0000000000312009
AUTHOR
M. C. Brisa
Somatic embryogenesis from hypocotyl callus cultures of Digitalis obscura L.
Hypocotyl-derived calli obtained in agar solidified medium with several growth regulator combinations gave rise to proembryonal masses and globular embryos when transferred to liquid media with lower growth regulator and higher NH4HO3 levels. By transferring cultures from liquid media to different solidified media, new embryo formation took place, but further development of these embryos or those previously induced depended on the characteristics of these media. Normal development was only achieved on 8 g/l agar solidified medium without growth regulators. Typical cotyledonary embryos developed into whole plants when transferred to this same medium.
Isolation, culture and plant regeneration from mesophyll protoplasts of Digitalis obscura
High yields of protoplasts were obtained from mesophyll tissue of Digitalis obscura L. Osmotic potential of the isolation medium and Ca2+ were important in obtaining a high viability of the preparations. In different culture techniques employed, liquid-over-agar-solidified medium was superior to liquid medium alone. Agar plating technique was ineffective. On Murashige and Skoog modified medium with casein hydrolysate and several indoleacetic acid and benzyladenine combinations, isolated protoplasts underwent sustained mitotic division and produced calli. The calli formed shoots when transferred to regeneration media. Regenerated shoots could be easily rooted and developed into whole plants …
Influence of culture conditions on embryo formation and maturation in auxin-induced embryogenic cultures of Digitalis obscura.
Somatic embryogenesis was induced in hypocotyls of Digitalis obscura using indoleacetic acid or 2,4-dichlorophenoxyacetic acid with different culture and subculture conditions. Indoleacetic acid-induced embryogenic cultures were used to investigate the effects of amino acids, polyamines and growth regulators on embryo differentiation and maturation. Supplementation of the media with amino acids, polyamines or abscisic acid did not influence or had an adverse effect on embryogenic response. Gibberellic acid at 1.4 μM in either culture (30 days) or subculture medium was effective in promoting both differentiation and normal embryo development. The efficiency of somatic embryogenesis was great…
Factors Influencing Digitalis Obscura Mesophyll Protoplast Development
In a previous work (1), we found that a combination of liquid-over-agar-solidified MS (2) modified medium was superior to either all liquid or all solid medium for culture of Digitalis obscura L. mesophyll protoplasts. In order to achieve optimum culture conditions we now report on the influence of a different gelling agent (agarose) as well as the effect of several nutrient media on D. obscura mesophyll protoplasts development.
Somatic Embryogenesis and Plant Regeneration from Hypocotyl Cultures of Digitalis obscura L.
Summary Hypocotyl sections from 20-day-old seedlings of Digitalis obscura L. were used to examine the effect of IAA on somatic embryogenesis. Although embryogenesis was obtained with all IAA concentrations (0.1, 0.5 and 1 ppm) and under both illumination conditions tested (16 h photoperiod and darkness), incubation in photoperiod increased yield of embryos and shortened the embryo induction time. Optimum results were obtained with 1 ppm IAA. About 30 % of the embryos obtained developed into complete plantlets when transferred to basal medium without growth regulators.
Morphogenic potential of mechanically isolated single cells from Digitalis obscura L. callus
Calli from hypocotyl and root explants of Digitalis obscura L. showed regeneration of adventitious shoots, roots and embryos when transferred to Murashige & Skoog medium supplemented with cytokinins alone or in combination with auxins. Optimum shoot-bud formation was achieved in the presence of IAA and BA, while roots mainly appeared either in absence of growth regulators or with IAA and Kn. Embryo formation took place only in those combinations that included Kn. Embryo development was influenced by the type of auxin, and precocious germination occurred in media with NAA. Mechanically isolated cells from hypocotyl- and root-derived calli were plated in MS medium supplemented with several IA…
Morphogenesis and Cardenolide Formation in Digitalis obscura Cultures
Summary Cardenolide formation was investigated in hypocotyl cultures of Digitalis obscura L. established on MS medium with growth regulators selected to promote either callus formation, caulogenesis, embryogenesis or rhizogenesis. Examination of the cardenolide composition of leaves from mature plants was also performed. Several compounds of series A and C were identified by HPLC in in vitro and in vivo grown tissues, no marked differences being found between their cardenolide patterns. RIA determinations showed that shoot- or embryo-forming calli accumulated significantly higher amounts of digoxigenin derivatives than undifferentiated or rhizogenic cultures. In any case, field plants prese…
In vitro morphogenesis from excised leaf explants of Digitalis obscura L.
The morphogenic capacity of Digitalis obscura leaf explants cultured in vitro has been studied, noting factors promoting the differentiation of roots, buds and shoots as well as those promoting callus proliferation. Complete plant regeneration was obtained only by first culturing the leaf explants in a medium with NAA and BA to induce formation of buds, and subsequently transferring them to a medium without growth regulators to achieve the further development of shoots.