|Title||Genetic base of self/non-self recognition in button mushrooms (Champignon)|
|Group||Plant Breeding, Laboratory of|
|Supervisor(s)||Anton Sonnenberg, Karin Scholtmeijer & Fons Debets|
|Examiner(s)||Anton Sonnenberg & Fons Debets|
|Description||Description: Mycelia of filamentous fungi are capable of anastomosis (fusion between mycelia) when growing on an organic substrate and will thus form a network. This network is used to transport nutrient to growing areas (usually the edge of a colony) or to growing mushrooms. This anastomosis will only take place between mycelia that are vegetative compatible, i.e. have identical incompatibility (het) loci. If the interacting individuals are genetically dissimilar at some or all of their het loci, usually cell death of the interacting hyphae will occur. The vic loci have not been identified yet in button mushrooms (Agaricus bisporus). Compost producers have occasionally inoculated their compost with two varieties and in many cases colonization was bad with low mushroom production indicating that vegetative incompatibility also exists for button mushrooms. Knowledge of the genes involved gives breeders the opportunity to breed different button mushroom varieties that can be use in one crop, similar to grafting used in plants (under and upper stem in apples, for example). Button mushrooms are cultivated in a two layer system: the lower layer consists of the nutrition rich compost and the top layer of nutrition poor peat. The latter is needed to trigger the mycelium to form fruiting bodies. Usually only the compost is inoculated with a pure culture of the button mushroom and the fungus is subsequently colonizing the top layer of peat. Only the mycelium in the top layer will produce mushrooms whereas the mycelium in the compost is feeding these growing mushrooms. That allows the inoculation of the compost and peat layer with different varieties that will anastomose when they are vegetative compatible. That offers the option of generating varieties that have an optimal substrate utilisation and other varieties that produce high quality mushrooms. These varieties can be made vegetative compatible by breeding also for identical vegetative compatibility genes. For this, the number and location of these genes must be mapped. The first experiments done to study interaction between compatible and non-compatible varieties indicate the existence of vegetative incompatibility for the button mushroom mycelium but reactions were not always very clear. The aim of this thesis is to zoom in on the interaction between compatible and incompatible varieties using strains with differentially labelled nuclei and start with mapping chromosomes harbouring vic genes using chromosome substitution lines.
Work to be carried out:
� A number of varieties will be genetically modified in such a way that nuclei have different fluorescent colours.
� A number of varieties (identical and non-identical) will be confronted on thin agar layers. Contact zone will be examined microscopically to see what the fate is of nuclei in the contact zone. This will help to understand what a �compatible� and a �non-compatible� reactions is.
� Confront varieties on natural substrate, i.e. compost, to evaluate the phenotype in compatible and incompatible mating
� Confront a series of lines in which in each line almost a complete chromosome has been substituted with a non-substituted line. This may elucidate what chromosomes harbour one or more vic genes.
|Requirements||One or several of these courses: Gene-technology, Genetic Analysis Tools and Concepts, Population and Quantitative Genetics, Genomics|