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Antonio Figueira, Anna Whipkey, and Jules Janick

Axillary shoots of cacao (Theobroma cacao L.), induced in vitro with cytokinins (BA or TDZ), elongated and produced leaves only in the presence of cotyledons and/or roots. Detached axillary shoots, which do not grow in `vitro under conventional tissue culture protocols, rooted with auxin and developed normally in vivo. Detached axillary shoots from cotyledonary nodes and single-node cuttings from mature plants were induced to elongate and produce normal leaves in the presence of 20,000 ppm CO2 and a photosynthetic photon flux density (PPFD) of 150 to 200 μmol·s-1·m-2. Subculture nodal cuttings continued to elongate and produce leaves under elevated CO2 and light levels, and some formed roots. Subculture of microcuttings under CO2 enrichment could be the basis for a rapid system of micropropagation for cacao. Chemical names used: N -(phenylmethyl) -1 H -purin-6-amine (BA); 1 H -indole-3-butyric `acid (IBA); α -naphthaleneacetic acid (NAA); thidiazuron (TDZ).

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Kazuhiko Mitsukuri, Takaya Arita, Masahumi Johkan, Satoshi Yamasaki, Kei-ichiro Mishiba, and Masayuki Oda

an alternative method is required to meet the market demand. Micropropagation of orchid plants has been studied extensively, and mericlones of Cymbidium ( Morel, 1960 ), Cattleya ( Reinert and Mohr, 1967 ), Dendrobium ( Kim et al., 1970 ; Roy

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Sandra B. Wilson, Robert L. Geneve, and Fred T. Davies

, NY). The student is asked to drag and drop the stages of micropropagation in proper order ( University of Florida, 2018 ). After the SUBMIT button is clicked, the question is graded for immediate feedback. The menu to the left outlines all the

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E. Kiss, J. Kiss, G. Gyulai, and L.E. Heszky

A novel micropropagation method for pineapple (Ananas comosus L.), based on shoot elongation induced in vitro, was demonstrated for two cultivars. Decapitated in vitro plantlets were used as explants. Shoot etiolation was induced by placing explants in a Murashige and Skoog (MS) medium containing NAA (10 μm) and incubating in darkness at 28C for 30 to 40 days. The mean number of the regenerated etiolated shoots per explant was 2.6 ± 0.29. The etiolated shoots were placed into N6 medium supplemented with kinetin or BA (25 or 20 μm, respectively). After 4 to 6 weeks, shoots regenerated along the nodes. The highest regeneration rate was 15 and 13 plantlets per node with 25 μm kinetin and 20 mm BA, respectively. Regenerated plantlets were rooted on a growth-regulator-free MS medium. Residual shoots of the initial explants could be recycled by rooting on a growth-regulator-free MS medium. This procedure enables the regeneration of several thousand plantlets per year. Chemical names used: naphthaleneacetic acid (NAA); benzyladenine (BA).

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Sherry Kitto and Jeanne Frett

Hexastylis shuttleworthii is a highly ornamental shade-tolerant evergreen herbaceous plant native to the southeastern U.S. that is difficult to propagate using traditional methods. Micropropagation would make possible the wider distribution of selected clones. Seeds were surface-sterilized and germinated in vitro. Seedling clones were maintained on a MS basal medium containing 1 mg/L BA and were subcultured monthly. Proliferation of clones 2 and 3, maintained on media supplemented with 1, 2.5 or 5 mg/L BA for 6 months, increased slightly with increasing BA concentration; however, proliferation decreased slightly over the experimental period. Rooting medium (perlite, vermiculite, MetroMix 510, Bacto Growers Mix) did not effect microcutting root production or subsequent plant survival. Microcuttings rooted in vitro (67% survival) generated more leaves compared to microcuttings rooted under humidity domes with mist in the greenhouse (8% survival). After rooting in vitro, multiple-shoot clumps (95%) survived better than individual shoots (29%) under greenhouse conditions. Plants were easily established when planted in raised beds in a lath house.

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Chunsheng Lu, Yiqin Ruan, and Mark Bridgen

Micropropagation has been used to rescue Leontochir ovallei, an endangered Chilean species in the Alstroemericeae. Cultures were initiated by aseptically germinating seeds of Leontochir on a medium containing 1/10 MS salts and vitamins and 0.3% sucrose. Three types of cytokinins (BAP, 2-iP and kinetin) at four concentrations (0, 2, 4, and 8 uM) were studied for shoot proliferation. In the 4 uM BAP treatment, new shoots were produced at an average of six per culture after four weeks of culture. Overall, there was an average of four shoots/culture/4 weeks for all BAP treatments. This was significantly higher than the 2-iP and kinetin treatments. Moreover, the increase of culture fresh weight over time was significantly greater in BAP treatments than those in other treatments. A rooting study compared the effect of NAA and IBA on root initiation. Over 85% of the cultures in 10 and 20 uM NAA treatments produced healthy and large roots. This was significantly higher than the 10 and 20 uM IBA treatments. In summary, a concentration of 4 uM BAP combined with 1 uM IBA in MS salts and vitamins supplemented with 146 mg glutamine/l is the best for shoot proliferation of leontochir; an MS basal medium containing 10 uM NAA is the best for root initiation. Micropropagated plantlets have been successfully transplanted into the greenhouse for further genetic and breeding studies.

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M. Cristina Pedroso, M. Margarida Oliveira, and M. Salomé S. Pais

Nodal segments and shoot tips of axenic shoot cultures of `Hayward' kiwifruit were inoculated on modified Murashige and Skoog (MS) medium supplemented with zeatin at 1 mg·liter-1 and IAA at 0.05 mg·liter-1 (H1) or on MS medium without growth regulators (H2). Inocula cultured on H2 medium all developed into normal plantlets, while those cultured on H1 medium developed into shoots, 18% of them abnormal. Rooting of H1 shoots was induced by a 24-h immersion in a solution of IRA at 20 mg·liter-1. H2 plantlets were directly transferred to soil. Statistical treatment of the results revealed no significant differences, in terms of plant development, between the two micropropagation methods used. However, the presence of a functional root system on 5-week-old H2 plantlets resulted in 100% plant survival, but only 70% of in vivo-rooted shoots from H1 survived. Nevertheless, H1 still allowed for an important reduction of costs and manipulation. Chemical names used: indole3-acetic acid (IAA).

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Flávia D. Pereira, José Eduardo B.P. Pinto, Luciana D.S. Rosado, Helen C.A. Rodrigues, Suzan K.V. Bertolucci, and Osmar A. Lameira

plants to grow in different environments, micropropagation techniques can be used to produce large quantities of rooted and disease-free propagules. Plants that have been micropropagated in the partial or complete absence of light form micropropagules

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Toktam Taghavi, Alireza Rahemi, Reza Rafie, and Maru K. Kering

acetic acid (NAA), and 6-furfurylamino purine [kinetin (KT)], are commonly used by most researchers for micropropagation ( Panda et al., 2007 ). BAP is the most preferred PGRs for shoot elongation and multiplication, and NAA is generally known to promote

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M.E. El-Mahrouk, A.R. El-Shereif, Y.H. Dewir, Y.M. Hafez, Kh. A. Abdelaal, S. El-Hendawy, H. Migdadi, and R.S. Al-Obeed

commercial plant micropropagation ( Piqueras et al., 2002 ; van den Dries et al., 2013 ). Consequently, hyperhydricity can limit the success and efficiency of micropropagation by decreasing the quantity and quality of the tissue-cultured plantlets and