Screening of a Lentinula edodes Mutant That Retains Lentinan Contents Long after Being Harvested Using TILLING

In the mushroom industry, there is a huge demand for methods for screening mutated strains in target genes without artificial gene manipulation. The TILLING method, which allows directed identification of mutations in a specific gene, was applied in Lentinula edodes. Strain Mu789, which has a mutation in the gene encoding beta-1,3-glucanase (exg2), was identified by TILLING. The beta-1,3-glucanase activity in Mu789 was suppressed by decreasing the amount of EXG2 compared with that in the parental strain, SR-1. The lentinan content, which is a beta-1,3-glucan in L. edodes with immunostimulation activity, was higher in Mu789 than in SR-1. Mu789 has 12 gene mutations with amino acid changes in the genome, theoretically suggesting one strain has a mutation in the target gene in almost 1000 mutants, indicating the success of the TILLING method in L. edodes. Our results will provide a basis for the application of the TILLING method in cultivating mushroom species.