dr. MJW (Marieke) Jeuken

dr. MJW (Marieke) Jeuken

Onderzoeker

I am a plant scientist and most stimulated by the discipline of genetics, which relates from segregation of traits in populations to discovery of gene sequences in DNA. When I studied Biology at the University of Utrecht, I focused on genetics and did my MSc thesis work at the labs of Sjef Smeekens, Sjeng Horbach and Norman Terry (UC Berkeley).

My PhD graduation at the chair group Plant Breeding at WUR was under the supervision of Piet Stam and Pim Lindhout and concerned the exploration for resistance genes of a wild lettuce species (Lactuca saligna) against the devastating downy mildew disease in lettuce cultivation.

My current research focus lies on the genetics behind biotic stress resistance and reproductive barriers between crops and their crop wild relatives. In my model crop, lettuce (Lactuca sativa), I study the origin and mechanisms of biotic stress resistance and the nearly complete reproductive isolation between a domesticated (L. sativa) and a related wild species (L. saligna).

Within the discipline of biotic stress resistance, resistance in nonhost species is arguably the most interesting but least understood type of resistance. The wild species, L. saligna, is completely resistant to all downy mildew isolates and therefore is it a nonhost species. As a rule, related host and non-host plant species are too much diverged from each other and are not crossable or their F1 is completely sterile. Exceptionally L. saligna is crossable with L. sativa  and the F1-hybrid is slightly fertile (2% seed set). These interspecific progenies offer a unique opportunity to study the resistance at the genetic level. The final aim is to unravel the genetic network of  this complete resistance against downy mildew and to introgress the resistant gene-variants in lettuce cultivars.

Furthermore, I use the same interspecific cross to study the adverse effects of this interspecific hybridisation. Plant hybrid incompatibilities, like hybrid inviability and sterility, in F1 or derived progenies allow me to elucidate components of evolutionary diversification, speciation and reproductive barriers between these species.

Both phenomena, reproductive isolation and resistance of nonhost species, are genetically complex traits. A good understanding of the causes and consequences of these complex traits is essential for further application in plant breeding.