Decreased level of ferredoxin I in Tobacco mosaic virus-infected tobacco is associated with development of the mosaic symptom

A decrease of ferredoxin I (Fd I) level was detected in the Tobacco mosaic virus (TMV)-infected tobacco (Nicotiana tabacum) leaves and the extent of decrease was uneven in the leaves showing mosaic symptoms. The Fd I level in the dark-green regions which contain less TMV was higher than that in the chlorotic regions of the same leaf, but was lower than that in the healthy control plants. The N. benthamiana plants with the Fed-1 gene being silenced by a chimeric viral vector showed chlorotic and yellowish phenotype in which H2O2 accumulated to a high level. In antisense Fed-1 transgenic N. benthamiana plants, the multiplication of TMV in infected plants and the accumulation of the viral coat protein in the chloroplasts were enhanced by the decrease of Fd I. Taken together, these results suggest that the unevenly decreased level of Fd I in TMV-infected tobacco leaves may contribute to the expression of chlorosis and mosaic symptoms.