Ectomycorrhizal biology of Shorea robusta roots in association with Russula Pers. (Russulaceae; Basidiomycota) from foothills of Himalayas, India

Abstract

In this paper the morphoanatomical details of mycorrhizal roots of Shorea robusta associated with three Russula species viz. Russula chlorinosma Burl., Russula azurea Bres. and Russula cyanoxantha (Schaff.) Fr. were investigated for the first time. The EcM roots of S. robusta are much shorter than non-mycorrhizal roots and are variously branched. The EcM colonized roots are distinguished by differences in the shape and color of mycorrhizal system, surface texture, size and shape of cystidia, cell shape of mantle, as well as the differing chemical reactions. Mycorrhizal roots of Russula chlorinosma are mainly characterized by irregularly pinnate to simple mycorrhizal system, stringy to cottony, white to grayish brown surface, while Russula azurea have irregularly pinnate to coralloid, smooth, purple to grayish purple mycorrhizal system, whereas it is mostly simple, to monopodial pinnate with loosely short-spiny and light brown surface in case of Russula cyanoxantha. Size of cystidial elements are much larger in mycorrhizal roots of Russula cyanoxantha (52-114 × 3.0-6.5 µm) as compared to Russula chlorinosma (16-50 × 3-5 µm) and R. azurea (16-40 × 3-5 µm). In Russula chlorinosma cystidia are sub-cylindrical to obclavate and clavate to flask-shaped with acute to rounded apex and it was awl-shaped in Russula cyanoxantha with almost acute apex and swollen or bean shaped base, whereas it is sub-cylindrical to clavate with rounded apex, often similar to the ends of normal hyphae in R.  azurea.