Autophagy regulates progression of programmed cell death during petal senescence in Japanese morning glory.

Petal senescence is a type of programmed cell death (PCD) that is tightly regulated by multiple genes. We recently reported that a putative membrane protein, InPSR26, regulates progression of PCD during petal senescence in Japanese morning glory (Ipomoea nil). Reduced InPSR26 expression in transgenic plants (PSR26r lines) resulted in accelerated petal senescence with hastened development of PCD symptoms, and transcript levels of autophagy-related genes were reduced in the petals. Autophagy visualized by monodansylcadaverine staining indicated reduced autophagic activity in the PSR26r plants. The results from our recent studies suggest that InPSR26 acts to delay the progression of PCD during petal senescence, possibly through regulation of the autophagic process. In this addendum, we discuss the role of autophagy in petal senescence as it relates to these findings.