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Ronald W. Moore, P.E. Read, and T.P. Riordan

Stolon nodal segments of Buchloe dactyloides (Nutt.) Engelm. were removed from greenhouse grown plants and placed on Gamborg's B5 medium in order to determine nodal position and 2,4-D level required to give maximum callus initiation. 2,4-D levels used were 5uM, 16uM, 35uM, and 50uM. Six nodal segments were grouped according to position on the stolon, from the most recent node (node one) to the basal node (node 6). It was concluded that node 4 gave statistically greater callus mass than nodes 1, 2, 3, 5, and 6. Increasing levels of 2,4-D suppressed callus initiation, with maximum response occurring at 5uM 2,4-D.

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Hany M. El-Naggar, Paul E. Read, and Susan L. Cuppett

Rosemary Rosmarinus officinalis is a member of the Lamiaceae. Rosmarinic acid (RA) is a very strong antioxidant produced in the chloroplast, and used to protect plant tissues against oxidative stress. A number of investigations showed that the sucrose concentration in the callus growing medium greatly influenced the production of secondary metabolites of the phenylpropanoid pathway such as RA. The aim of this study was to test the effect of elevated sucrose concentrations (2%, 3%, 4%, 5%, and 6% sucrose) and the effect of light and dark treatments on the production of RA in the callus of five different genotypes. The genotypes were Majorca, Rosmarinus officinalis, Pine Scented, Madeline Hill, and APR. It was found that the dark treatment produces more RA than the light treatment in all genotypes, and in all sucrose concentrations. The RA concentration increased with increasing the sucrose concentration from 2%—reaching the highest concentration at 4% and 5% in most genotypes. The RA concentration declined again at 6% sucrose in all genotypes. We concluded that for the extraction of RA from rosemary callus it is preferred to be produced in the dark—this will save energy and will produce more RA than the light treatment. Also it is preferred to use sucrose concentration at 4% for genotypes Rosmarinus officinalis, Pine Scented, and APR; and 3% sucrose for genotype Madeline Hill in the dark condition. While for the light condition, it is preferred to use 5% sucrose with genotypes Majorca, Rosmarinus officinalis, Pine Scented, and Madeline Hill; and 4% sucrose for genotype APR.

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M. Koch, Z. Tanami, and R. Salomon

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F. Mark Schiavone and M.E. Wisniewski

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J.M. Al-Khayri, F.H. Huang, T.E. Morelock, and T.A. Busharar

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Jameel M. Al-Khayri, Feng H. Huang, Teddy E. Morelock, and Forrest E. Lane

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Karen G. Caires, Carol A. Bobisud, Susan P. Martin, and Terry T. Sekioka

Watercress petioles were planted on Murashige and Skoog media containing 30 g/l sucrose and 8.5 g/l agar, as well as concentrations of 10 and 20 uM benzylaminopurine (BAP) in combination with 5 and 25 uM indoleacetic acid (IAA) or 5 and 25 uM naphthaleneacetic acid (NAA). Calli were transferred to the same media or to media with 5 uM IAA and 10 uM BAP. Transfer to media with 5 uM IAA and 10 uM BAP resulted in an increased percentage of explants with shoots in the NAA plus BAP treatments while increasing the number of shoots per explant in the IAA plus BAP treatments. The greatest number of shoots per explant were obtained when explants were grown on media with 25 uM IAA and 20 uM BAP and then transferred to media with 5 uM IAA and 10 uM BAP. Thirty percent of the explants rooted on media with 25 uM NAA and 20 uM BAP followed bv transfer to 5 uM IAA and 10 uM BAP.

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Shanqiang Ke and Chiwon W. Lee

Coleoptile tissues from dark-germinated seedlings of Kentucky bluegrass (Poa pratensis L.) cv. Touchdown were excised and cultured on MS medium supplemented with 1.5-2.5 mg/liter picloram plus 0.2 mg/liter benzyladenine (BA) or with 4 mg/liter 2,4-D. Embryogenic calli were formed on media containing 1.5 mg/liter picloram plus 2.5 mg/liter 2,4-D in the dark. When these embryogenic calli were subcultured on MS medium containing either 0.15-0.3 mg/liter picloram or 0.2-0.5 mg/liter 2,4-D in a 16-h day/8-h night photoperiod, 10.5% of the cultures regenerated shoots. Pretreatment of cultures in the dark for 2 weeks prior to light exposure slightly increased the plant regeneration efficiency to 15.5%. Pigmentation of the regenerants varied with a ratio of 8.5 completely green: 2.5 green plus albino: 1 completely albino plants. The shoots were multiplied in the medium containing 0.5 mg/liter BA plus either 0.2 mg/liter picloram or 0.1 mg/liter indoleacetic acid (IAA). Over 90% cultures in the shoot proliferation medium produced roots after 4 weeks.

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María de Lourdes Miranda-Ham, Lizbeth A. Castro-Concha, Elide Avilés-Berzunza, and Gregorio Godoy-Hernández

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Mihoko Tamura, Ryutaro Tao, and Akira Sugiura