BIPHASIC TEMPORAL AND SPATIAL INDUCTION-PATTERNS OF DEFENSE-RELATED MESSENGER-RNAS AND PROTEINS IN FUNGUS-INFECTED PARSLEY LEAVES

Previous experiments using in situ RNA hybridization have shown that t he mRNAs encoding phenylalanine ammonia-lyase, 4-coumarate:coenzyme A ligase, and pathogenesis-related protein 1 accumulated transiently aro und fungal infection sites in parsley (Petroselinum crispum) leaf buds . These studies have now been extended by (a) analyzing different stag es of the infection process and (b) monitoring the timing of appearanc e and the spatial distribution of the proteins as well as the correspo nding mRNAs. An early and short period of mRNA induction throughout a large portion of the infected leaf was followed by a longer period, du ring which the mRNA levels remained high in a more localized area arou nd the site of fungal penetration with sharp borders toward the surrou nding tissue. This biphasic pattern of mRNA accumulation was followed after some delay by the same pattern of protein accumulation.