Breeding Lentinula Edodes Thermotolerant Strains By UV Mutagenesis

Lentinula edodes is saprophytic fungi produced in the northern hemisphere temperate to subtropical regions. It’s favorite by many people due to high nutrition value. China is a the largest L. edodes producer in the world. But the L. edodes production in China has been faced with a problem:The temperature in the main producing region of L. edodes is very high in summer, and L. edodes strains can fruiting in the high temperature is few. Reasons mentioned aboved lead to exceed supply of fresh lentinus edodes in summer.In order to solve the problem of insufficient supply of summer L. edodes, we should develop new strains that can fruiting in the high temperature enviroment. In this study, we chose the ability of recovering after treating at47℃as the screening indicator to selected thermotolerant strains after UV mutagenesis. After fruiting and analyzing the economical character, we evaluated thermotolerant strains with good-quantity and high-yield to apply to popularization and demonstration. We hope it can provide suitable varieties for L. edodes production in summer.This study includes three aspects:1.1. The first step is to obtain the thermotolerant strains by UV mutagenesis:1) We establish a new method of breeding L. edodes directly by UV mutagenesis. We select the protoplast as UV mutagenesis material. Then by establishing the preliminary screening indicators, optimizing the condition of protoplast preparation, chosing conditions of UV mutagenesis we determin the directional breeding method.2) Obtaining thermotolerant mutant strains. After mutagenesis, we screen24thermotolerant mutant strains of Hu Nong2, and screen57thermotolerant mutant strains of P18.2. In order to verificate the feasibility of the method used to select thermotolerant strains metioned above, we fruiting the mutants at25℃enviromen. After statistical analysis, we find that both Hu Nong2and P18have strains with heterobeltiosis when fruiting in the high temperarure enviroment. The result proved that the method of UV mutagenesis to obtain thermotolerant mutant strains directly is feasible.3. By analysis of the integrated traits of strains and we determine screening indicator. In order to reduce the work of breeding and build screening indicator, we use statistical methods to analysize the integrated traits of all strains. And then we obtain the thermotolerant strains with high yield and good fruit bodies,which can be apply to production. The analysis results showed:1) The growth rate of mutants has significant difference with parents in the alternating temperature process. And this difference is larger than that in the thermostatic process. Especially after undergoing the high temperature, mutant shows the obvious advantages. This resulut prove the advantage of mutant is the ability of high temperature tolarance.2) The growth rate in thermostat process, alternating temperature process, recover process has correlation with fruiting traits.The growth rate in the recover process is positively correlated with fruiting production, single mushroom traits, high temperature tolerance capability. So we chose it as the predictor of integrated traits of thermotolerant mutant strains.After analysis, we determine the screen indicator:Ignored strains with slow grouth rate under constant temperature. And then give up strains with slow grouth rate and fast grouth under high temperature. Using the growth rate in recovere process as the select indicator, we finally obtain strains with excellent traits as followed:N15, N24, N13, N14of Hu Nong2,and N24,N44of P18.