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The organogenic potential of different explants is characteristic of kiwifruit and related species (Revilla et al., 1992; Ferguson et al., 1996; Oliveira and Fraser, 2005; Wang and Gleave, 2012). The response is dependent on the explant type and the level and combination of growth regulators used. Cytokinins are critical for the induction of the organogenic cultures. Shoot induction was obtained using zeatin or BA, although other cytokinins are effective, e.g. TDZ (Nayak and Beyl, 1987; Suezawa et al., 1988). Interactions between salt dilutions in the culture medium and the cytokinin concentrations were observed with nodal segments of ‘Hayward’ (Rey et al., 1992); reducing both factors increased shoot bud induction. Auxins, e.g. indoleacetic acid (IAA), at low levels also had a positive role (Rey et al., 1992). When auxins, i.e. naphthaleneacetic acid (NAA), are used at higher concentrations, the organogenic response is improved (Suezawa et al., 1988), whereas, 2,4-D has a negative effect (Oliveira, 1992, cited in Oliveira and Fraser, 2005).

Kim et al. (2007) described an efficient regeneration protocol using cross sections of shoots (800 μm thick) as explants; several explants are thereby obtained from a single stem with high shoot proliferation rates. The type of callus formed is a critical factor for indirect organogenesis induction (Suezawa et al., 1988; Rey et al., 1992; González et al., 1995c).

The organogenic potential of explants from male and female tissues differs and is related to the different endogenous cytokinin and auxin levels (Oliveira and Fraser, 2005). Female stem segments of A. deliciosa showed higher organogenic potential than male explants (Gui, 1979); whereas, male stamens produced callus and shoots but female ones produced roots (Brossard-Chriqui and Tripathi, 1984, cited in Ferguson et al., 1996). Explanted roots of the male ‘Tomuri’ regenerated shoots on medium with N6-2-isopentenyladenine, but not of the female ‘Hayward’ (Chiariotti et al., 1991). Hirsch and Bligny-Fortune (1979) reported the loss of chlorophyll in cell suspensions in the presence of 2,4-D derived from stem segments of female genotypes, whereas this did not occur with male genotypes. In ‘Hayward’ petioles, organogenic callus formation was restricted to the cut ends of the explant in contact with the induction medium (González et al., 1995c), but petioles from male cultivars responded by forming callus over the entire surface of the explants (Prado et al., 2007). Other factors, e.g. the level of sugar in the culture medium and the light quality, can affect organogenesis (Muleo and Morini, 1990; Leva and Muleo, 1993).