In vitro synthesis of ectomycorrhizas on Casuarinaceae with a range of mycorrhizal fungi

Abstract

SUMMARYEleven species of mycorrhizal fungi, selected from stands of either Eucalyptus spp., Allocasuarina spp, or Pinus radiata D, Don were tested in an aseptic system for their abilities to initiate ectomycorrbiza with Allocasuarina littoratis (Salisb,) The comparative intensity of ectomycorrhizal infection by P. tinctorius and L. laecata was assessed on four host species. Infection intensity ranged from 13 to 70'V, of laterals infected and decreased for both fungal species in the order: A. littoralis > Eucalyptus pilularis Smith > C. equisetifolia > C. cunninghamiana.An exogenous supply of glucose induced greater and sometimes earlier, ectomycorrhizal infection of A. littoralis, C. equisetifolia and C. cunninghamiana by P. tinctorms and /.., laecata tban tbat in the absence of giucose. Tbe optimum glucose level for tbese fungi and bosts in tbis synthesis system was 750/^g glucose (g soil)"'.

Frankia Nodulation, Mycorrhization and Interactions Between Frankia and Mycorrhizal Fungi in Casuarina Plants

“…Arbuscular mycorrhizal (AM) colonization ranges from 10 to 70% while EM ranges from 10 to 50% in Casuarina plants (Gardner 1986;Theodorou and Reddell 1991;Vasanthakrishna and Bagyaraj 1993;Subba-Rao and Rodriguez-Barrueco, 1995;Vasanthakrishna et al 1995;Singh et al 1998;He et al 2004He et al , 2005. The effectiveness and AM colonization through various AM species are consistent with different Casuarina species.…”

“…For example, two isolates of Pisolithus (H4111) and Scleroderm (H4314) could only induce a very low (1.7-2.3%) root colonization in 3-month-old C. equisetifolia roots (Dell et al 1994). In the same experiment, another isolate of Sources : Rose 1980;Gardner1986;Theodorou and Reddell 1991;Vasanthakrishna and Bagyaraj 1993;Vasanthakrishna et al 1995 Pisolithus (H4458) was unable to form EMs and the Scleroderm (H4151) isolate has even resulted in the death of C. equisetifolia seedlings (Dell et al 1994). In contrast, Duponnois et al (2003) recently found that Pisolithus and Scleroderina isolates did form EMs on C. glauca under axenic conditions, but without the appearance of the typical Hartig net.…”

“…In addition to Frankia symbiosis, Casuarina plants can form another symbiotic association with either AM or EM fungi (Rose 1980;Gardner 1986;Sidhu et al 1990;Cervantes and Rodriguez-Barrueco 1992;Theodorou and Reddell 1991;Khan 1993;Subba-Rao and Rodriguez-Barrueco 1995;Smith and Read 1997). A variety of AM or EM fungal species is given in Table 2.…”

“…A variety of AM or EM fungal species is given in Table 2. In general, either AM or EM could contribute to a successful Frankia symbiosis in Casuarina plants by increasing N 2 -fixation especially in P-deficient soils, by enhancing uptake of P, other mineral nutrients and water from the soil, and by having a generally protective role against environmental stresses, such as in arid climates (Gardner 1986;Theodorou and Reddell 1991;Subba-Rao and Rodriguez-Barrueco 1995;Smith and Read 1997). An important physiological and ecological distinction between AM and EM is that AM develops more extensively in mineral soils whereas EM flourishes in highly organic surface soils (Smith and Read 1997).…”

“…In addition, Casuarina root systems can associate with either arbuscular mycorrhizal (AM) fungi, ectomycorrhizal (EM) fungi or both to form mycorrhiza (Warcup 1980;Gauthier et al 1983;Gardner 1986;Reddell et al 1986;Theodorou and Reddell 1991;Vasanthakrishna and Bagyaraj 1993;Vasanthakrishna et al 1994aVasanthakrishna et al , 1994bVasanthakrishna et al , 1995Subba-Rao and Rodriguez-Barrueco 1995;Reddell et al 1997;Osundina 1998;Singh et al 1998;Mark et al 1999;Wang and Qiu 2006), which helps their host plants to access soil nutrients and water. Some Casuarina species, including C. cunninghamiana, C. equisetifolia and C. glauca, even have the capacity to form cluster roots, which specialize in phosphorus (P) uptake from the soil (Diem 1996;Arahou and Diem 1997;Reddell et al 1997;Diem et al 2000;Zaïd et al 2003;Lambers et al 2006).…”