Abstract
Polyamines (PAs) - putrescine, spermidine and spermine (Spm) - are low molecular weight organic cations that are implicated in various physiological and developmental processes in all organisms including plants. Of these, we are interested in Spm action in plants. It was reported that tobacco mosaic virus (TMV)-infected tobacco leaves contain higher levels of Spm in the intercellular spaces. Moreover, Spm application to healthy tobacco leaves induced expression of PR genes. These findings indicate that Spm is closely related with the resistance against plant pathogens. Here we isolated Spm-responsive genes from tobacco using a differential screening method and identified HIN1 gene. Other PAs have no effect on HIN1 induction. The induction was inhibited by antioxidant treatment. These results suggest that Spm induces HIN1, a HR maker gene, via reactive oxygen species-induced signal transduction pathway.
