An integrated study of individualism in Lentinula edodes in nature and itsimplication for cultivation strategy

A field study was carried out in a remote broadleaved Fagus longipetiolata forest in Shaanxi province, China to study the natural local distribution o f Lentinula edodes. Following spatial mapping, 24 fruit bodies were collect ed for tissue isolation into axenic culture. 24 genets distributed on falle n tree trunks within a distance of 120 m were identified and clustered into 7 groups using the unweighted pair-group method algorithm using data based on colony morphologies, abilities to degrade aromatic poly-R478 dye, somat ic incompatibility reaction patterns and DNA fingerprints. Among the parame ters used, the somatic incompatibility reaction, a polygenic phenotype, was the most differentiating, identifying 22 incompatible classes. Two sets of fruit bodies of different genets were so close together that they would ot herwise have been described as aggregate fruits of presumed identical origi n. Eighteen genets found on the same 5.6 m long tree trunk divided roughly into two clusters, matching their spatial distribution, and a nearby branch bore another distinct cluster. More heterogeneity was encountered between isolates the greater the distance separating them on the original site. Gen ets on the same tree trunk showed more compatible somatic reactions among t hemselves, and their DNA fingerprints showed higher similarity. Nevertheles s, considering the totality of phenotypic characters, each fruit body is a genet in L. edodes. Such features are concluded to result from a reproducti ve strategy which depends on basidiospore dispersal. Within each cluster of isolates from the collection site genets seemed to have arisen from multip le sib-mating events. Thus, a cluster may represent a lineage of L. edodes. Individualism in L. edodes is based on a strong somatic incompatibility sy stem. Strong competition from contaminating individuals arriving as air-bor ne basidiospores could explain decreased and fluctuating crop yields which are now frequently observed in later flushes from the outdoor wood log cult ivation system. Further, it would also explain why multispore spawn is not favoured in artificial cultivation of this economically important edible mu shroom.