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Agaricus bisporus (Lange) Imbach is the most widely cultivated mushroom in Iran. Lack of diversity in mushroom crops, especially where disease is concerned, creates a crucial risk for the currently grown cultivars. The aim of this study was to assess the genetic diversity among Iranian wild strains and some commercial cultivars by using microsatellite markers. Eighteen codominant microsatellite markers of A. bisporus (AbSSR) were used to distinguish 17 wild and commercial strains. All of the microsatellite markers used in this research gave clear banding patterns, and only one strain remained undistinguished. Among 106 generated alleles, the wild subgroup presented 53 alleles never found both in brown and white commercial cultivars, and 42 alleles never found in commercial brown strains. The dendrogram obtained by UPGMA clustering analysis separated A. bisporus strains into six groups. Based on our results, the high level of genetic diversity among Iranian wild strains, compared with the commercial strains, provides a new and promising source of diversity for A. bisporus breeding programs. To our knowledge this is the first relevant study of biodiversity in native Iranian populations of A. bisporus.

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ContextThe fungal endophyte Serendipita indica enhances plant growth and plant resistance to biotic and abiotic stresses. Inoculum concentration greatly impacts the endophyte–plant interaction from mutualism to antagonism.Aims and methodsWe used both microscopy and qPCR to examine the effect of inoculum concentrations on the extent (%) and density of Brassica napus L. root colonisation by S. indica. B. napus seeds were inoculated with the fungus at five different inoculum concentrations (1–10% w/w basis).Key resultsStandard curves were constructed using the mean threshold cycle (Ct) and serially diluted gDNA ranging between 4.14×102 and 2.65×105 colony forming units (CFU). The result indicated a linear relationship between Ct and the log of input DNA. Variation in inoculum concentration significantly affected the root colonisation density by the fungus shown by qPCR. However, the percent root colonisation (PRC) measure was not affected and remained the same across all the treatments.ConclusionsOur findings show that the qPCR assay developed will determine the colonisation density whereas PRC gives a measure of the incidence of infected roots. Also, we suggest that the optimum quantity of inoculum is a key factor for a successful interaction that impacts the plant–S. indica interaction.ImplicationsTo our knowledge, this is the first study that quantitative qPCR has been used to investigate the correlation between inoculum quantities and the corresponding density of root colonisation in S. indica.

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