Epidemiological Studies and Molecular Characterization of Phytoplasma Associated With Sugarcane

Abstract

A survey conducted during two years (2017-2019) in Meerut, Muzaffarnagar, Saharanpur and Shahjahanpur districts of Uttar Pradesh, India revealed the presence of sugarcane grassy shoot disease. Symptomatic as well as non-symptomatic sugarcane plants were examined for phytoplasmal infections by means of polymerase chain reaction (PCR) technology, using primers directed to phytoplasma ribosomal DNA (rDNA) sequences. The phytoplasma presence was confirmed in 61 out of 107 sugarcane plants by highly sensitive nested-PCR assays using universal phytoplasma primers. The phylogenetic relationships of SCGS phytoplasma strains including those whose 16SrDNA sequences were determined in this study, to each other and to other closely related phytoplasmas, at both 16S rRNA gene and 16S/23S rDNA spacer region sequence levels were examined. The SCGS phytoplasma is in the study was found to be associated with phytoplasma 16SrXI group, and proved very closely related to the sugarcane with leaf (SCWL) agent. Subgroup based classification demonstrated that sequences with accession numbers: Meerut- MN124377, MN124378, MN124368; Muzaffarnagar- MN136044, MN136051, MN124371 and Shahjahanpur-MN124369 belongs to 16Sr XI B subgroup. SCGS sequences with accession no. MN136048, MN124369 from Shahjahanpur and MN124372 from Muzaffarnagar represent to be a member of 16Sr X-C sub group. Whereas, SCGS sequences with accession numbers MN136049 from Meerut was found to be associated with 16Sr XI-F subgroup. This is the first report of 16Sr XI-F subgroup phytoplasma on sugarcane from northern India. More distantly related to the SCGS agent, are sorghum grassy shoot (SGS), Bermuda grass white leaf (BGWL) (‘Candidatus Phytoplasma cynodontis’) and RYD (‘Candidatus Phytoplasma oryzae’) phytoplasmas. The results of the study indicate the importance and wide spread of this disease in the state and its impact with severe losses on yield and quality parameters of the sugarcane.