We investigated the influence of sorbitol, sucrose, fructose, glucose, maltose, lactose, and mannitol carbon sources at various concentrations on shoot proliferation, hyperhydricity and rooting of pear. Shoot tips were cultured in woody plant medium (Lloyd and McCown, 1981) containing 11.0 μm 6-benzyladenine, 0.5 μm indole-3-butyric acid, 0.8% (w/v) agar and 30, 60, or 120 mm of each of seven carbon sources for eight weeks. Sorbitol at 60 mm was the most effective carbon source for shoot proliferation. Using 30 mm sorbital and 30 and 120 mm sucrose resulted in a high number of hyperhydric explants. Shoots rooted with 60 mm glucose, sucrose and sorbitol in media; media with sucrose resulting in the highest rooting frequency, root number and root length. Shoots failed to root when fructose, lactose, maltose, or mannitol were used.
Masanori Kadota and Yoshiji Niimi
Masanori Kadota, Dong-Sheng Han and Yoshiji Niimi
Anthers of six apple [Malus ×domestica (L.) Borkh.], three Japanese pear (Pyrus pyrifolia N.) and two European pear (Pyrus communis L.) scion cultivars were cultured. Callus formation occurred from anthers of all cultivars and androgenic embryogenesis was observed from all except P. pyrifolia `Kosui' and P. communis `La France'. Regeneration of adventitious shoots from anther-derived embryos was shown from all apple cultivars and P. pyrifolia `Shinko'. Many of these shoots did not grow or died on half-strength Murashige and Skoog medium (1962) with 4.4 μm BA and 0.5 μm IBA, whereas several shoots of apple `Starking Delicious' grew to plantlets. Chromosome counts of shoot apical cells of four clones derived from embryos of `Starking Delicious' showed that three clones were diploids and one clone comprised diploid and haploid shoots, suggesting that at least one clone originated from a microspore. Chemical names used: 3-indolyl-butyric acid (IBA); N6-benzyladenine (BA).
Masanori Kadota, Takashi Hirano, Kiyotoshi Imizu and Yoshiji Niimi
Effects of PA on in vitro shoot proliferation and root formation were investigated using shoot cultures of three Japanese pear (Pyrus pyrifolia Nakai) cultivars. PA inhibited shoot multiplication and promoted initiation and development of roots in the cultured shoots of three cultivars, resulting in increasing the proportion of rooted shoots. Chemical name used: pyroligneous acid (PA).