| World mushroom production has become increasingly dominated by species that are both edible and have medicinal benefits and, in terms of output, Lentinula edodes ranks number one in this 'specialty' mushroom category. However, incorrectly designated strains result in huge economic losses for farmers, have a negative impact on mushroom breeding programmes, and restrict the overall development of the Lentinula industry. A SCAR primer pair (amplifying a band of 601 base pairs) was designed to identify one strain of L. edodes (strain 135). The accuracy of the marker in identifying '135' strains was then verified by using the SCAR primer pair to correctly amplify the single unique fragment from DNA samples taken from a total of 164 L. edodes strains representing ten '135' strains and 154 'non-135' strains.The purpose of this study was to determine the distribution patterns of the SCAR marker among different types of monokaryons, and to establish if there is stable inheritance of the marker in offspring generated by crosses between these monokaryons. The data will provide a scientific basis for the rapid identification of offspring strains, alleviate confusion in the naming of strains, and also aid breeding programmes.Maintained mycelium and tissue-isolated mycelium of L. edodes strain 135 were used to prepare protoplast monokaryons. Fifty-eight and 83 monokaryons were isolated from these sources, respectively and divided into two groups according to their phenotype, mating type and SCAR distribution patterns. The ratios of the two mating type monokaryons, A1B1 and A2B2, were 25:33 and 13:70, respectively. The outcome was a regular distribution pattern that demonstrated the stable inheritance of the SCAR marker and which is fundamental to the feasibility of marker-assisted breeding. In addition, fruit bodies grown under the same conditions but in two successive years (2005 and 2006) were used to prepare spore monokaryons. In this case, 154 and 294 spore monokaryons, respectively were isolated and their mating types determined. The relative proportion of the four mating types obtained in 2005 deviated markedly from the anticipated theoretical value. However, the observed proportionality was closer to the theoretical value among the 2006 samples, and recombined mating factors were discovered which increased the mating affinity during the breeding process. PCR amplification employing specific primers was used to establish the distribution of the '135' strain-specific SCAR marker among the spore monokaryons although no regular distribution of the marker relative to mating factors A and B was observed. Therefore, although the specific SCAR marker was inherited by all four L edodes mating types delineated in this study, it does not constitute an effective indicator of mating type among spore monokaryons.Finally, experiments in which SCAR-positive protoplast or spore monokaryons were crossed with SCAR-negative dikaryons or SCAR-negative monokaryons revealed that all the dikaryotic offspring carried the marker. However, the marker was absent from all the offspring generated from crosses between monokaryons of SCAR-negative 135 strains and monokaryons of other SCAR-negative strains. In conclusion, stable inheritance of the specific SCAR marker from monokaryons to dikaryotic offspring, and the feasibility of using the marker to identify offspring, have been demonstrated. Additionally, the marker can be used to confirm successful mating and to validate crossbreeding.
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