Micropropagation of Araucaria excelsa R. Br. var. glauca Carrière from orthotropic stem explants

Abstract

The objectives of the present work were in vitro propagation of Araucaria excelsa R. Br. var. glauca Carrière (Norfolk Island pine) with focus on the evaluation of the mean number of shoots per explant (MNS/E) and mean length of shoots per explants (MLS/E) produced by different parts of the orthotropic stem of A. excelsa R. Br. var. glauca in response to plant growth regulators. Norfolk Island pine axillary meristems responded very well to the 2-iso-pentenyl adenine (2iP) and thidiazuron (TDZ) levels. Explants taken from stem upper segments in the media containing 2iP had a higher MNS/E (3.47) and MLS/E (6.27 mm) in comparison to those taken from stem lower segments, which were 0.71 and 0.51 mm, respectively. Using 0.045 μM TDZ in the MS medium not only resulted in 4.60 MNS/E with 7.08 mm MLS/E but proliferated shoots showed a good performance as well. Investigating the best position of stem explant on mother plant as well as the best concentrations of growth regulators were performed which were useful for efficient micropropagation of this plant. Thirty three percent of explants were rooted in the MS medium containing 3 % sucrose, supplemented with 7.5 μM of both NAA and IBA for 2 weeks before transferring to a half strength MS medium without any growth regulator. Plantlets obtained were acclimatized and transferred to the greenhouse with less than 20 % mortality. This procedure considered the first successful report for regeneration and acclimatization of A. excelsa R. Br. var. glauca plantlet through main stem explants.

Enhancement of Festuca rubra L. germination and seedling growth by seed treatment with pathogenic Agrobacterium rhizogenes

“…The transferred DNA (T-DNA) is integrated into the plant cell genome and, in consequence, the plant produces copious growth hormones (auxins and cytokinins) and opines which are beneficial for the bacterial growth. Several authors reported successful rooting in fruit trees and woody plants when using wild strains of A. rhizogenes (Damiano and Monticelli 1998;Haggman and Aronen 2000;Sarmast et al 2012). The IAA produced by bacteria colonizing the plant rhizosphere is considered to act in conjunction with endogenous IAA in plant to stimulate root proliferation and elongation, resulting in a more branched root system architecture, which in effect enhances the host's uptake of minerals and nutrients from the soil (Spaepen et al 2007;Shokri and Emtiazi 2010).…”

Gymnosperm Resprouting—A Review

“…Several authors have attempted to micropropagate various species of the Araucariaceae using small diameter stem segments, including Burrows et al [94] (9 Araucaria spp., 1 Agathis sp. ), Sehgal et al [102] (Araucaria columnaris), Iritani et al [60] (Araucaria angustifolia), Gough et al [103] (Agathis australis), Sarmast et al [104] (Araucaria heterophylla) and Niu et al [105] (Wollemia nobilis). These explants usually contained several nodes and internodes and buds developed from the axillary meristems.…”

“…Their progenitor meristems appeared to be endogenous but, as indicated above, were exogenous. Often medium to high concentrations of cytokinins, which can lead to enhanced axillary branching in dicotyledonous tree species, led to the formation of distorted buds [94,104,105]. A single bud developed in each axil.…”

Performance and genetic variation in a provenance test of Araucaria cunninghamii

“…Recent studies have shown development in the physicochemical characterization of its wood (McGavin et al, 2019;Fitzgerald & McGavin, 2020). The improvement of this species cultivation techniques has also been observed in different aspects (Sarmast et al, 2012;Lin et al, 2016;Matsabisa et al, 2019;Wang et al, 2020). In comparation to other more commercially valuable species such as loblolly pine and slash pine (Pinus taeda L. and Pinus elliottii, respectively), there has been less effort toward developing and deploying genetically improved and more productive individuals (Castillo et al, 2018).…”