Phylogeography of the ectomycorrhizal Pisolithus species as inferred from nuclear ribosomal DNA ITS sequences

Abstract

Summary• The fungal genus Pisolithus is cosmopolitan in warm temperate regions and forms ectomycorrhizal associations with a wide range of woody plants. To delimit phylogenetic Pisolithus species and identify their geographical distribution, 102 collections were made worldwide and their rDNA internal transcribed spacer (ITS) was sequenced.• Phylogenetic analyses of these sequences, together with 46 additional GenBank accessions, identified 11 species.• A strong phylogeographical pattern was observed related to the native geographical origin of the host plants. In the Holarctic, P. tinctorius was widely distributed, associated with Pinus and Quercus . It has been co-introduced with pines to other biogeographical regions. Several Pisolithus lineages, including P. aurantioscabrosus , occurred in restricted biogeographical regions associated with endemic plants, such as Afzelia in eastern Africa. Pisolithus albus , P. marmoratus and P. microcarpus were associated with Australasian hosts ( Eucalyptus , Acacia ) and were distributed with their hosts worldwide. By contrast, two additional unnamed species were restricted to Australia.• The present study shows that evolutionary lineages within Pisolithus are related to the biogeographical origin of the hosts. In addition, regional floras and endemic plants could act as hosts of endemic species of Pisolithus .

Morphological and molecular characterization of Pisolithus in soil under eucalyptus plantations in Brazil

“…The structures were similar to the phylogenetic cladogram in Martin et al (2002). The sequences of all isolates used in this study were distributed in clades 1 and 2, with strong bootstrap support (99 %) (Figure 2).…”

“…One group included the isolates VIC 30593, VIC 30598, VIC 30599, VIC 30602, VIC 30604, and VIC 30606, together with PT90A and RS26, also from Brazil (Figure 2, Tables 1 and 2), and was identified as Pisolithus microcarpus (Martin et al, 2002). The other group that included MU98/2 and MU98/12, was identified as Pisolithus albus, native to Australia (Martin et al, 2002) (Table 2, Figure 2). …”

“…The first species included isolates VIC 30596, VIC 30597 and VIC 30600 that grouped with MU98/5A and MU98/9, identified as Pisolithus marmoratus, isolated from Eucalyptus globulus in a forest of Australia (Martin et al, 2002). The second species group was the hypogeneous Pisolithus called P. hypogaeus.…”

“…Australian eucalypts was introduced into Southeast Asia, India, Africa, South America, South Africa, and southern Europe in the last 200 year in form of seeds and saplings, which facilitated the dispersal of Australian Pisolithus (Martin et al, 2002).…”

“…Based on RFLP analysis of the ITS sequences of several Pisolithus isolates, Farmer & Sylvia (1998) suggested that this taxon represents a complex species. At least 11 different clades have been reported, of which the major were recognized as phylogenetic species (Martin et al, 2002).…”