1Department of Botany, DDU Gorakhpur University, Gorakhpur 273009.
2Sugarcane Research Station, Kunraghat, Gorakhpur-273008.
Abstracts of Research Papers Presented during the National Symposium of Indian Virological Society at Unit of Plant Virology, Division of Plant Pathology, Indian Agricultural Research Institute, New Delhi-110 012, October 14–1.
During local surveys in and around Gorakhpur (Eastern U.P., India), widespread occurrence of an apparently unrecorded mosaic disease on sorghum (Sorghum bicolor. cv. M.P. Cherry) was observed. The incidence ranged from 3 to 20%. The symptoms on naturally infected plants consisted of severe mosaic mottling and stunting of entire plant having few reduced ears. The dilution end point of the virus was between 10-3 to 10-4, thermal inactivation point 50°C and longevity in vitro 24 hours at room temperature (25±3°C). The virus was readily transmitted by sap and could not be transmitted through seeds of infected sorghum. The virus under study was transmitted through by Aphis gossypii, Longunquis sacchari, Myzus persicae and Rhopalosiphum maidis. The virus was systemic in graminaceous hosts only viz. sorghum cvs. M.P. Cherry, ICSV 705, 711, 145, IS 5619, PB 12874-1, OKY 48, SA 8735, Atlas, CSH-9, CSH-5, RIo, Q 7539, Nm-31, TX 2786, Trudex, Aums, Tamaran BTX-3197 and sudangrass (S. bicolor x S. sudanense). The symptoms on different sorghum cultivars varied from mild mosaic mottling, severe mosaic pattern, chlorotic streaks, tip necrosis resulting reduction of leaves, ears and entire plant. The virus also produced systemic mosaic infection on sugarcane. However, no symptoms were observed on other graminaceous hosts e.g. maize, johnson grass, Oryza sativa, Triticum aestivum, Ordeum vulgare, Pennisetum americanum and any member of the families leguminosae, cucurbitaceae, asteraceae, cruciferae and chenopodiaceae. Electron micrograph of leaf dip preparation revealed the presence of long flexuous thread like particles. The average size of the particles were 750 nm in length. In serological relationship tests, the virus gave positive reaction in DAC-ELISA with polyclonal antiserum of sugarcane mosaic virus. However, no reaction was observed with maize dwarf mosaic virus, johnsongrass mosaic virus, potato virus Y and sorghum mosaic virus (SCMV-H). This was further confirmed by uniform decoration of the virus particles in ISEM test with the antiserum of sugarcane mosaic virus. On the basis of host-range, physical properties, differential host reactions on different diagnostic sorghum cultivars, potyvirus like particles in electron microscopy and serological relationships, the virus isolate in the present investigation was identified as sugarcane mosaic virus (SCMV)-sorghum strain.
