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  • Author or Editor: Kee Yoeup Paek x
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This study was designed to assess the general limitations of somatic hybridization as one of the key technologies for genetic manipulation in plants. The limits of somatic hybridization against different taxonomic backgrounds, intraspecific to interfamilial, were also assessed. Protoplast culture studies provided essential information relating to the species cultural and morphogenetic capacity. several #elect Ion strategies for the recovery of somatic hybrid colonies/plants were developed and assessed using various combinations of protoplast sources and species in the genera Petunia, Nicotiana, Salpiglossis and Chrysanthemum. Morphological, cytological and biochemical analyses were performed to confirm the hybridity of plants or cell lines recovered following protoplasm fusion (using 4-5 methods) and selection.

The somatic hybrid callus/plants were obtained at intraspecific to interfamilial levels by complementation to chlorophyll proficiency, together with media selection or complementation of nitrate reductase deficient mutants as follows; P. Hybrida var. Monsanto (+) P. hybrida cv. Blue Lace (intraspecific), P. hybrida var. Monsanto (+) P. inflata and P. parviflora (interspecific), P. parviflora (+) N. tabacum (intergeneric), S. sinuata (+) P. hybrida var. Monsanto, P. parodii and N. tabacum (intertribal), and C. morifolium (+) S. sinuata.

From this study, it appeared that there were no taxonomic limits to the production and proliferation of somatic hybrid cell lines. However, obtaining morphologically normal hybrid plants met with limited success as the taxonomic relationships became more distant. The regeneration capacity of somatic hybrids seemed to be controlled by both parental species. Somatic incompatibility mechanism was also shown to operate on chromosome elimination. Such chromosome elimination may well be advantageous in plant improvement.

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This experiment was carried out to determine correct applications of GA3 for the production of cut flowers of Zantedeschia albomaculata cv. Black Magic in highlands. Tubers were treated with GA3 in concentrations of 0, 100, and 200 mg·L-1. ABA contents in the tubers and roots were twice as high (20∼25 pmol/mL) in the control as in GA3-treated tubers and roots. ABA content in roots increased with increasing GA3 concentration. Growth of the calla was investigated according to the tuber hardness (3.3, 6.0 kg·cm-2), GA3 concentrations (0, 100, 200 mg·L-1), and GA3 treatment duration (24 h, 12 h, and 30 min before planting). Tubers with higher tuber hardness were strong against soft rot, regardless of the GA3 concentrations and treatment durations. Tubers with lower tuber hardness showed over 90% soft rot occurrence when treated with 200 mg·L-1 GA3 for 24 h before planting. However, soft rot did not occur when treatment with 200 mg·L-1 GA3 was used for 12 h before planting.

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Paphiopedilum spp. is one of the most commercially popular orchids because of its variety of shapes, sizes, and colors. However, it is at risk for extinction because of its exploitation. Regeneration of orchid plants using internode segments is extremely difficult. In this study, young P. callosum plants (1.5 cm) were exposed to eight dark–light cycles (14 days of dark and 1 day of light) for stem elongation to increase the number of nodes to obtain internode tissues. After 75 days of culture, the highest callogenesis (31.25%) was achieved when internode tissue was cultured on liquid Schenk and Hildebrandt (SH) medium containing 30 g·L−1 sucrose, 1.0 mg·L−1 Thidiazuron (TDZ), 1.0 mg·L−1 2,4-Dichlorophenoxyacetic acid (2,4-D), and cotton wool as the support matrix. The optimal media for induction of protocorm-like bodies (PLBs) were the same compositions as previously mentioned and were supplemented with 9 g·L−1 Bacto agar as the gelling agent. PLB clumps (5–6 PLBs/clump) produced the best shoots on medium containing 0.5 mg·L−1 α-Naphthaleneacetic acid (NAA) and 0.3 mg·L−1 TDZ. Among the organic substances tested, 200 g·L−1 potato homogenate (PH) added to Hyponex N016 medium supplemented with 1.0 mg·L−1 NAA, 30 g·L−1 sucrose, 170 mg·L−1 NaH2PO4, 1.0 g·L−1 peptone, and 9 g·L−1 Bacto agar resulted in the best rooting. The rooted plantlets with four to five leaves were acclimatized and had a 100% survival rate. The method presented in this research provides a strategy for the development of highly effective propagation of Paphiopedilum species using ex vitro explants for both conservation and horticultural purposes.

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