Abstract
Polyamines (PAs) are aliphatic amines with low molecular weight that can be found throughout most living organisms. They are associated with a wide spectrum of cellular activities, such as growth, morphogenesis, or environmental stress response. In spite of the presence of PAs at considerable concentration, their physiological roles in plants yet remain as a subject to be explored. Here we present evidence showing that PAs are involved in rapid root abscission of the aquatic fern Azolla pinnata. The PAs spermine and spermidine induced rapid root abscission. Interestingly, spermine-NONOate, an nitric oxide (NO) conjugated form of spermine, showed much faster root abscission than that induced by the parent compound spermine. Because nitrite, an oxidized form of NO, also exhibited a similar root abscission, we consider it plausible that PAs may induce the root abscission of Azolla through the production of reactive nitrogen species in vivo.
