In vitro symbiotic seed germination and molecular characterization of associated endophytic fungi in a commercially important and endangered Indian orchid Vanda coerulea Griff. Ex Lindl.

Abstract

The technique of symbiotic seed germination-using fungi to cultivate orchid seedlings in vitro leading to their reintroduction in situhas considerable potential for conservation as evidenced by studies mostly in Australia and North America. However, its use has yet tobe fully realized throughout the world. On the Indian subcontinent, which harbors a considerable number of orchid species, symbioticgermination has been virtually unexplored. In the present studies, we provide a protocol for the symbiotic seed germination and ecorestorationof an endangered orchids Vanda coerulea Griff. ex Lindl., which is a floriculturally significant epiphyte used to progenatea vast variety of hybrids. Seeds were obtained from the mature un-dehisced capsules and sown on oat meal agar medium with thefungus isolated from the roots of mature V. coerulea plants in situ. Using molecular characterization techniques, cultures were assignableto Rhizoctonia zeae with teleomorph Thanatephorus cucumeris. All the seeds germinated within 5 wks of culture and very healthy,dark green protocorms were obtained in 5 month old cultures. Seedlings with 1–2 roots and 2–3 leaves were obtained in 8 months.These were acclimatized in the greenhouse for a year and introduced to their natural habitat at Manipur in North East India. Seedlinggrowth and development was continuously monitored, demonstrating active growth during monsoon season (April–July). Out of 29plants reintroduced, 23 survived and are growing well with the formation of new roots and leaves, observed after twelve months ofreintroduction.