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Dirk R. Vuylsteke and Rodomiro Ortiz

In vitro-propagated plants of plantain (Musa spp., AAB group) did not manifest consistently superior horticultural performance compared to conventional propagules. Tissue culture plants grew vigorously and taller than sucker-propagated plants, but higher yield was not obtained, probably because of severe disease and suboptimal husbandry input. Phenotypic variation was higher in tissue culture plants, although this increase was not always statistically significant. There were no other detrimental effects of in vitro propagation on field performance. Botanical seed set rates for the two types of propagules were similar. The advantages of tissue-culture-derived plants as improved planting material would be most relevant for establishing field nurseries for further clean, conventional propagation of newly bred or selected genotypes.

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Joe-Ann McCoy and N.D. Camper

Hypericum perforatum L. (St. John's Wort) has an extensive history as an important medicinal herb used for the treatment of neurological and depressive disorders (Linde et al., 1996). The objective of this study was to establish an in vitro tissue culture protocol for St. John's Wort. Nodal segments, axillary buds, and leaf disc explants produced multiple shoots and callus on Murashige and Skoog minimal organics medium supplemented with combinations of indoleacetic acid (IAA; 0.57, 2.85, 5.71 μm) and benzylaminopurine (BA; 2.22, 4.44, 8.88 μm). Shoot production occurred on all combinations of IAA/BA tested and was significantly less in treatments without hormones. Callus production was higher on treatments containing 2.85 μm IAA + 4.44 μm BA, or 5.71 μm IAA + 8.88 μm BA. Shoots transferred to hormone-free medium at 8 weeks formed roots by 12 weeks. A micropropagation protocol was established for St. John's Wort using mature plants as the explant source.

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Marianela Ramirez, Marek J. Krasowski, and Judy A. Loo

Heuser, 1987 ). The purpose of this study was to further the development of vegetative propagation techniques for disease-free American beech, including tissue culture and grafting. This was done by: Experimenting with techniques to decrease in

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Mohd Faisal, Naseem Ahmad, and Mohammad Anis

1 To whom reprint requests should be addressed; e-mail anism1@rediffmail.com . The authors thank A K. Sharma, Deputy Director and Head, Tissue Culture Laboratory, National Botanical Research Institute (CSIR

Open access

P. H. Bressan, Y.-J. Kim, S. E. Hyndman, P. M. Hasegawa, and R. A. Bressan

Abstract

The node position from which axillary buds were isolated from shoots of rose (Rosa hybrida L.) markedly affected their growth and development in culture. Those buds nearest to and furthest from the apex either failed to develop or took the longest time to develop in culture compared to those buds in the middle portion of the stem. Benzylamino purine (BA) at low concentrations (0.03 to 0.3 mg/liter) stimulated the development of the axillary buds of ‘Gold Glow’ but not of ‘Improved Blaze’. A photon flux density (400-700 nm) of 17μE m−2 s−1 for 12 to 24 hours daily was optimum for the stimulation of shoot multiplication, while 66 μE mm−2s−1 for 12 to 24 hr was optimum for root initiation and for subsequent successful transplantation to soil of tissue culture-derived plants. A constant temperature of 21°C resulted in the highest rate of shoot multiplication and root initiation. Plants which initiated roots at 16, 21, or 26° had the highest level of transplant survival. An alteration in the temperature of the 8-hr dark period from 21° did not increase shoot multiplication, although root initiation was enhanced by lowering the night temperature to 11 or 16°. Histological analysis indicated that shoot multiplication of rose shoots occurs through the growth and development of axillary buds. The development of axillary buds is apparently under the repressive influence of the shoot apex, because physical excision of the apex or application to the shoot apex of 2,3,5-triiodobenzoic acid (TIBA) facilitated axillary bud development. Root initiation was affected markedly by the length of time that cultures had been maintained on shoot multiplication medium prior to transfer to rooting medium. This effect may be attributable to the BA in the shoot multiplication medium which may have accumulated in the tissue. If the endogenous cytokinin level is too high, root initiation may be inhibited and if it is too low the shoot undergoes senescence before it becomes cytokinin-autonomous, which occurs after root initiation.

