Eradicating Sugarcane Yellow Leaf Virus in Sugarcane Variety N32 through Tissue Culture

Yellow Leaf Syndrome of sugarcane is caused by Sugarcane Yellow Leaf Virus (SCYLV) and/or Sugarcane Yellows Phytoplasma (SCYP). Using tissue blot immunoassay to determine the presence of SCYLV, leaf samples of sugarcane variety N32 taken from a propagation plot at Mount Edgecombe all tested positive. In this study, two methods of tissue culture were used in an attempt to eradicate SCYLV from N32. In the first method, meristems were excised and cultured on a medium containing 1 mg kinetin/litre, which caused the direct production of shoots (organogenesis). Although a moderate number of shoots were produced from the cultured meristems, the virus remained. The second method involved culturing immature leaf-roll discs on media containing 0.6 and 3 mg 2,4-D/litre for the production of callus (indirect somatic embryogenesis). An average of 58.8 plants per stalk were produced from discs cultured on the medium containing 0.6 mg 2,4-D/litre, whereas 31.5 plants per stalk were produced from the medium containing 3 mg 2,4-D/litre. Of the 202 plants regenerated, one plant tested positive for SCYLV. The culture medium containing 0.6 mg 2,4-D/litre produced the highest number of virusfree plants and thus proved the most efficient method of production.