Uptake and translocation of [¹⁴C]‐labelled benzylaminopurine in apple shoots grown in vitro in relation to shoot development

Abstract

Shoots of apple (rootstock A2, Malus sylvestris (L.) Mill var. domestica Borkh.) were grown in vitro on agar media containing 4.4 μM benzylaminopurine (BAP) during the whole of a 36‐day culture period or during the first 6 days of the period. Development of lateral shoots and an appreciable increase in fresh weight were obtained only when BAP was present during the whole period. Treatment for 6 days only was not sufficient for shoot proliferation although the transferred shoot continued its growth on fresh medium without BAP. Uptake of the cytokinin was studied by adding [8–14C]‐benzylaminopurine to the medium and then following the distribution of the isotope in the shoots during the 36‐day culture period. There was a steady, almost linear, uptake of 14C during the whole period. Most of the activity accumulated in the lower part of the shoot. It is concluded that BAP, due to slow translocation, is active mainly in the basal parts of the shoot where it stimulates formation and growth of buds. Its action is dependent on continuous supply of new BAP from the medium, indicating metabolism of BAP in the tissue.

Effect of applied and internal hormones on vitrification and apical necrosis of different plants cultured in vitro

“…It has been shown that BA is readily taken up by shoots from the medium (Minocha & Nissen, 1982;Nordstr6m & Eliasson 1986;Marino 1988). Agar influences the availability of cytokinins (Debergh 1983) and there exists an inverse correlation between uptake of 14C-labelled BA and agar concentration in the medium (Bornman & Vogelman 1984).…”

CO2-enriched microenvironment affects sucrose and macronutrients absorption and promotes autotrophy in the in vitro culture of kiwi (Actinidia deliciosa Chev. Liang and Ferguson)

“…These are (1) change from heterotrophic to autotrophic nutrition, which affects sucrose and ion absorption (Kozai et al 1991); (2) changes in the medium pH, which can alter ion solubility (Kozai et al 1991); and (3) increasing evapotranspiration of the explants through ventilation, thus lowering environmental relative humidity versus traditional culture in a water vapor saturated atmosphere. It has been shown that cellulose plugs used as explant support in liquid medium can influence mineral uptake because of ion adsorption by the cellulose fibers (Nordstrom and Eliasson 1986).…”

Characterization of Two Gene Transcripts Modulated by Cytokinins in Micropropagated Apple (Malus domestica [L.] Borkh) Plantlets

“…In the culture medium have been reported to greatly influence both growth and morphology of the shoots produced during the proliferation process (6,25). The uptake and distribution of the applied cytokinin in micropropagated apple plantlets have also been documented (16). However, at present, little is known about the molecular mechanisms underlying cytokinin action in axillary bud growth stimulation.…”