Induction of tetraploidy in Buddleia globosa

The aim was to produce a tetraploid form of Buddleia globosa to facilitate introgression of yellow flower colour into B. davidii, which is naturally tetraploid. Protocols were established for the micropropagation of B. globosa and tetraploid plants were obtained by application in vitro of colchicine to pre-cultured excised nodal sections. Three concentrations of colchicine were applied (0.01%, 0.05% and 0.1% w/v) for 1, 2 or 3 days. At 0.01% tetraploids were produced only after 2 days of application. All other treatments produced at least one tetraploid. The colchicine technique was extremely effective: of 29 lines tested, 19 were tetraploid and 5 were mixoploid. The vegetative characteristics of these tetraploids are described and the flowering characteristics of the three that flowered. This revised version was published online in August 2006 with corrections to the Cover Date.     

Anatomy of normal and hyperhydric leaves and shoots of in vitro grown Simmondsia chinesis (link) schn

Summary The anatomy of normal and hyperhydric in vitro shoots and leaves from micropropagated simmondsia chinensis (Link.) Schn. (jojoba) was compared with that of seedlings (control plants). In vitro normal plantlets displayed good development and survived during the acclimatization stage. In vitro hyperhydric plantlets presented numerous anatomical defects, such as hypertrophy of the mesophyll and of the stem cortex, malformed non-functional stomata, epidermal discontinuity, and xylem hypolignification; they did not survice acclimatization. The study of the anatomical features of in vitro jojoba shoots and leaves allowed determination of the structural condition of the plantlets and prediction of which plantlet would survive the critical acclimatization stage.     

A rapid in vitro propagation protocol for Piper barberi Gamble, a critically endangered plant

Summary A protocol is described for rapid multiplication of Piper barberi Gamble (Piperaceae) through shoot tip and nodal explant cultures. Nodal explants with a single axillary meristem showed three times better response with respect to shoot proliferation when compared to shoot tip explants. The best shoot proliferation response of nodal explants was observed with a cytokinin combination of N₆-benzyladenine (4.43 μM) and kinetin (2.32 μM), with 88% bud break. The number of shoot initials (2.4) produced per nodal explant was twice the number of shoot initials (1.2) per shoot tip. An average of 6.9±0.58 adventitious shoots were observed from the proximal end of the internodal explants on Mursashige and Skoog (1962) (Ms) basal medium supplemented with N₆-benzyladenine (2.22 μM) and kinetin (0.46 μM). A multiplication rate of 82 shoots per explant could be achieved after 9 wk of subculturing. The in vitro shoots were rooted on one-half and one-quarter MS basal medium. The shoots rooted on one-quarter MS in the dark produced eight roots with an average root length of 3.36 cm and 98% survival. These plants were transferred to the field with a survival rate of 75%.     

阳春砂仁微繁殖技术研究

以阳春砂仁的芽块为外植体,在附加1~6mg/L 6-BA的MS培养基上,可实现丛生芽增殖。最佳启动和增殖培养基为MS+5mg/L BA+5ml/L 20%硫代硫酸钠,出苗率和增殖率分别为62.5%和5.36。采用1/2 MS+1mg/L IBA+0.5mg/L IAA进行离体生根,生根率可达94.6%。     

Exogenous polyamines improve rooting of hazel microshoots

A strong positive effect of polyamines on rooting of microshoots of adult hazel (Corylus avellana L., cv. Gironell) is described. The effect of polyamines, both in the root induction solution and in the actual rooting medium, was assessed in order to study the effect on the successive rooting phases. Polyamines improved rooting of indole-3-butyric acid-treated microshoots in a synergistic fashion, perhaps by favouring a better induction of roots, with an acceleration of the response (only half the time required for rooting compared to the control). When applied without indole-3-butyric acid, polyamines had only a limited positive effect on rooting, although longer exposure times and/or higher concentrations could increase their effect. Possible rapid uptake and translocation of polyamines in the xylem in our system is discussed. The results offer a new approach to enhance rooting ability of species that are normally difficult to root.Abbreviations BM basal medium - IAA indole-3-acetic acid - IBA indole-3-butyric acid - NAA 1-naphthaleneacetic acid - Put putrescine - Spd spermidine - Spm spermine     

In vitro culture of Aloe Barbadensis Mill.: Micropropagation from vegetative meristems

A method for rapid and highly effective plant micropropagation from vegetative meristems was established for Aloe barbadensis Mill. Plant micropropagation was achieved culturing apices on medium containing 1.1 M 2,4-dichlorophenoxyacetic acid and 2.3 M kinetin for 15–30 days. High morphogenetic ability was maintained by transferring explants (after 60 days) on media containing 0.11 M 2,4-dichlorophenoxyacetic acid and 2.2 M 6-benzylaminopurine.     

