Correlation of intrusive growth of cambial initials to rearrangement of rays in the vascular cambium

Abstract

It is well documented that apical elongation of fusiform cambial initials through extension of their longitudinal edges, and their intrusion between tangential walls of the neighbouring initials and their closest derivatives cause rearrangement of fusiform cells, without increasing the cambial circumference. However, the concurrent rearrangement of rays is not fully understood. This study deals with Pinus sylvestris L., Tilia cordata Mill. and Hippophaë rhamnoides L., possessing a nonstoreyed, storeyed and double-storeyed type of cambium, respectively, and shows that the mechanism for rearrangement of ray initials is similar to the one proposed for fusiform initials, and includes multiplication of ray initials by anticlinal divisions, intrusive growth of ray initials, elimination of ray initials caused by intrusive growth of neighbouring fusiform initials, and transformation of ray initials into fusiform initials. Intrusive growth of a ray initial does not necessarily lead to the formation of a new fusiform initial, as it is dependent on the extent of the intrusive growth taken place. The extent of rearrangement of cambial cells is determined by the intensity of events occurring among the fusiform as well as ray initials. Intrusive growth of these initials does not influence the size of the cambial circumference.

Modelling for rearrangement of fusiform initials during radial growth of the vascular cambium in Pinus sylvestris L.

“…This hypothesis of the occurrence of intrusive growth along tangential walls explains why intrusive growth occurs always in conjunction with eliminations. This also confirms that neither the elimination nor the intrusive growth has an influence on cambial circumference (Jura et al 2006;Włoch et al 2009;Wilczek et al 2011). The occurrence of intrusive growth in one initial means an equal elimination of the adjacent initial, thus proving that the two events are complementry.…”

“…But this assumption is unable to explain phenomena such as the rapid rearrangement of initials in the old stem cambia (Włoch and Połap 1994;Włoch et al 2002;Karczewska et al 2009) or the tumorous cambia (Włoch 1976;Włoch et al 2001). According to newer findings, intrusive growth of the cambial initial occurs between the tangential walls of neighbouring initial cells and their immediate derivatives and, therefore, does not contribute to the circumferential enlargement of the cambial cylinder (Włoch et al 2001(Włoch et al , 2002(Włoch et al , 2009Kojs et al 2004a, b;Jura et al 2006;Karczewska et al 2009;Wilczek et al 2011). In fact, two adjacent initials (one growing intrusively, the other being eliminated) temporarily compete for the same area of initial surface and their subsequent periclinal divisions give rise to two unequal cells in each of these radial files (Jura et al 2006;Karczewska et al 2009;Włoch et al 2009;Wilczek 2012).…”

“…The intrusive growth and elimination, which have been described mostly as separate events, are actually two aspects of the same event (Kojs et al 2004a, b;Jura et al 2006;Włoch et al 2009). In transverse view, the incidence of intrusive growth may compel the tangential walls to occupy an anticlinal position and appear as a slanted wall (Jura et al 2006;Włoch et al 2009;Wilczek et al 2011). Recent investigations indicate that the main role of intrusive growth in the vascular cambium of trees pertains to relaxation of tensional strains generated during the growth of tree trunks and branches (Kojs and Rusin 2011).…”

Review: Assessment of the Doable Utilisation of Dendrochronology as an Element Tracer Technology in Soils Artificially Contaminated with Heavy Metals

“…In fact the wall structure and composition will be similar to that of a parenchyma cell. In addition, the newly formed elements are in very close proximity to the vascular cambium, and as lead will readily pass through the cambial tissue 57 it is conceivable that some proportion of bark-deposited lead may find its way into the walls of the newly differentiated xylem vessels. Also, lead from the transpiration stream in adjacent early-wood vessels, which will be functional, may find its way into the walls of the young elements and be deposited in this way.…”

Transcriptional regulation of vascular cambium activity during the transition from juvenile to mature stages in Cunninghamia lanceolata

“…Vascular cambium is a lateral meristematic tissue, which was frequently used as a key factor to indicate the vigor of tree growth (Wilczek et al, 2011;Hufkens et al, 2013). Numerous studies have largely focused on the regulation of vascular cambium activity in relation to seasonal cycles (Baba et al, 2011), and genetic networks responsible for stem cell maintenance (Elo et al, 2009;Miyashima et al, 2013).…”