Distribution and serological diagnosis of sugarcane mosaic potyvirus in India.
During a survey of sugarcane crops in Uttar Pradesh, Tamil Nadu, Haryana, Maharashtra, Andhra Pradesh, Gujarat, Rajasthan, Punjab and Bihar, India, the incidence of sugarcane mosaic virus (SCMV) was reported in 81 varieties. The foliar symptoms varied in different cultivars and places but the most pronounced effects included contrasting shades of green and light green, often islands of normal green on a background of paler green or yellowish chlorotic areas on leaf lamina. The chlorotic areas were sharp and were generally accompanied by varying degrees of mosaic mottling with severe mosaic pattern with different chlorotic streaks, which extends to the full length of the leaf. The mosaic symptoms were most pronounced in the varieties in Tamil Nadu, Haryana and Maharashtra. Direct antigen-coated enzyme linked immunosorbent assay (DAC-ELISA) was standardized for the detection of virus in symptomatic suspected leaves. The DAC-ELISA screening of 101 mosaic samples showed that polyclonal antiserum of SCMV reacted strongly with 81 mosaic isolates. However, no serological relationship was detected with any of the other potyvirus antisera tested, viz. maize dwarf mosaic virus, sorghum mosaic virus and potato virus Y, in DAC-ELISA. Flexuous filamentous particles of 750+12 nm were found associated with the symptomatic leaves in leaf dip preparations. Based on the symptomatology, serological relationship and electron microscopy, the virus associated with the collected samples in nine states was identified as SCMV. The results also revealed that SCMV is widely distributed in all the surveyed states of India. The wide distribution of SCMV in India needs immediate attention to develop significant strategy to control and eliminate the virus from infected clones and to work on breeding for disease resistance against SCMV in India.