Practical applications of in vitro propagation: Present situation and future prospects

Abstract

This article surveys the techniques and approaches used in the in vitro propagation of economically important plants. The current state of the art for each major class of plants, namely ornamentals, vegetable and agronomic crops, temperate fruits and forest trees is described. The advantages of vegetative propagation in general and the specific advantages which micropropagation offers in the domestication, breeding and conservation of plants are listed. Specific problems associated with in vitro propagation such as juvenility vs maturation, vitrification, rooting and morphological or physiological variations are discussed.     

The preparation in vitro of chrysanthemum for transplantation to soil

Plantlets of Chrysanthemum x morifolium were grown from nodal sections in cellulose plugs which were saturated with liquid rooting medium containing 1 mg l^–1 paclobutrazol in culture vessels that maintained relative humidities (RH) of 100%, 96% and 94%, respectively. After 4 weeks, plantlets were transferred to compost and exposed to 40% RH at 29°C. Marked differences in wilting were observed that were directly related to the RH of the vessel in which the plantlets had been grown. Thicker leaves, improved closure of stomata and increased thickness of the cuticle were associated with increased resistance to wilting. Reduced RH of the culture vessel was also associated with significantly higher concentrations of chlorophyll in the leaves.     

Optimization of in vitro bud induction and plantlet formation from mature embryos of Aleppo pine (Pinus halepensis Mill.)

Summary Studies were undertaken to optimize tissue culture conditions for micropropagation of Aleppo pine (Pinus halepensis Mill.) from mature embryos and various explants of the embryo. Over 90% of the embryo explants gave rise to adventitious buds within 4 wk. Intact embryos were the most suitable explants for shoot bud induction. Both isolated cotyledons and hypocotyls produced adventitious buds, but these developed slowly and failed to elongate. N⁶-Benzyladenine (BA) alone at 5.0μM was the most effective cytokinin when added to gelled to gelled von Arnold and Eriksson’s (AE) medium containing 3% sucrose. Adventitious bud development was achieved on hormone-free AE medium, and shoot elongation was optimum on three quarter-strength Bornman’s MCM medium, with 0.1% conifer-derived activated charcoal. Shoots were multiplied on three-quarter strength MCM medium, containing 5μM BA. To induce adventitious roots on the elongated shoots, pulse treatment with 1 mM IBA for 6 h, followed by the transfer of the shoots to sterile peat:vermiculite (1:1) mixture, was beneficial. After acclimatization for 3 to 4 wk under mist, almost all the rooted shoots could be transplanted successfully to the greenhouse, where the plants exhibited normal growth habit. Histologic studies on the ontogeny of adventitious shoot formation from mature embryo explants revealed temporal structural changes in different parts of the explant. Induction of mitotic divisions on the shoot-forming medium resulted in the formation of meristemoids in the epidermal and subepidermal layers of the explant, located initially at both the tips of the cotyledons and the axils of adjacent cotyledons. Shoot buds arising in the axils of adjacent cotyledons were due to new cell division and not to any preexisting meristem.     

Rapid in vitro propagation of Eclipta alba (L.) Hassk. through high frequency axillary shoot proliferation

An efficient protocol has been developed for rapid in vitro propagation of Eclipta alba L. (Asteraceae) through axillary bud multiplication. Murashige and Skoog (MS) medium supplemented with BA (10 M) was found to be most effective in breaking bud dormancy. An average number of 23 ± 0.57 shoots per explant was recorded after 30 days. Culture of node segments on fresh medium with lower concentration of BA (2 M) enhanced the multiplication rate. A maximum of 79 ± 1.90 mean number of shoots were obtained after three subcultures without any decline in multiplication rate. The regenerated microshoots showed the most efficient rooting on half strength MS medium augmented with 0.5 M IBA. Plantlets went through a hardening phase prior to ex vitro transfer and established in earthen pots containing garden soil; survival of about 90%. The established plants were uniform and exhibited morphological characters identical to mother plants.