On site discrimination between two closely related commercial strains of oyster mushroom using a loop-mediated isothermal amplification (LAMP) test

Background: Protection of the intellectual property (IP) rights on new crop varieties is important as it allows the breeding company or entity that produced the variety to earn back (part of) the investment. Infringement on the IP rights of mushroom varieties is not uncommon. In order to combat infringement of the IP rights on two strains of Oyster mushroom (SPOPPO and ALLERPO) it is important to be able to readily recognize and discriminate the two strains in commercial practice. This article describes the development of tools for the on-site identification of two closely related sporeless strains of Oyster mushroom. Methods and results: To develop a reliable method of discriminating between SPOPPO and ALLERPO, we used either the LAMP technique or a modification of that technique. It allows for fast (within 30 min) identification of the commercially used strains SPOPPO and ALLERPO with high specificity. Fast on-site answers on strain identity can be important when experiencing unexpected strain behavior or when strains are of suspect origin. Both strains are discriminated from sporulating strains by a LAMP reaction on the intact version of the msh4 gene; sporeless strains contain a msh4 gene with a large insert that renders the associated protein inactive. Conclusions: SPOPPO and ALLERPO are distinguished from each other and other commercially used Pleurotus ostreatus strains by LAMP reactions that target genomic regions with strain specific recombinations. To our knowledge, this is the first time LAMP reactions have been developed to discriminate between Pleurotus ostreatus strains.