Molecular methods for research on arbuscular mycorrhizal fungi in India: problems and prospects

Research on arbuscular mycorrhizal fungi (AMF), presently, is at the crossroads. Some aspects like their beneficial role in overall plant growth under diverse edaphic conditions, have been thoroughly investigated and further, there is no second opinion to the advocacy of their development as bioinoculants. However, the biosystematics, culturability and field performance evaluation of this group of fungi are still some areas lagging behind for want of suitable techniques, which have become hurdles for further progress of research. Having exhausted all the options to resolve the issues, the mycorrhizologists are looking towards molecular aspects of this group of organisms. rDNA region of the genome, with its variable and conserved regions, has been found to be an ideal location to offer solution to the issues. PCR-based techniques have become mandatory to obtain sufficient quantities of DNA, as these organisms are nonculturable and thus only a small quantity of DNA could be isolated from spores and infected roots. Employing DNA-based molecular markers, some advancements and success have already been achieved in areas like phylogeny, taxonomy and functional symbiosis. The next one or two decades are going to witness tremendous increases in molecular level research on this group of organisms, which hopefully will help resolve many issues being confronted today. This article reviews the molecular investigations carried out during the last two decades all over the world and also project areas for future research in India.