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Title: Studies on Diversity and Physiological Characterization of Morels of the Western Himalayan Region
Authors: Kanwal, Harpreet Kaur
Supervisor: Reddy, M. S.
Keywords: Morel, Morchella, Mushroom, molecular diversity, Western Himalayan region, Phylogenetic analyses, ligninolytic enzyme, lignin degradation, lignocellulosic substrates, sclerotia, cultivation
Issue Date: 28-Dec-2011
Abstract: The Himalayan region in India is known for its great biodiversity. The Himalayan morel (Morchella) popularly known as “Guchhi” is an economically important, edible and the most desirable wild mushroom, which belongs to ascomycetes. Morels have been important to mankind since a long time but yet humans could not get hold of them till date. Even though, it has been an exciting field for research, still the taxonomy of morels is poorly known. In the present study, an attempt has been made to study the diversity and taxonomic position of Morchella isolates occurring in the western Himalayan region of India. The classical and molecular diversity of thirty-two different Morchella cultures/fruiting bodies, collected from the Western Himalayan region was studied. Phylogenetic analyses based on DNA sequences could help in sorting out morel taxonomy which is essential to better define the morel diversity. In this study, sequence analyses revealed that in the Western Himalayan region of India, both yellow (M. crassipes, M. spongiola) and black morels (M. elata, M. angusticeps, and M. gigas) were prominent along with two Verpa species. Phylogenetic analyses by maximum parsimony, maximum likelihood and Bayesian inference revealed two different clades and a clear distinction between yellow and black morels. The physiology of different Morchella spp. too had been studied in different nutritional and environmental conditions. Morchella spp. exhibited different growth patterns to different nutritional and environmental conditions. Malt extract, mineral salts broth and potato dextrose broth served as the best media for the growth of Morchella spp. Carbon sources such as glucose, fructose, mannose and cellobiose were utilized well by all the Morchella spp. Organic nitrogen sources (casein, tryptone, peptone and yeast extract) were found to be good sources for growth rather than inorganic nitrogen sources. Optimum range of temperature for the growth of Morchella spp. was found to be from 20 - 30 °C and pH range was between 8.5 and 9.5. Laccase activity increased in the presence of mannose, rhamnose, galactose, ribose, sorbose and mannitol. Morchella crassipes (MR8 and MR5) produced highest laccase activity using mannose as the carbon source. Organic sources increased the laccase production as compared to the inorganic ones with peptone and casein being the best. Maximum laccase activity was observed in peptone followed by casein in M. crassipes (MR8). This study, also, evaluates the ligninolytic enzyme activities and lignin degradation on different lignocellulosic substrates that can be utilized further for the fructification in morels. Rice straw, groundnut shell, wheat straw, pine needles, ABTS and veratrylalcohol appeared to be the best for laccase production. Maximum laccase activity and lignin degradation was observed in M. crassipes (MR8 and MR5) in rice straw and ABTS as the substrates. Sclerotial studies of these Morchella spp. with different media, carbon and nitrogen sources also concluded the variations among these species. Carbon sources, such as ribose, cellobiose, galactose, glucose, xylose, sucrose and mannitol served the best carbon sources for sclerotia formation. Yeast extract and NaNO3 promoted the formation of small coloured sclerotia. Different substrates such as wheat straw, rice straw, apple leaves, groundnuts shell, eucalyptus leaves, bamboo leaves, orange peels, pine needles, wheat bran, wheat grains, and carrot peels supported the growth. Morchella spp. were found to produce ligninolytic enzymes during their growth on different substrates. Substrates such as wheat grains, wheat bran and wheat straw served the best substrates for ligninolytic enzyme production. Also examined the role of ligninolytic enzymes during the phase of sclerotia formation and maturation in morels so as to get an insight in understanding the cultivation aspects in morels. Large number of sclerotia was formed on combination of soil and substrate (wheat starw and wheat grains) along with the ligninolytic enzyme activities during the course of sclerotia formation and maturation in M. crassipes (MR8). The present work also deals with involvement of laccase enzyme by M. crassipes mycelium during sclerotia formation on agricultural substrates. So this type of study can be helpful in exploring the fungal biodiversity of India and for selecting the suitable isolates for cultivation purposes. The use of these sources for enhanced ligninolytic enzyme production plays an important role in improving the cultivation aspects in morels.
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