Use of ISSR markers for strain identification in the button mushroom, Agaricus bisporus.

The white button mushroom Agaricus bisporus is the most widely cultivated specious of edible mushrooms all over the world. Originating from a limited heritage line, commercial strains of A. bisporus are supposed to be genetically very similar. Many highly polymorphic molecular markers have been exploiting for strain identification in wild and commercial strains of this mushroom. ISSR marker with the whole-genome coverage, accuracy and reproducibility as well as robustness has proved to be a promising marker for genetic diversity analysis of many crops. The objective of this work was to evaluate the potential of ISSR markers for genotype identification in common button mushroom, A.bisporus. For this purpose, 18 A.bisporus genotypes, including four cultivars, 13 hybrid strains and their single spore progenies along with an indigenous wild strain, were assessed for their similarity using 20 ISSR primers. Out of 20 primers, 10 proved to be discriminative in A.bisporus, producing 110 scorable and 76 polymorphic bands. The similarity degree was calculated for each couple of genotypes according to the Jaccard coefficient and grouping was carried out by the UPGMA clustering analysis. ISSR primers successfully identified every single individual; however, high similarity was detected among genotypes. As we expected, the wild genotype Dezful exhibited little relatedness with other genotypes and placed in a separate individual group. Genotypes IM0037 and Dezful with similarity coefficient of 0.44 and genotypes 737 and IM00Ca12 with similarity coefficient of 0.937, were accordingly the least and the most similar genotypes. Our result demonstrates that ISSR markers are powerful enough for detection of polymorphism among closely related genotypes of A. bisporus.