Not Available

Not AvailableMosaic caused by sugarcane mosaic virus (SCMV), a Potyvirus is widespread and affecting cane production in India. Recently occurrence of another virus, sugarcane streak mosaic virus (SCSMV), a Tritimovirus in plants showing mosaic has also been reported in the country. Further studies were conducted to identify associated viruses with mosaic with a set of sugarcane varieties by RT-PCR using virus-specific primers. Among the nine major varieties exhibiting different types of symptoms tested, four varieties viz, BO 72, Co 740, CoC 671 and CoPant 84213 were found to have infections of both SCMV and SCSMV. Whereas, the varieties viz., Co 89003 and CoS 94270 were positive to SCMV only and CoJ 77, CoJ 86 and CoM 9217 were positive to SCSMV alone. In RT-PCR, a product of ~900 bp and 870 bp were amplified for SCMV and SCSMV, respectively. The amplicons from sugarcane varieties viz., BO 72, Co 740 and CoC 671 for SCMV and Co 740, CoC 671 and CoJ 77 for SCSMV were cloned, sequenced and were compared with the database sequences. Four of our SCMV isolates showed 96.80 to 99.30% nucleotide identity among them and are closer to the Australian isolates than any other continental isolates. When compared to SCMV, relation of the new SCSMV isolates with the database sequences is comparatively low. Among the four isolates, 84.80 to 96.70% nucleotide sequence identity was observed. The SCSMV-CB671 sequence was closer to the SCSMV-PAK strain and the rest of the three sequences were closer to the SCSMV-AP strain. The phylogenetic analyses of 36 SCMV sequences reported from different continents were grouped according to their continental origin under five major groups. The tree constructed with maximum likelihood method with molecular clock showed that the other SCMV isolates lineated from SCMV CB isolates. The phylogenetic analyses of 13 SCSMV sequences were distributed in three major groups. One of our four SCSMV nucleotide sequences SCSMV-CB671 grouped with SCSMV-PAK and the remaining three formed another separate subgroup, grouped with SCSMV-AP. The results established for the first time that sugarcane mosaic is the cause of SCMV and SCSMV either alone or in combination. The nucleic acid sequences coding for viral coat proteins exhibit less variation in SCMV and wide variation in SCSMV.Not Availabl