Ontogenesis and structure of periderm in. Acer negundo L. and x Fatshedera lizei Guillaum

Abstract

The ontogenesis and structure of the periderm were investigated in two dicotyledonous plants: <em>Acer negundo</em> L. and x <em>Fatshedera lizei</em> Guillaum. In Fatshedera lizei periderm is produced by the monolayer of phellogen proper, whereas in <em>Acer negundo</em> sometimes cells in the immediate neighbourhood of phellogen proper, particularly the phelloderm participate in the formation of periderm. In Acer negundo at the boundary with the next annual phellem increment typical phelloid cells are present. Their thick walls contain pectins, cellulose and lignin, but do not contain suberin. The presence of phelloid was not detected in <em>Fatshedera lizei</em>. The walls of the phellem cells with horseshoe shaped thickenings of the inner tangential walls contain, beside pectins, cellulose and lignin, also a thin suberin layer directly on the primary walls. Thus, they are specifically shaped thickwalled cork cells. It is suggested to refer to the suberin layer jointly with the thick cellulose-lignin layer of the walls of thickwalled cork cells by the term "secondary wall". The term "tertiary wall (lamella)" is reserved for thin wall straw of the type of' "membranogenic stratum" and "warty stratum". In <em>Acer negundo</em> the structure of the suberin layers in the thick ceil walls of cork proper is cornplex.

The Making of Plant Armor: The Periderm

“…In the majority of cases a continuous periderm is formed in the first year of growth, however periderm formation can also be delayed for several years. For example, carob (Ceratonia siliqua) (5) and box elder (Acer negundo) (163) form first continuous periderm when they are approximately 6 years old. Several studies suggest that light intensity regulates the timing of periderm initiation: in fact, seedlings of red pine (Pinus resinosa), green ash (Fraxinus pennsylvanica), and black locust (Robinia pseudoacacia) maintained in the dark fail to form a phellogen, while exposure to light restore periderm initiation in a manner proportional to light intensity (19).…”

Periderm differentiation: a cellular and molecular approach to cork oak

“…The phellogen differentiates in the first years of growth not only in the epidermis, hypodermis, or phloem in most trees stem, but also in roots where it derives from the pericycle (Machado et al 2013;Wunderling et al 2018;Macnee et al 2020;Andersen et al 2021;Leal et al 2022a). However, in some species, such as carob (Ceratonia siliqua L.) (Arzee et al 1977) and box elder (Acer negundo L.) (Wacowska 1985) the first continuous periderm is formed in stems only in the sixth year. The formation of the phellogen results from the dedifferentiation of mature parenchyma cells (i.e., return to a meristematic function) by periclinal division.…”