The role of cytokinins in shoot organogenesis in apple

Abstract

Effective regeneration in vitro is a necessary precondition for the implementation of different biotechnological approaches in plant breeding. Numerous studies have reported on regeneration from apple somatic tissues, and organogenesis has been proved to be influenced by several factors including mother shoots (genotype, size, type, and age of explant), in vitro conditions (dark period, light intensity, and quality), and others (wounding, orientation of leaf explants). However, one of the most important factors before and during the regeneration process is the type and concentration of cytokinin applied. Thidiazuron and benzyladenine are the most frequently used cytokinins in the regeneration systems, but their efficiency depends on genotype and other factors. Other cytokinins (e.g., zeatin and kinetin) have also been tested in several experiments and they were found in general to be less active. The organogenic ability of explants can also be increased by a properly selected cytokinin pre-treatment. Cytokinins applied in the pre-treatments can influence the leaf structure, which in turn can alter the regeneration capacity of the leaf explant. Interactions between factors of pre-treatments (hormones, light, and culture conditions) and factors of the regeneration phase should be considered. This review brings into focus the role of different cytokinins during in vitro shoot development, discussing their effects on the histology of leaves developed in vitro, and how this affects the subsequent regeneration process.

An improved protocol for in vitro propagation of the medicinal plant Mimosa pudica L.

“…This result was corroborated by Žiauka and Kuusienė (2010), who observed complete inhibition in root formation when Populus tremula L. nodal segments were treated with high doses of paclobutrazol, an antagonist molecule of gibberellin synthesis, indicating that GAs, in low concentrations, may become beneficial to root development. Apparently, reduced doses of GA 3 , when associated with BAP, increase the effectiveness of in vitro propagation processes, particularly in explants elongation and root formation phases (Pati et al, 2006;Magyar-Tábori et al, 2010). However, in this study, the beneficial effects of gibberellins were not observed for M. pudica.…”

<i>In Vitro</i> Propagation and Recovery of Eight Apple and Two Pear Cultivars Held in a Germplasm Bank

“…Other cytokinins such as Zea, 2iP and kinetin [37] are less commonly used, and the use of phenylurea derivatives such as thidiazuron and N-2-chloro-4-pyridyl)-N-phenylurea (CPPU) is sometimes described on shoot proliferation in pear cultures [38]. However, theeffectiveness of any of these cytokinins in the multiplication medium will depend primarily on the genotype of the cultivar [28].…”

“…Furthermore, the risk of mutation in clones derived from axillary buds is much lower than the risk of mutation during organogenesis from callus. Both BA and TDZ are the most frequently used cytokinins in apple regeneration and they have been compared in several studies [28]. TDZ has been found to be more effective than BA for shoot regeneration in numerous trials [25] [41] [42].…”

“…In vitro micropropagation has been reported in several cultivars of apple [13] and pear trees propagated in vitro [14] [28], but their efficiency depends on genotype and other factors [22]. Other cytokinins such as zeatin, 2iP and kinetin have also been tested in several studies and have generally been found to be less active [28]. The development of axillary buds as a multiplication method has been used in some fruit cultivars [29] as is one of the most effective methods of maintaining the genetic stability of cultivars.…”

Efficient and new method for Tectona grandis in vitro regeneration

“…In particular, the relationship between the applied plant growth regulators and the explant's ability to respond to the stimuli provided by the plant growth regulators determines organogenesis (Find et al 2014). Therefore, successful plant regeneration in tissue culture involves multiple processes, including signal transduction and perception of stimuli from plant growth regulators, redifferentiation of the dedifferentiated tissues, subsequent cell division, and organization to form organs (i.e., root, shoot) (Magyar-Tábori et al 2010, Almeida et al 2015. Cytokinins added to the regeneration medium can enhance cell competence for the development of new shoots and therefore increase the number and frequency of regenerating shoots and their subsequent growth rate (Hartmann et al 2011).…”