Identification and strain-typing of button mushroom using ISSR, ITS and IGS markers

The button mushroom commercial strains are supposed to be genetically very similar because they have originated from a limited heritage lines. Identification and strain-typing of this mushroom could solve issues of breeding and recording legal ownership. Molecular markers and sequencing of specific regions in the genome have provided appropriate tools for evaluating genetic diversity and relationship. ISSR marker has proved to be a promising marker for identification of close genotypes. On the other hand, sequences of ITS and IGS regions of ribosomal DNA in fungi are unique areas that offer useful evolution information. The objective of this work was to evaluate the potential of molecular tools for genotype identification in the button mushroom. For this purpose, 23 genotypes of three species of button mushroom were assessed for their similarity using 20 ISSR primers. ITS and IGS regions of ribosomal DNA also were amplified by specific primers and sequencing were done. Out of 20 ISSR primers, 13 proved to be discriminative in button mushroom, producing 245 scorable and 242 polymorphic bands. According to the similarity matrix, the lowest polymorphic coefficient (0.92 and 0.95) belonged to the primers 841 and 809, respectively and the highest (1.0) belonged to the other primers. Genotypes P4 and Dezful with similarity coefficient of 0.100 and genotypes yousefi and 512 with similarity coefficient of 0.961, were accordingly the least and the most similar genotypes. Data aggregation from primers No. 808, 809, 841 and 842 showed that these four primers are able to isolate all the genotypes with close relationship. On the other hand, sequencing results of ITS and IGS regions indicated that these areas are identical between genotypes of one species but are different between species. Therefore they are able to discriminate the button mushroom species. Our result demonstrated that ISSR markers compared with ITS and IGS regions are powerful enough for detection of polymorphism among closely related genotypes of button mushroom and can be used for fingerprinting and legal ownership.