Transgenic sugarcane resistant to sugarcane mosaic virus

Transgenic sugarcane plants containing the coat protein gene of sugarcane mosaic virus (SCMV) are resistant to subsequent infection by the virus. Three resistant phenotypes have been noted in the resistant plants. Plants exhibiting the 'immune' phenotype show no symptoms of viral infection after challenge inoculation and contain no virus. The second phenotype is 'recovery' in which the plants show symptoms on leaves that existed at the time of inoculation, but subsequent leaves show no symptoms and contain no virus. Both immune and recovery have been noted in other transgenic plant-virus systems. The third resistant phenotype is characterised by atypical symptoms of viral infection such as flecking, rather than the typical mosaic patchwork of chlorotic regions, but no virus is present. A number of the transgenic plants remained susceptible to infection by SCMV, eXhibiting the definitive mosaic symptom and containing high levels of virus. A trial to evaluate these plants for resistance to SCMV under field conditions has been established. Transgenic plants containing alternative constructs, based on the viral replicase gene, are being produced to increase the options for future deployment of transgenic SCMV -resistant sugarcane plants. These SCMV -resistant transge~ic plants have proved that virus resistance can be engineered into sugarcane: the technology and techniques developed in this and related research are being applied to begin the development of Fiji disease virus resistant transgenic plants.