*Corresponding author. E-mail: Sandra.Urbanelli@ uniroma1.it Biological Journal of the Linnean Society, 2002, 75, 125–136. With 3 figures Mushrooms of the genus Pleurotus are well known as decomposers of a wide range of agricultural wastes, and for their ability to produce fruitbodies with excel- lent organoleptic qualities. Research with a view to obtaining strains of high nutritional value, optimising cultivation techniques, and selecting the most suit- able substrates continues, all of which requires the use of clearly identified biological material. There is, therefore, a need to describe and evaluate the varia- tions which will allow researchers to discriminate among taxonomic units within the genus. In order to clarify the taxonomic status of the enti- ties it is important both to study the reproductive isolation between them and to find appropriate descriptors that can recognize them, including mor- phological features, molecular markers and ecological parameters. Reproductive isolation is usually assessed in fungal species by considering intersterility between groups. Mating criteria, easily detectable in sapro- phytic fungi, are widely employed in the studies for species circumscription (Vilgalys, 1991). The mating tests in basidiomycetes revealed that intersterility barriers between most species are nearly always absolute, but partial intersterility is known to occur (Chase & Ullrich, 1990). Intersterility barriers are studied through laboratory experiments, but these are not sufficient to evaluate the reproductive isolation between taxa in the case of partial intersterility. Many taxa can be artificially induced to cross and produce viable and fertile offspring in the laboratory, while they may rarely or never mate in the field, even under sympatric conditions, on account of efficient isolation mechanisms (ecological, temporal, etc.) other than sterility (Mayr, 1970; Dobzhansky, 1970). Hence it is © 2002 The Linnean Society of London, Biological Journal of the Linnean Society, 2002, 75, 125–136 125 Molecular genetic analysis of two taxa of the Pleurotus eryngii complex: P. eryngii (DC.Fr.) Quèl. var. eryngii and P. eryngii (DC.Fr.) Quèl. var. ferulae S. URBANELLI 1 *, C. FANELLI 2 , A. A. FABBRI 2 , V. DELLA ROSA 1 , L. MADDAU 3 , F. MARRAS 3 AND M. REVERBERI 2 1 Department of Genetics and Molecular Biology, University ‘La Sapienza’ of Rome, Via dei Sardi 70,00181, Rome Italy 2 Department of Plant Biology, University ‘La Sapienza’ of Rome, Via dei Sardi 70,00181, Rome Italy 3 Department of Plant Protection, University of Sassari, Sassari, Sardinia Received 23 May 2001; accepted for publication 28 October 2001 With the use of isozymes and PCR-fingerprinting analysis molecular markers were found between the varieties Pleurotus eryngii var. eryngii and P. eryngii var. ferulae within the Pleurotus eryngii complex, which allowed the identification of the fruitbodies collected in Southern and Central Italy. The study of sympatric localities has shown that there is no gene exchange between them in the field. The post-mating barriers between these taxa are not yet completely efficient. However, in the field the gene pools of the two taxa appear isolated and associated with spe- cific host plants: Eryngium campestre and Ferula communis. On the basis of the genetic and ecological differences observed and given the absence of gene exchange in sympatric localities, P. eryngii and P. ferulae are to be consid- ered distinct biological species. © 2002 The Linnean Society of London, Biological Journal of the Linnean Society, 2002, 75, 125–136. ADDITIONAL KEYWORDS: host specificity – isozyme analysis – molecular taxonomy – Pleurotus – PCR finger printing analysis – reproductive isolation. Downloaded from https://academic.oup.com/biolinnean/article-abstract/75/1/125/2638795 by guest on 01 June 2020