Browsing by Author "Roveraro, C"

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    In vitro culture of Quillaja saponaria Mol. (Soap-bark tree), Rosaceae
    (2004) Jordan, M; Roveraro, C
    Nodal sections of Quillaja saponaria, 'Quillay', including the proximal part of leaf laminae from 2-year old trees, as well as polynodal sections (3-4 axillary buds), were cultivated in MS-medium (MURASHIGE and SKOOG (1962) in the presence of various cytokinins, especially high levels of benzyladenine (BA) or thidiazuron (TDZ). This initiated profuse branching of the axillary bud and the induction of many new shoots and also callus formation in both explant types. From a single polynodal explant, more than 200 new multiple shoots developed in a period of 34 months. Proliferation of new shoots occurred mostly under the preexisting axillary bud(s) of the section and at the proximal end of the petiole with its intact leaf attached. Shoot clusters or isolated shoots elongated in subculture in the presence of MS-medium without growth regulators or formed roots when supplemented with indolebutyric acid (IBA) within a period of 30-60 days, leading to plantlets. Root formation occurred in 1/2 strength MS-medium with added 1 % sucrose and 0.6, 1.2 and 5.0 mg l(-1) IBA, as single hormone. Roots did not form in lower IBA levels (0.1 mg l(-1)) while the addition of phloroglucinol or thiamine did not enhance rhizogenesis besides the IBA. Despite the strong shoot initiation occurring in both nodal and polynodal explants, morphogenesis was not observed in leaf explant sections, and callus derived from nodal sections, formed green globular structures only without further differentiation.
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    In vitro regeneration of Gomortega keule (Gomortegaceae), a Chilean endemic tree in danger of extinction
    (2005) Jordan, M; Gonzalez, J; Roveraro, C
    Axillary buds of nodal sections from 2-year old trees of Gomortega keule (Mol.) Baillon, 'Queule', 'Keule', (Family: Gomorte gaceae) were induced to sprout and developed many shoots in presence of 0.54 mu M naphthaleneacetic acid (NAA) and 4.44 mu M benzylaminopurine (BA) in a liquid WP-medium (LLOYD and McCowN 1980) within a period of 2-3 weeks. After transfer to a medium containing 22.2 mu M BA, each new single node section of about 0.5 cm initiated numerous adventitious shoots; alternatively, roots were formed when these explants were transferred to a medium containing 2.95, 12.3 or 24.6 mu M indolebutyric acid (IBA). Root formation took place in presence of 24.6 mu M IBA in approx. 46 % of the sub-cultured nodal segments after a period of 3 months, leading to plandets. Regeneration response was restricted to the sprouts of axillary buds; other explant-types tested, i.e. petioles, leaf, and internodal sections showed callus formation only and no other responses.
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    In vitro regeneration of Sophora toromiro from seedling explants
    (2001) Jordan, M; Larrain, M; Tapia, A; Roveraro, C
    Embryonic axes with cotyledons, shoot-tips of embryonic axes, isolated cotyledons, as well as axillary buds and leaves from 20-year-old trees of Sophora toromiro, were evaluated for their capacity to trigger organogenesis and to regenerate plantlets under in vitro conditions. Embryonic shoot-tips were the only explants capable of regenerating plants. They developed rapidly in vitro in the presence of NAA and BA while in subculture roots were induced at the proximal end in the presence of 0.49 muM IBA within 40-60 days. Development was completed with a subculture phase under non-sterile conditions using a mixture of equal parts of sterilized vermiculite/sand/soil in growth chambers, before final acclimation in the greenhouse. In the presence of NAA, BA and GA(3), whole embryonic axes formed multiple shoots that branched when grown in 2.27 or 11.35 muM TDZ in subculture. Similarly, callus was initiated at the embryo axis base, developing into several new shoots in the presence of TDZ. Because of the relatively high shoot induction rate along the embryonic axis, this axis presents a valuable source of new juvenile explants. Growth and rhizogenesis was satisfactory only when organs from seed pods of the year or from the previous season were used. Experiments with isolated cotyledons produced callus only, while axillary buds and leaves did not show any responses in the presence of several growth regulators assayed. Inoculation of seedlings with various strains of rhizobia under in vitro conditions resulted in root outgrowths, but not in nodules that are typical of rhizobia infection.
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    Rapid in vitro propagation and microtuber production in Ullucus tuberosus (Basellaceae)
    (2002) Jordan, M; Amenábar, A; Roveraro, C
    A rapid in vitro propagation system leading to the generation of plantlets and microtubers was developed for Ullucus tuberosus. The method consisted of a two phase culture. The first started with nodal sections, each showing 3-4 axillary buds, and was the source of a large number of new shoots (max. 18.3 shoots/ flask) which formed within 15 days. Development of new shoots by axillary-bud sprouting and profuse shoot branching took place after 2-4 days in the presence of MS-media supplemented with various growth regulators including NAA, GA(3), BA or Z (Zeatin). The second phase, taking place after 15 days, consisted in subculturing single shoots to promote the production of roots and microtubers. Single shoots, transferred to a liquid (chromatogram paper-bridges) or jellyfied MS-agar medium in various levels of the indicated plant growth regulators, developed roots forming plantlets with I or more microtubers within 2 months. The highest tuberization yield was obtained in the presence of NAA (0.3 mg 1(-1)), BA (0.1 mg 1(-1)) and GA3 (0.01 mg 1(-1)) resulting in approx. 83 % tuber formation.