Selectivity in the Lichen Symbiosis

Photobiont association and genetic diversity of the optionally lichenized fungus Schizoxylon albescens

“…Although in vitro studies focusing on the initial stages of the lichenization process have shown that axenically isolated lichen mycobionts and photobionts can reform lichenized structures in culture (Ahmadjian et al, 1980;Ahmadjian & Jacobs, 1981;Bubrick et al, 1985;Ott, 1987;Galun & Garty, 1988;Stocker-Wörgötter, 1995, 2001Schaper & Ott, 2003), we did not observe any penetration peg or haustorium -a typical structure of lichenization in which fungal hyphae enter the photobiont cells to extract nutrients (Honegger & Brunner, 1981;Tschermak-Woess, 1988;Honegger, 1991Honegger, , 1993) -in our culture experiments. Only fungal hyphae adhering tightly to the algal cells were observed.…”

First report on polysaccharides of Asterochloris and their potential role in the lichen symbiosis

“…Regarding lichen symbiosis, the surface of the photobiont may be important in the interaction between lichen symbionts, since lectins produced by the mycobiont and located at the fungal cell wall were found to bind to specific ligands at the algal cell wall [20,21]. An interesting experiment demonstrating the importance of the surface of the photobiont in the interaction between lichen symbionts, was reported by Ahmadjian and Jacobs [22].…”

Compatibility and thigmotropism in the lichen symbiosis: A reappraisal

“…This paper focuses on the early development of stratified thalli that contain trebouxioid photobionts. The sequence of events leading to a stratified thallus can be summarized in four basic stages: stage one, pre-contact, which is prior to physical contact of symbionts but close enough that extracellular interactions are possible; stage two, early-contact, where fungal cells contact algal cells by appressoria and/or subsequently envelop them through an increase in short lateral branches; stage three, incorporation of growing fungal and algal units into an undifferentiated mass; and stage four, differentiation of layered tissues (Ahmadjian et a1., 1978;Bubrick et al, 1985;Galun, 1988). The molecular mechanisms behind this sequence of events are unknown.…”

“…investigating the compatibility and selectivity of symbionts towards their partners (Ahmadjian et al, 1980;Ahmadjian and Jacobs, 1981;Bubrick et al, 1985;Galun and Garty, 1988;Kon et al, 1993;Ott, 1987;Schaper and Ott, 2003).…”

“…Nearly 100 years later, similar experiments reinvestigated the thigmotropic response using either Cladonia cristatella or Xanthoria parietina and algal sized glass beads (Ahmadj ian and Jacobs, 1981; Bubrick et al, 1985). Members of both Cladonia and Xanthoria form lichen thalli with trebouxioid algae and show a stage 2 specific response (Galun, 1988).…”