A new approach for breeding low‐temperature‐resistant Volvariella volvacea strains: Genome shuffling in edible fungi

Volvariella volvacea is difficult to store fresh for lack of low-temperature resistance. Many traditional mutagenic strategies have been applied in order to select out strains resistant to low temperature, but few commercially efficient strains have been produced. In order to break through the bottleneck of traditional breeding and significantly improve low-temperature resistance of the edible fungus Volvariella volvacea, strains resistant to low temperature were constructed by genome shuffling. The optimum conditions of Volvariella. volvacea strain mutation, protoplast regeneration and fusion were determined. After protoplasts were treated with 1% (v/v) ethylmethylsulfonate (EMS), 40 s of ultraviolet irradiation (UV), 600 Gy electron beam implantation and 750 Gy60Co-γ irradiation, separately, the lethality was within 70–80%, which favored generating protoplasts being used in following forward mutation. Under these conditions, 16 strains of Volvariella. volvacea mutated by ethylmethylsulfonate, electron beam, ultraviolet irradiation and 60Co-γ irradiation were obtained. The 16 mutated protoplasts were selected to serve as the shuffling pool based on their excellent low-temperature resistance. After four rounds of genome shuffling and low-temperature resistance testing, three strains (VF1, VF2 and VF3) with high genetic stability were screened. VF1, VF2 and VF3 significantly enhanced fruit body shelf life to 20, 28 and 28 h at 10°C, respectively, which exceeded 25, 75 and 75% respectively compared with the storage time of V23, the most low-temperature resistant strain. Genome shuffling greatly improved the low-temperature resistance of Volvariella. volvacea, and shortened the course of screening required to generate desirable strains. To our knowledge, this is the first paper to apply genome shuffling to breeding new varieties of mushroom, and offers a new approach for breeding edible fungi with optimized phenotype. This article is protected by copyright. All rights reserved