Ontogeny in terminal buds of Abies nordmanniana (Pinaceae) characterized by ubiquitin

Abstract

Meristematic activity in the bud meristem of Abies nordmanniana was visualized by ubiquitin immunohistochemical localization from before bud break and throughout shoot expansion. Ubiquitin was detected in meristematic cells either in the cytosol or nucleus, or both, depending on tissue type and developmental stage. During winter dormancy, ubiquitin was only observed in the protodermal/hypodermal layers, but at bud break in mid May, the signal expanded to the entire shoot tip. At the end of May, a clear zonation in ubiquitin localization appeared that lasted about one month. Throughout this period, ubiquitin was barely detectable in a central group of cells that might indicate an organizing center with stem cells. At the end of June, coinciding with the transition from scale leaf to needle primordia production, ubiquitin again was more prevalent in the peripheral cell layers. During shoot expansion, a strong ubiquitin signal developed in the axil of all needles. Most of these signals later disappeared, except for those few axils where buds actually developed. A strong ubiquitin signal was also observed in cells lining the young resin ducts. Our data showed that ubiquitin may be used as a marker for metabolic activity associated with seasonal development in the apical meristem.

Partial shoot reiteration in Wollemia nobilis (Araucariaceae) does not arise from ‘axillary meristems’

“…There can be a phase of partial differentiation of a normal axillary bud before axillary cells turn meristematic again. Further modification is supported by the demonstration in Veierskov et al (2008) that by localizing ubiquitin they could find initial stages of axillary bud development in the axils of all needles in Abies nordmanniana. However, few of these initial stages achieve the status of visible buds.…”

“…Research on branch expression in conifers is extensive, as indicated in the literature surveys of Rasmussen et al (2005Rasmussen et al ( , 2010 and Veierskov et al (2008), but studies on branch development in traumatic circumstances are very limited, even though they may have direct commercial significance in the production of 'greenery' [lateral branch complexes cut for Christmas decoration; Rasmussen et al (2005)]. The literature on the control of shoot form in conifers has moved from the early descriptive approach to one in which the influence of phytohormones is being extensively investigated (e.g.…”

Gymnosperm Resprouting—A Review

“…In saplings of Abies nordmanniana meristematic activity was visualised by ubiquitin immunohistochemical localisation. The staining indicated that the initial stages of axillary bud initiation began in the axils of all needles, but the signal transduction pathway did not proceed, meaning that buds were not formed except in a few axils [77]. In the same species, Briand et al [78] noted that leaves appeared to have 'empty' axils but in certain axis orders buds could develop.…”

Characterization of Top Leader Elongation in Nordmann Fir (Abies nordmanniana)

“…In the shoot of most conifers such as spruce, pine and fir, needle insertions into the top leader generally lack axillary buds (Veierskov et al 2008). Thus, the terms node and internode are not applicable terms for these plants; instead, the term stem unit is used.…”