Study On Polyphasic Strain-typing Technique Of Lentinula Edodes

Lentinula edodes, as the best-known edible mushroom, was first cultivated in China more than 800 years ago. The production of China is the largest on the world these years. Although there are many commercial varieties of L.edodes, China has not enacted variety register to protect the breeder's right, and the methods of strain-typing undeveloped. The opinion about the genetic polymorphism of variety is controversial among reports.Strain-typing methods for L. edodes including antagonism, isozyme, intergenic spacer (IGS) and random amplified polymorphic DNA (RAPD), single one of them may not be ideal for variety register. To improve the discriminatory power (D) the present study combined multiple typing methods. Inter simple sequence repeats (ISSR) as a new typing method has not been applied in L.edodes. The objectives of the present study were to: 1) assess the application of ISSR in L. edodes; 2) evaluate the performance of the five methods for L. edodes typing-stain; 3) analyse the combining multiple typing methods; 4) estimate the genetic polymorphism of cultivated L. edodes strain in China.In the present investigation, 43 L.edodes strains including 41 cultivated strains cultivated on a large scale and 2 wild strains were collected from China. They were typed by the five methods of antagonism analysis, isozyme analysis, IGS analysis, RAPD analysis and ISSR analysis. The typing methods were evaluated with respect to discriminatory power (D), stability and reproducibility. The EST isozyme, RAPD, IGS1, SRI, IGS2 and ISSR analysis classified the 43 strains to 19 types (D=0.910), 20 types (D=0.932), 9 types (D=0.844), 10 types (D=0.697), 12 types (D=0.781) and 23 types (D=0.942) respectively. The ISSR analysis was most sensitive with discriminatory power. The reproducibility and stability were different for these methods, IGS1, IGS2 and SR1 analyses were highest; ISSR and EST analyses were higher; and RAPD analysis was lower.Combining the results of all these methods, we can discriminate 43 L.edodes strains into 29 types (D=0.967). However, the same discriminatory power (D=0.967) was observed with the combination of ISSR, EST and IGS2 analyses. Overall, the results indicated that no single method discriminate on strain level, the high discriminatory power was observed by combining several typing methods.The strains that belong to the same type were homogenous or identical in some aspects, while the strains among different types were heterogenous. There was great genetic diversity in the 29 types of China cultivated strains of L.edodes compared with the 2 wild strains.