Characterization of 18 Novel Polymorphic SSR Markers and Evaluation of Genetic D

1School of Life Science, Anhui Agricultural University, Hefei, Anhui 230036, China; 2Key Laboratory

of Microbial Resources Collection and Preservation, Ministry of Agriculture, Institute of Agricultural

Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing 100081, China;

3Beijing Academy of Science and Technology, Beijing 100089, China

Oyster mushrooms represent one of the most important groups of commercially cultivated edible mushrooms worldwide. In this study, 18 novel polymorphic simple sequence repeat (SSR) markers were developed and characterized from Pleurotus ostreatus, strain ACCC 50838. The number of alleles detected for each SSR locus varied between three and twelve across the 52 oyster mushroom cultivars, 48 of which were previously designated as P. ostreatus and four as P. pulmonarius. The polymorphism information content (PIC) of the SSRs ranged from 0.34 to 0.84. All 52 cultivars were differentiated using the 18 SSR markers except for two small groups, comprised of three and two strains respectively, which were also indistinguishable on the basis of ISSR profiles, somatic compatibility patterns and agronomic traits such as temperature type and pileus color. Similarity matching (SM) coefcients for all the SSR bands ranged between 0.755 to 0.9995, and a dendrogram based on these values separated the 52 cultivars into two distinct groups (P. ostreatus and P. pulmonarius) at the similarity level of 0.79. A high degree of heterogeneity among the Chinese cultivars was revealed by the SSR markers, which have considerable potential for evaluating genetic diversity essential to future oyster mushroom breeding programs.

Simple sequence repeat (SSR); oyster mushroom; Pleurotus ostreatus; Pleurotus pulmonarius; genetic diversity; strain differentiation

The oyster mushroom is one of the most popular edible mushrooms in many countries of the world. According to statistics provided by the China Edible Fungus Association, oyster mushroom production in China in 2010 reached four million tons fresh weight. Annual yields are among the highest among all the different edible mushrooms cultivated in China.

When modern-day farming of oyster mushrooms began, wild strains were adopted for cultivation without genetic improvement. Since then, considerable effort has been made to breed improved strains using controlled crosses and selection of offspring. Good genetic resources are essential material for breeding and, after strains were collected from the wild and identified, their genetic make-up and agronomic traits were determined in order to select the best parents for crossbreeding.