Studies on mycorrhizal compatibility and in vitro propagation of some commercially important andor endangered Indian orchids

Abstract

Five species of commercially significant and/or endangered Indian orchids (Arundina graminifolia, Goodyera repens, Herminium lanceum, Oreorchis foliosa var. indica, and Rhynchostylis retusa) were studied with a view to assessing their mycorrhizal compatibility and in vitro propagation [seed germination (symbiotic and asymbiotic) and regeneration potential]. In the present study, the isolated fungal endophytes were characterized using both morphological and molecular techniques [Arundina graminifolia (AG1: Fusarium sp. and AG2: Trichoderma sp.); Goodyera repens (GR1: Linnemannia elongata); Herminium lanceum (HL1: Ceratobasidium sp. and HL2: Fusarium sp.); Oreorchis foliosa var. indica (Oreo1: Tulasnella sp.); and Rhynchostylis retusa (RR1: Ceratobasidium sp. and RR2: Fusarium sp.]. Only six isolates were able to induce onset of seed germination; subsequent protocorm development was, however, observed only in HL1 and RR1 (fungal isolates) inoculated symbiotic seed cultures. newlineThe asymbioytic germination percentage of micro-seeds varied from species to species; it was, however, highest in case of Arundina graminifolia (81.97±0.38%; MS) followed by Goodyera repens (79.57±0.47%; VW), Rhynchostylis retusa (75.77±1.20%; M), and Herminium lanceum (63.75±0.71%; M). Presently, incorporation of IAA in KC medium proved optimal for protocorm development in Arundina graminifolia, whereas supplementation of IBA in M medium proved the best for stimulating early emergence of leaf primordia in Rhynchostylis retusa. The acclimatized seedlings/plantlets when transferred to ex vitro conditions were regularly sprayed with nutrient solutions and exhibited varied survival percentage [Arundina graminifolia (75%), Goodyera repens (55%), Herminium lanceum (60%), and Rhynchostylis retusa (80%)]. newline newline