Is there an important role for reactive oxygen species and redox regulation during floral senescence?

Abstract

Senescence is a highly regulated process terminating with programmed cell death (PCD). Floral senescence, and in particular petal senescence, forms an interesting model to study this process in that floral lifespan is species specific and linked to biological function. A feature of petal senescence is a rise in reactive oxygen species (ROS) and a change in redox balance. A key question is whether this is merely a consequence of de-regulation of antioxidant systems as cells enter PCD, or whether the rise in ROS may have a regulatory or signalling function. An important division in the physiology of floral senescence is between species in which ethylene is a key regulator, and those in which it appears not to perform an important regulatory role. Another important question we can therefore ask is whether the redox and ROS changes have the same significance in species with different physiologies. Transcriptomic studies in ethylene-sensitive and -insensitive species allow us to further determine whether changes in the activity of ROS-scavenging enzymes are transcriptionally regulated during floral senescence. Finally, it is important to assess how a signalling role for ROS or redox status would fit with known plant growth regulator (PGR) control of floral senescence.