Carbohydrate partitioning and sugar signalling in Cauliflower mosaic virus-infected turnip and Arabidopsis

We analyzed the correlation between the development of symptoms, virus titre and carbohydrate levels in turnip and Arabidopsis during infection with four isolates of Cauliflower mosaic virus (CaMV). Infection did not significantly affect sugar levels in source leaves except at the very late stages (28 d.p.i.), but induced a three-fold but short lived increase in sink leaves. Titres of severe isolates were greater than mild isolates, but we observed no obvious correlation between sugar levels and symptom appearance. In wild-type Arabidopsis, infection did not stimulate increased sugar levels, but did so in a mutant, cnr160, which shows altered growth-response to high carbon and low nitrogen. These results do not support a direct role for sugar-mediated control of symptom development during virus infection.