Mapping of genomic regions (quantitative trait loci) controlling production and quality in industrial cultures of the edible basidiomycete Pleurotus ostreatus

Abstract

Industrial production of the edible basidiomycete Pleurotus ostreatus (oyster mushroom) is based on a solid fermentation process in which a limited number of selected strains are used. Optimization of industrial mushroom production depends on improving the culture process and breeding new strains with higher yields and productivities. Traditionally, fungal breeding has been carried out by an empirical trial and error process. In this study, we used a different approach by mapping quantitative trait loci (QTLs) controlling culture production and quality within the framework of the genetic linkage map of P. ostreatus. Ten production traits and four quality traits were studied and mapped. The production QTLs identified explain nearly one-half of the production variation. More interestingly, a single QTL mapping to the highly polymorphic chromosome VII appears to be involved in control of all the productivity traits studied. Quality QTLs appear to be scattered across the genome and to have less effect on the variation of the corresponding traits. Moreover, some of the new hybrid strains constructed in the course of our experiments had production or quality values higher than those of the parents or other commercial strains. This approach opens the possibility of marker-assisted selection and breeding of new industrial strains of this fungus.

FIG. 1.

Genetic linkage map of P. ostreatus (20), including the positions of QTLs and digenic interactions for production and quality traits. QTLs are placed at their approximate positions to the right of the markers. The percentages of the phenotypic variation explained by the putative QTLs (R²) are represented by proportional boxes. Significant interactions among QTLs, genes, and other molecular markers are indicated by arrows and numbers (see Table 5). Randomly amplified polymorphic DNA markers in the map are indicated by the primer name and the approximate length of the corresponding amplification product. Genes are in italics. Markers that deviated from the expected 1:1 segregation (P < 0.05) are indicated by an asterisk.