The classic symptom of Fiji disease is raised whitish galls on the abaxial side of the leaf laminae. Increased disease pressure on moderately susceptible cultivars such as Q124 has resulted in restrictions on the areas where these cultivars can be grown or the premature plough-out of infected crops. Fiji disease resistant variants of Q124 have been produced by microprojectile transformation of Q124 embryogenic callus with a translatable version of the FDV segment 9 ORF 1, under control of the maize ubiquitin promoter and the Nos termination sequence. Transgenic lines were tested in glasshouse trials by caging the plants and controls with Perkinsiella saccharicida planthoppers that had been previously bred on FDV-infected plants. After two weeks the planthoppers were killed and the development of symptoms followed.
Some resistant lines show few or no symptoms of Fiji disease, whilst others express some galls.
Initial molecular analysis of the various transgenic lines suggests little relationship between transgene copy number and resistance status.