Patterns of phenylpropanoids in non-inoculated and potato virus Y-inoculated leaves of transgenic tobacco plants expressing yeast-derived invertase

The patterns of secondary metabolites in leaves of yeast invertase-transgen ic tobacco plants (Nicotiana tabacum L. cv. Samsun NN) were analyzed. Plant s expressing cytosolic yeast-derived invertase (cytInv) or apoplastic (cell wall associated) yeast invertase (cwInv) showed a characteristic phytochem ical phenotype compared to untransformed controls (wild-type plants). The l evel of phenylpropanoids decreased in the cytInv plants but increased in th e cwInv plants, which showed an induced de novo synthesis of a caffeic acid amide, i.e. N-caffeoylputrescine. In addition, the level of the coumarin g lucoside scopolin was markedly enhanced. Increased accumulation of scopolin in the cwInv plants is possibly correlated with the induction of defense r eactions and the appearance of necrotic lesions similar to the hypersensiti ve response caused by avirulent pathogens. This is consistent with results from potato virus Y-infected plants. Whereas there was no additional increa se in the coumarins in leaves following infection in cwInv plants, wild-typ e plants showed a slight increase and cytInc a marked increase. (C) 2001 El sevier Science Ltd. All rights reserved.