Temporal and spatial expression of polygalacturonase gene family members reveals divergent regulation during fleshy fruit ripening and abscission in the monocot species oil palm

Peerapat Roongsattham, Fabienne Morcillo, Chatchawan Jantasuriyarat, Maxime Pizot, Steven Moussu, Dasuni Jayaweera, Myriam Collin, Zinnia H Gonzalez-Carranza, Philippe Amblard, James W Tregear, Somvong Tragoonrung, Jean-Luc Verdeil, Timothy J Tranbarger

Cell separation that occurs during fleshy fruit abscission and dry fruit dehiscence facilitates seed dispersal, the final stage of plant reproductive development. While our understanding of the evolutionary context of cell separation is limited mainly to the eudicot model systems tomato and Arabidopsis, less is known about the mechanisms underlying fruit abscission in crop species, monocots in particular. The polygalacturonase (PG) multigene family encodes enzymes involved in the depolymerisation of pectin homogalacturonan within the primary cell wall and middle lamella. PG activity is commonly found in the separation layers during organ abscission and dehiscence, however, little is known about how this gene family has diverged since the separation of monocot and eudicots and the consequence of this divergence on the abscission process.