2.9.7
ROOT ENDOPHYTES IN MEDICINAL PLANTS: THEIR POPULATION AND EFFECTS

M BASU1 and NK SRIVASTAVA2

lBotany Department, Allahabad University, Allahabad 211002, India; 2Botany Department, SDJPG College, Chandeshwar, Azamgarh, India

Background and objectives
Root endophytes comprising of a group of fungi, constitute the most striking example of mutualistic symbiosis inside the root tissues of the host plants, formed by aseptate fungi are the vesicular-arbuscular mycorrhiza, found in 90% of the plants [1]. VA mycorrhizal fungi - nearly invisible colonizers of most of the plant root systems - have been tested as growth and quality enhancers. Medicinal plants are now receiving much attention all over the world for their natural healing powers. They are the Nature's chemical industry for the production of vital medicinal compounds.|

A few attempts have demonstrated the association of VAM fungi with medicinal plants but the effects of VAM fungi on the medicinal values received little attention. Hence, the present study was undertaken to evaluate the occurrence of VAM endophytes in certain medicinal plants to record the infection, spore population and their effects on growth and medicinal values.

Results and conclusions
Fifty-five medicinal plants, collected from four districts of Uttar Pradesh, India, belonging to 28 families of flowering plants, were screened for mycorrhizal association. Except for two plants, all were found to be mycorrhizal. The spores were observed in all the samples, even in the rhizosphere soil of nonmycorrhizal plants. In all four locations the infection at flowering and fruiting stages was highest, ranging up to 95%. The maximum infection and spore population were recorded in the families Papilionaceae, Fabaceae and Euphorbiaceae, while lowest were in Cactaceae and Typhaceae. Thirteen different species of mycorrhizal spores, belonging to three genera, Glomus (seven species), Gigaspora (four species) and Scutellospora (two species), were obtained from the rhizosphere soil collected from four locations, Glomus mosseae and G. ;fasciculatum were selected from the 13 species tested as test organisms for single and mixed inocula, for exploring the efficacy of VAM fungi in enhancing growth and the medicinal values of five medicinal plants, Allium sativum, Corriandum sativum, Occimum basilicum (essential oil); Sesamum indicum (essential oil and vitamin) and Trigonelia foenum-graceum (alkaloid). The plants are important because of their medicinal compounds. The important plant parts being leaves and seeds.

It was observed that mixed inocula was better enhancer of growth and root-shoot biomass for all the test plants. It also markedly enhanced essential oil and alkoloid contents. However, very slight improvement in vitamin content was observed. Strikingly there was no change in essential oil content in case of C. ;sativum when VAM fungi were supplemented either singly or in mixed inocula.

It is well known that variations exists in the effectiveness of VAM endophytes in stimulating plant growth. It is difficult to find all the essential qualities required for being the most efficient species in a single VAM endophyte and hence a mixed inocula provided an effective form of inoculum [2].

Results suggest that mycorrhization enhances growth and improves productivity of medicinal compounds. Hence, the application of VAM endophytes are beneficial for overall improvement of valuable medicinal plants.

References
1. Kendrick WB, Berch SM, 1985. Comprehensive Biotechnology 3, 109-52.
2. Daft MJ, Hogarth BG, 1983. Transactions of the British Mycolcological Society 80, 339-45.