P-12. First Record of Association of Badana virus with Finger millet (Eleusine coracana (L.) Gaertn.) Mosaic in India

Finger millet (Eleusine coracana (L.) Gaertn.), commonly known as birds foot, Nagli, Mandua and ragi in different parts of India is one of the important millet crops in tribal belts. It is an indispensable to Indian Agriculture as a source of grain and straw in vast dry land areas. This nutritious millet is highly nutritious and even superior to rice and wheat in certain constituents. Seeds are richest source of protein (7.3 g), crude fibre (3.6 g), mineral matter (2.7g), fat (1.3 g), carbohydrates (72g), calcium (344 mg), phosphorus (283 mg), and iron (3.9 mg) per 100 grain. The grains have high dietary fibre and helps in prevention of constipation, lowering of blood cholesterol and slow release of glucose to the blood streams during digestion. Never the less, lower incidence of cardiovascular disease, duodenal ulcer and hyperglycemia (diabetes) are reported among regular millet consumers. In India, finger millet has been grown over an area of 2.15 million hectares with an average production of 2.68 million tones (Anon., 2003). Infected leaf samples of finger millet were collected from Coastal Andhra Pradesh. About 2.0 mm of infected leaf tissue were cut from symptomatic leaf and ground in phosphate buffer (0.07 M, pH-6.5). 10ml of the extract was placed on parafilm in a moist Petri plate and carbon coated copper grids (400 mesh) were placed over it. The grids were then washed with distilled water and stained with 2% freshly prepared aqueous uranyl acetate, (pH-4.5). Excess of stain was immediately removed by Whatman's filter paper. The grids were examined under JEOL, JEM-1011 transmission electron microscope (TEM) and digital images were recorded by Gatan DV 300 W CCD camera attached to EM. Immuno sorbent electron microscopy (ISEM) was performed as described by Milne and Lesemann (1984). Antisera of following badnaviruses were used in ISEM tests: banana streak virus (BSV), sugarcane bacilliform virus (ScBV), Kalanchoe top-spotting virus (KTSV), Piper yellow mottle virus (PYMV), Dioscorea bacilliform virus (DBV), cacao swollen shoot virus (CSSV), and Commelina yellow mottle virus (CoYMV) and rice tungro bacilliform virus (RTBV). Antibodies of all these badna viruses were received from Prof. B.E.L. Lokhart, Department of Plant Pathology, University of Minnesota, St. Paul, MN 55108 and antibodies of RTBV was available at Plant Virology Unit, Division of Plant Pathology, Indian Agricultural Research Institute, New Delhi. Electron microscopy of negatively stained samples from leaves of naturally infected E. coracana showed typical bacilliform virions measuring 100–130 x 30 nm. A virus concentration was very low in leaf tissue and only one particle was observed in one EM field. Approximately 4–5 particles were observed in one square of EM grid. However, in trapping with antisera of sugarcane bacilliform virus the concentration was slightly increased. In decoration test a clear antibody halo was observed around the particle. Virions were also observed in clumps showing strong reaction of decoration. In decoration test all the antisera of badnaviruses viz: banana streak virus (BSV), sugarcane bacilliform virus (ScBV), Kalanchoe top-spotting virus (KTSV), Dioscorea bacilliform virus (DBV), cacao swollen shoot virus (CSSV), and Commelina yellow mottle virus (CoYMV) reacted with positively finger millet bacilliform virus. However no reaction was observed with rice tungro bacilliform virus (RTBV). Badna virus has been reported in India from banana (Ann. 1995), citrus (Ahlawat et al., 1996), sugarcane (Vishwanathan et al., 1996) and black pepper (Bhat et al., 2003). Majority of the badna viruses are reported from vegetatively propagated plants and association of badna virus from finger millet is a new report. The particle morphology and its serological reaction in ISEM with range of badna viruses indicate that the virus belongs to genus badna virus. This is the first report of badna virus infection in finger millet.