparing the hormonal landscape of Medicago truncatula to the hormonal landscape of carefully selected other legume species, including some that cannot form root nodules. Despite evolutionary divergence, I hypothesize the occurrence of conservation in hormonal balances is relevant for establishing the susceptible zone. By identifying such conserved modules, I aim to deduce a conceptual hormonal landscape essential for the creation of the root susceptible zone in legumes.

  • MOB-31812 - Toolbox Molecular Biology
  • MOB-70224 - MSc Internship Molecular Biology
  • MOB-70424 - MSc Internship Molecular Biology
  • MOB-79224 - MSc Research Practice Molecular Biology
  • MOB-79324 - MSc Research Practice Molecular Biology
  • MOB-80424 - MSc Thesis Molecular Biology
  • MOB-80436 - MSc Thesis Molecular Biology
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