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Xabier Barandiaran, Nieves Martín, María Fernanda Rodríguez-Conde, Antonio Di Pietro, and Jesus Martín

The influence of different callus induction media on the regeneration process in garlic was tested. The auxin 2,4 dichlorophenoxyacetic acid frequently used in garlic tissue culture was found to be detrimental when used at the levels described in the literature. However, combinations of growth regulators commonly used for dicot tissue culture produced high levels of callus induction and regeneration that could be used efficiently in a transformation program.

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Ravindra K. Hajela, Neerja Hajela, Mark G. Bolyard, Wayne M. Barnes, and Mariam B. Sticklen

A simple gene transfer method based on Agrobacterium -mediated transformation of adventitious multiplication of Juneberry (Amelanchier laevis L.) basal shoots is described. Evidence is presented for successful integration and expression of a transformed gene in greenhouse-grown transgenic plants. This method can transform woody perennials that are difficult to regenerate from leaf disks, protoplasts, or other tissue culture regimens.

Open access

Bruce J. Parliman, Phillip T. Evans, and Earlene A. Rupert

Abstract

A single rhizome explant of the Venus fly-trap has the potential to produce 14 or more rooted plantlets in 40 to 60 days when cultured on a medium containing half strength Murashige and Skoog salts, organic components, naphthaleneacetic acid (NAA) at 1.9 mg/liter and 6-benzylamino purine (BA) at 0.2 mg/liter. Cultures were grown in 16 hour cycles of Cool White fluorescent light at 23° to 26°C. Explants derived from either lateral buds or adventitious buds from leaf cuttings have equal potential for rapid multiplication. This same medium produced optimum plantlet size and quality. Supplementing the basal medium with 0.3 or 1.0 mg/liter of GA3 decreased the number of explants and increased the size of plantlets prior to acclimatization. Media containing higher and lower salt concentrations and higher and lower IAA, NAA, 2,4-dichlorophenoxyacetic acid (2,4-D), BA, or 6(γ,γ, dimethylallylamino)-purine (2ip), produced fewer plantlets while increasing deleterious effects. The rapid plantlet multiplication procedure described will increase commercial availability of the plants while decreasing collection pressures on wild germplasm pools.

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R.C. Apter, E.L. McWilliams, and F.T. Davies Jr.

One-node explants and one-node stem cuttings of Asian jasmine [Trachelospermum asiaticum (Siebold & Zucc.) Nakai] were rooted, respectively, in vitro [tissue culture (TC)] or by conventional macropropagation (MACRO). The TC and MACRO stem bases were then analyzed for differences in the time-course sequence of 1) root primordia initiation and development and 2) adventitious root xylem development and root-to-shoot xylem connections. Early root primordia were observed at Day 3, and, by Day 7, root-to-shoot xylem connections were equally developed in TC and MACRO systems. Continued development and emergence of adventitious roots were observed at Days 8 to 10. At Days 13 and 18, when viewed using scanning electron microscopy, TC root hairs were morphologically thicker and one-third to one-half the length of MACRO root hairs. There was no apparent difference in root-hair density. Inferior TC root-hair length may be a factor in the acclimation of TC-generated plantlets.

Open access

Hazel Y. Wetzstein and Harry E. Sommer

Abstract

The acclimatization or hardening-off of in vitro-cultured sweetgum (Liquidambar styraciflua L.) plantlets was studied using scanning electron microscopy. Comparisons were made among leaves of plantlets differentiated in culture, plantlets acclimatized after transfer from in vitro conditions, greenhouse seedlings, and mature trees. Leaves of plantlets directly from tissue culture had superficial, circular stomata and epidermal cells with irregular, sinuous undulations in the anticlinal walls. Leaves from acclimatized plantlets had ellipsoid, depressed stomata and irregularly shaped epidermal cells. Seedling and field-grown leaves had depressed, ellipsoid stomata and well-defined isodiametric epidermal cells. Stomata in all cases were confined to the abaxial surface, with densities significantly greater in leaves of in vitro plantlets than in acclimatized plantlets or greenhouse-grown plants. Epicuticular wax was generally smooth and absent of waxy outgrowths in all conditions.