Meristematic nodule culture: a new pathway for in vitro propagation of Eucalyptus globulus

Abstract

Morphogenesis was induced in Eucalyptus globulus seeds, cotyledons, hypocotyls and leaves from in vitro clonal plantlets. Globular structures were observed after 2 weeks induction on B5 culture medium supplemented with 10% coconut water, 0.05-0.5 mg l 1 6-benzylaminopurine (BAP) and 0.5 mg l 1 indole-3butyric acid (IBA). These continued to proliferate under dark conditions until the 2nd to 3rd subculture. Following transfer to a photoperiod of 16 h light, shoots evolved from these globular structures and developed further to plantlets. The influence of several factors, including culture medium composition, sucrose concentration, the type, concentration and combination of growth regulators and the presence of coconut water was studied. The percentage of explants showing globular structure formation and the number of globular structures per explant were evaluated. Macroscopic, histological and scanning electron microscopic studies revealed that the morphogenic process involved mainly organogenic nodules with fewer globular somatic embryos. The nodules gave rise to shoots and subsequently complete plants following incubation on B5 Gamborg medium containing 0.5 mg l 1 IBA and 30 g l 1 sucrose, which promoted root formation.

Efficient plant regeneration via meristematic nodule culture in Paeonia ostii ‘Feng Dan’

“…To our knowledge, this is the first report of MNs culture system capable of de novo shoot organogenesis in tree peony. MNs have been identified in both direct (Piéron et al 1993(Piéron et al , 1998Trindade and Pais 2003;Ferreira et al 2009;Moyo et al 2009), and indirect morphogenesis pathways through an intervening callus phase (Aitken-Christie et al 1988;Batista et al 2000;Fortes and Pais 2000;Xie and Hong 2001). In our studies, the MNs was initiated indirectly form calli derived from cotyledons of P. ostii 'Feng Dan', which was consistent with previous descriptions in P. lemoinei 'Golden Era' (Qin et al 2012) and P. rockii (zhong 2011).…”

“…Simultaneously, mixed use of CKs presented better response than single one, which was in accordance to results in Garcinia mangostana (Te-chato and Lim 2000). However, studies on Eucalyptus globulus showed contradictory results, BA enhanced both nodule induction and shoot organogenesis, but in the presence of CPPU, explants showed vitrification and no morphogenesis (Trindade and Pais 2003). This might be attributed to the fact that CPPU was far beyond its requirement on CKs activity.…”

“…CKs play a crucial role in in vitro morphogenesis. The appropriate CKs type for MNs induction and differentiation was genotype dependent, for example, BA was recommended for MNs induction of Radiata pine (Aitken-Christie et al1988) and Eucalyptus globulus (Trindade and Pais 2003), TDZ for Pelargonium × hortorum, Pelargonium × domesticum (Haensch 2004) and Acacia mangium (Xie and Hong 2001), CPPU for Eucalyptus botryoides (Ito et al1996). According to previous studies, high endogenous CKs promoted cell fate transition from callus cells to de novo shoot organogenesis by mediating up-regulated expression of WUS gene (Trifunović-Momčilov et al 2016;Gordon et al 2007;Meng et al 2017;Xiao et al 2018).…”

“…Successful in vitro regeneration through MN culture has been reported in several woody and herbaceous plants, such as Eucalyptus globulus (Dobrowolska et al 2017), Liquidambar orientalis (Bayraktar et al 2015), Populus euphratica (Ferreira et al 2009), Humulus lupulus (Fortes and Pais 2000), Sclerocarya birrea (Moyo et al 2009) and Billbergia zebrina (Dal Vesco et al 2011). The regeneration patterns were significantly affected by genotype, plant growth regulators (PGRs) and subculture time (Xie and Hong 2001;Trindade and Pais 2003). Therefore, the optimal culture conditions should be screened with genotype changes.…”

Histological and molecular insights in to in vitro regeneration pattern of Xanthosoma sagittifolium

“…Similar to a study on tree peony 15 , the regeneration of Xanthosoma involved four distinct phases that included callus with multiple meristematic regions, pre- nodules, meristematic nodules and shoot primordia. Formation of meristematic nodules either directly or indirectly via callogenesis has been reported in a number of species including Acacia mangium 16 , Eucalyptus globulus 17 , Humulus lupulus 18 , 19 , Populus euphratica 20 , Sclerocarya birrea 21 etc. Analogous observations have been made in a study on Elliottia racemosa 22 , in which in vitro regeneration from leaf explants took place via shoot organogenesis on a medium containing TDZ and IAA.…”