DETECTION OF SUGARCANE STREAK MOSAIC VIRUS IN SUGARCANE FROM SEVERAL ASIAN COUNTRIES

摘要

Five sugarcane leaf samples exhibiting mosaic symptoms and that originated from Bangladesh, India, Sri Lanka, Thailand, and Vietnam reacted negatively in RT-PCR assays with Sugarcane mosaic virus (SCMV), Sorghum mosaic virus (SrMV) and potyvirus specific primers. Mosaic symptoms were reproduced after mechanical inoculation of sugarcane, maize and sorghum plants with diseased leaf extracts, but symptoms were not as severe as those caused by SCMV and SrMV. Electron microscopy of partially purified virions from inoculated plants showed flexuous filaments characteristic of the Potyviridae family. The five sugarcane leaf samples reacted, however, in RT-PCR assays with two primer pairs designed to detect Sugarcane streak mosaic virus (SCSMV), the causal agent of sugarcane streak mosaic, an unclassified member of the Potyviridae family. SCSMV was detected by RT-PCR in 34 leaf samples from 30 cultivars exhibiting mosaic symptoms and that originated from Bangladesh, India, Pakistan, Sri Lanka, Thailand, and Vietnam. The amplicon (0.5 kb) from the coat protein coding region of five virus isolates showed 97% to 99% identity with SCSMV from Pakistan (GenBank accession number U75456) and 93 to 95% with SCSMV-AP from India (GenBank accession number Y17738). Our results suggest that: I) SCSMV is the major cause of mosaic symptoms in sugarcane in several Asian countries; ii) streak mosaic is widespread in Asia; and iii) the disease is caused by at least two different strains of SCSMV in India. Additionally, sugarcane leaves exhibiting mosaic symptoms can be simultaneously infected by SCSMV and SCMV.