Morpho-anatomical characterization of Rhizopogon himalayensis - Cedrus deodara mycorrhiza

Abstract

Rhizopogon himalayensis (Castellano, S.L. Miller, Singh & Lakhanpal) A.B. Mujic & M.E. Sm., comb. nov. -an edible truffle-like fungus- normally exists in a symbiotic association with Cedrus deodara (Roxb.) Loud. Because of this important association and the ecological significance as per the available literature attached to this fungus, the present study was undertaken with a specific objective to test the mycorrhizal viability of this mycobiont with this important tree species of Himalaya -the theme tree of Himachal Pradesh. An attempt to investigate and record morphological and anatomical characteristics and variations in this mycorrhizal association was also made in nursery conditions using pure culture (wheat grain spawn) of R. himalayensis. The seedlings grown and inoculated in the nursery were harvested after six months for further examination, including the microscopic details. The study and subsequent analysis revealed that that mycobiont had invaded most of the feeder roots, imparting a typical swollen appearance to the mycorrhizal root tips. These root tips were light ochre with moderately thick plectenchymatic fungal mantle with occasional clamp connections on the inner layer of the fungal mantle. The root surface, as seen, was found smooth and frequently covered with a loose aggregation of inter-woven hyphae that uniformly pervaded the epidermis extending into the inter-cortical spaces of outer cortical cells and formed a characteristic Hartig net. Thus, results obtained in fact for the first time, presented an in-depth analysis of the morphological and anatomical characteristics of R. himalayensis and C. deodara association.

Ectomycorrhizas of Rhizopogon himalayensis on Cedrus deodara

“…Thereafter several studies have observed EcM association with this tree species [21,[61][62][63][64][65][66][67][68][69][70][71][72][73]. Moreover, many researchers have successfully synthesized Rhizopogon ectomycorrhizae with several conifer species under laboratory conditions [25,[74][75][76][77][78][79][80][81][82][83], beside this, the seedlings of C. deodara have been inoculated with pure cultures of several EcM fungi other than Rhizopogon sp [84][85][86][87]. However, there have been relatively very few studies confirming in vitro synthesis between R. himalayensis and C. deodara seedlings [25,83] and needs more research to characterize this association with the roots C. deodara growing in pure forests.…”

“…The microscopic characters like peridium, hymenal tissue, tramal tissues, basidia, basidioles, sterigmata, and basidiospores were recorded using Nikon eclipse E-400 microscope. The species was identified by following available literature [25,[29][30][31]46] and authenticated by DNA sequencing.…”

“…In context to the ectomycorrhizae of C. deodara [43], were the first to investigate morpho‐anatomical features of the mycorrhizal roots of C. deodara . Later on Singh [29] and Thakur et al [25]. described the changes in root phenology and above ground growth characteristics of C. deodara inoculated with R. himalayensis , as well as anatomically confirmed the EcM association under in vitro conditions.…”

“…Rhizopogon Fr. is a member of the family Rhizopogonaceae, which produce hypogeous or semi-hypogeous basidiomes and establish EcM associations with members of the Pinaceae family [22][23][24][25]. Through a comprehensive phylogenetic analysis of the nuclear recombinant DNA (rDNA) internal transcribed spacer (ITS1-5.8S-ITS2) region, Rhizopogon has been categorized into five distinct subgenera: Rhizopogon, Roseoli, Versicolor, Amylopogon, and Villosuli [26,27].…”

Tell me who your neighbors are: The role of spatial location and tree species identity in determining the ectomycorrhizal community composition of saplings and mature trees in a mixed conifer forest

“…Little is known of the EMF communities of Cedrus deodara , especially out of its native range, but preliminary assessment of its EMF community in the Himalayas (Pande et al, 2004) showed association with various taxa such as: Boletus , Russula and Amanita . Other studies demonstrated a potential association with Rhizopogon (Thakur et al, 2021) and Scleroderma (Itoo and Reshi, 2014) under nursery conditions. The rooting systems of the mature Pinus halepensis and Cedrus deodara differ greatly.…”