Arbuscular mycorrhiza on root-organ cultures

Abstract

The study of arbuscular mycorrhizal (AM) fungi and the AM symbiosis formed with host plant roots is complicated by the biotrophic and hypogeous nature of the mycobionts involved. To overcome this, several attempts have been made during the last three decades to obtain this symbiosis in vitro. The use of root-organ cultures has proved particularly successful. In this review, we describe the method by which root-organ cultures (transformed and nontransformed) have been obtained, together with the choice of host species, inoculation techniques, and culture media. We also outline the potential use of continuous cultures and cryopreservation of in vitro produced spores for long-term germ plasm storage. Furthermore, this review highlights the considerable impact that in vitro root-organ cultures have had on studies of AM fungal morphology, taxonomy, and phylogeny and how they have improved our understanding of the processes leading to root colonization and development of the extraradical mycelium. This is supported by a summary of some of the most important findings, regarding this symbiosis, that have been made at the physiological, biochemical, and molecular levels. We also summarize results from studies between AM fungi and certain pathogenic and nonpathogenic soil microorganisms. We describe some of the limitations of this in vitro system and propose diverse avenues of AM research that can now be undertaken, including the potential use of a similar system for ectomycorrhizal research.Key words: arbuscular mycorrhiza, root-organ cultures, Glomales, in vitro, root symbioses, source of inoculum, cryopreservation, intraradical and extraradical mycelium, mycorrhizosphere.

Arbuscular mycorrhizal and dark septate fungal associations in shallot (Allium cepa L. var. aggregatum) under conventional agriculture

“…COUGHLAN et al (2000) inferred that the tendency for colonization levels to increase with pH was due to the stimulation of the additional AMF taxa and/or a greater ability of the taxa present to colonize host roots. However, the positive influence of pH on AMF colonization contradicts the observations of WANG et al (2008) andFORTIN et al (2002) where increasing soil pH had detrimental effects on AMF spore germination and mycorrhization.…”

Coupling autotrophic in vitro plant cultivation system to scanning electron microscope to study plant-fungal interactions

“…The life cycle of Glomeromycota (Schüßler et al, 2001) has been described for several species (Fortin et al, 2002). The development of root organ culture (ROC) (see Declerck et al, 2005) improved significantly the description of the life cycle, among others for the vesicles-forming Glomus species (Chabot et al, 1992;Strullu et al, 1997).…”

Characterization of a CuZn superoxide dismutase gene in the arbuscular mycorrhizal fungus Glomus intraradices

“…The extraradical mycelium developing in the matrix soil is continuously exposed to variable environmental conditions and must quickly adapt to changing conditions. The development of AM in vitro cultures, that is the co-culture of transformed hairy roots and AM fungi, has allowed the investigation of soil-free extraradical hyphae and spores (Fortin et al 2002). By using this experimental system, it has been shown that environmental stresses, such as exposure to Cu or mechanical damage, promote ROS formation in the extraradical mycelium of Glomus intraradices (Fester and Hause 2005;Benabdellah et al 2009).…”