Lace plant: a novel model system to study programmed cell death in plants
ID: 613 / 222
Proposed Symposium Title: Lace plant: a novel model system to study programmed cell death in plants
Affiliations: Department of Biology, Faculty of Science, Dalhousie University, Halifax, NS, Canada
Programmed cell death (PCD) plays a significant role in plant development and defense. One fascinating example of developmentally regulated PCD is perforation formation in the leaves of an aquatic lace plant (Aponogeton madagascariensis) in the family Aponogetonaceae. The formation of complex leaf shape through PCD is a rare event across vascular plants and occurs only in a few species of Monstera and in the lace plant. The evolutionary significance of leaf perforations remains unknown, although several hypotheses have been proposed. During early development, the lace plant leaf forms a pattern of equidistantly positioned perforations across its surface, giving it a lattice-like appearance. Lace plant leaves emerge from the corm in a heteroblastic series. The first 3–4 leaves that emerge are called juvenile leaves and do not produce perforations as they mature. Early-stage adult leaves are tightly furled and red due to anthocyanins and show no visible signs of cell death. As the leaves unfurl, PCD is initiated in the center of areoles, located between the longitudinal and transverse veins. The first visible sign of PCD is the disappearance of anthocyanins at the center of each areole, which then develops outwards and stops 4-5 cell layers from the veins. These peripheral cells that do not undergo PCD are named NPCD (non-PCD) cells. Many unanswered questions remain. Why does cell death always start at the center of areoles? Why does cell death stop from 4-5 cells from the veins? Why do cells display substantially different responses to PCD signals? At the mature stage of leaf development, perforation formation is complete, cells no longer undergo PCD, and mesophyll cells at the perforation border transdifferentiate as epidermal cells. The lace plant's suitability as a novel model to study PCD in plants will be discussed, covering plant morphology, evolutionary and molecular biology, and biophysics.