Pisolithus is an important ectomycorrhizal genus world-wide, however to date we remain largely ignorant of the genetic and functional variation that exists within isolates of this genus. Fifty-three isolates of Pisolithus were obtained from various locations in central and eastern Australia and genetic variation within the isolates was assessed using ITS-RFLP and ITS sequencing analyses. RFLP analysis initially grouped the isolates into eight RFLP types. Neighbour-joining analysis of ITS sequences with Pisolithus ITS sequences available in databases clustered the majority of isolates into four groups within two major clades, each comprising isolates of similar basidiospre characteristics. Most Australian isolates correspond with recent provisional descriptions of P. albus or P. marmoratus. One isolate (LJ30) had low sequence identity (61.6-78.0%) to the other isolates and probably represents a separate undescribed Australian species. Significant intraspecific variation was observed in ITS-RFLP profiles for the putative P. albus isolates, suggesting that the sole use of RFLP analysis in diversity assessment may over-estimate Pisolithus species richness. Investigations were also initiated to identify if a relationship exists between genetic and physiological diversity in Australian Pisolithus. It is, however, clear that extensive physiological variation exists in Australian Pisolithus isolates. The size and distribution of genets of Australian Pisolithus species I and II ( putative P. albus and P. marmoratus) was also assessed using microsatellite-primed PCR to gain a better understanding of the likely distribution of underground mycelial networks and possible reproduction strategies in native soils. The data demonstrate that both species have the ability to be long-lived and extend for significant distances in native soils in undisturbed conditions. The field site for Pisolithus species I, however, also contained of a large number of small individuals suggesting that this species may employ a life-history strategy combining r-, C and S characteristics depending on local soil conditions / Doctor of Philosophy (PhD)

Pisolithus is an important ectomycorrhizal genus world-wide, however to date we remain largely ignorant of the genetic and functional variation that exists within isolates of this genus. Fifty-three isolates of Pisolithus were obtained from various locations in central and eastern Australia and genetic variation within the isolates was assessed using ITS-RFLP and ITS sequencing analyses. RFLP analysis initially grouped the isolates into eight RFLP types. Neighbour-joining analysis of ITS sequences with Pisolithus ITS sequences available in databases clustered the majority of isolates into four groups within two major clades, each comprising isolates of similar basidiospre characteristics. Most Australian isolates correspond with recent provisional descriptions of P. albus or P. marmoratus. One isolate (LJ30) had low sequence identity (61.6-78.0%) to the other isolates and probably represents a separate undescribed Australian species. Significant intraspecific variation was observed in ITS-RFLP profiles for the putative P. albus isolates, suggesting that the sole use of RFLP analysis in diversity assessment may over-estimate Pisolithus species richness. Investigations were also initiated to identify if a relationship exists between genetic and physiological diversity in Australian Pisolithus. It is, however, clear that extensive physiological variation exists in Australian Pisolithus isolates. The size and distribution of genets of Australian Pisolithus species I and II ( putative P. albus and P. marmoratus) was also assessed using microsatellite-primed PCR to gain a better understanding of the likely distribution of underground mycelial networks and possible reproduction strategies in native soils. The data demonstrate that both species have the ability to be long-lived and extend for significant distances in native soils in undisturbed conditions. The field site for Pisolithus species I, however, also contained of a large number of small individuals suggesting that this species may employ a life-history strategy combining r-, C and S characteristics depending on local soil conditions / Doctor of Philosophy (PhD)