Mushrooms

Mushroom research

Our research is directed on understanding the genetics of edible mushrooms in order to improve breeding efficiency. The focus is on button mushrooms (Agaricus bisporus) and oyster mushrooms (Pleurotus ostreatus). For this we also explore the biological variation within our large collection of varieties (>5000 strains representing 125 species) by assessing genetic relatedness within species and quantifying several phenotypic characteristics.

We also explore the utilisation of fungi for selective degradation of lignin in organic (waste) materials.  Research done so far has shown that a number of species degrade substantial portions of lignin while hardly consuming cellulose. These fungi can thus be used to make cellulose bioavailable in low value organic waste, upgrading it into animal feed or feedstock for the production of bioenergy.

Biodiversity

Plant Breeding has a large collection of fungi that produce edible mushrooms (the collection contains 5000 strains representing more than 125 species). The focus is on button mushrooms (Agaricus bisporus), oyster mushrooms (Pleurotus spp.) and shiitake (Lentinula edodes).

Phenotyping edible mushrooms

Unifarm has an experimental climate controlled growing facility for small scale production of edible mushrooms. The design allows cultivation comparable to commercial production, and reliable phenotyping (a.o. resistance to diseases, quality, yield, etc.). The rooms are also designed for contained cultivation of genetically modified strains.

Substrate utilisation by button mushrooms

Substrate (compost) is one of the main cost factors in button mushroom production. Research is directed to unravel the way vegetative mycelium is degrading organic matter and how this is used for the formation of mushrooms. This knowledge is used to improve the efficiency of the cultivation system. In addition, the biological variation in the collection is used to improve the substrate utilisation by commercial varieties.

Breeding: mapping traits in segregating populations

The mushroom Research Group generates segregating populations for traits relevant for the primary producers (yield, quality, disease resistance) or consumers (taste, bioactive compounds, etc.). Linkage maps are generated using SNP markers or GBS (genotyping by sequencing). Markers linked to traits are subsequently used for selection in offspring. An example of a breeding product of the group is a sporeless oyster mushroom.

Button mushroom as a model for studying meiosis

Button mushroom is represented by two compatible subspecies differing in the interchromosomal crossovers. In commercial lines and most wild isolates, crossovers are mainly restricted to chromosome ends whereas in the other subspecies crossovers take place over the entire chromosome. Segregating populations are used now to study mechanisms behind these two recombination landscapes. This might generate knowledge to control meiosis either to enhance or retain allele combinations.

Almost all button mushroom cultivars used worldwide are very similar. Want to know why? Read the article Why are all button mushroom cultivars similar?

Mushrooms and bio-based economy

The utilisation of lignocellulose is limited by the presence of recalcitrant lignin. Physical and chemical pretreatments are now used to reduce/modify lignin and enhancing the access to (hemi)cellulose. White rot fungi (including many edible fungi) selectively degrade lignin during vegetative growth and can thus be used to valorise lignocellulose in a low tech, low cost and sustainable way.

Research is directed to:

  • Screening optimal fungal-organic matter combinations
  • Optimize conditions for selectively degrading lignin
  • Using biological diversity within each fungal species to optimize lignin degradation (including breeding)

Genetic regulation of mushroom formation

Genes that are differentially expressed in vegetative growth and initiation of mushrooms (pins) are overexpressed or knocked-out using Atum transformation (via cross-over and CRISPR-Cas9). The aim is to unravelling the mechanism of mushroom formation which allows a better control of a mushroom crop and might lead to the commercial production of until now non-cultivable mushroom species.

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