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  • Author or Editor: Piyada A. Tantasawat x
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To reveal the applicability of sequence-related amplified polymorphism (SRAP) and target region amplification polymorphism (TRAP) markers to mutant genotyping and marker identification for resistance to black rot (Phytophthora palmivora) in orchids (Dendrobium sp. ‘Earsakul’), we fingerprinted four nonmutagenized controls and 12 black rot-resistant mutants obtained with in vitro sodium azide (NaN3) and ethyl methanesulfonate (EMS) mutagenesis and in vitro selection using culture filtrate of P. palmivora. Each of the 20 SRAP and TRAP primer combinations yielded 375 and 384 scorable DNA bands, respectively, of which 94 (24.42%) and 88 (22.91%) were polymorphic, respectively. Mantel’s test cophenetic correlation coefficients of SRAP, TRAP, and SRAP/TRAP were 0.750, 0.921, and 0.861, respectively, indicating the efficiency of these markers, especially TRAP and SRAP/TRAP, for Dendrobium sp. ‘Earsakul’ mutant characterization. Moreover, the correlations between the matrices of cophenetic correlation values for the dendrograms of SRAP with TRAP, SRAP with SRAP/TRAP, and TRAP with SRAP/TRAP were 0.399, 0.566, and 0.793, respectively, and the dendrograms based on SRAP vs. TRAP and SRAP vs. SRAP/TRAP, with lower correlations, had more variations, i.e., the number of clusters, the members of clusters, and the placement of the materials, than the ones based on TRAP vs. SRAP/TRAP. Among the three dendrograms, all nonmutagenized controls were clustered together, whereas all the highly resistant and the most resistant mutants were distributed separately as individuals. Interestingly, the four SRAP and TRAP markers were significantly associated with black rot resistance. Overall, our results will be useful for facilitating future Dendrobium sp. ‘Earsakul’ breeding programs.

Open Access

The effects of culture media on growth and proliferation of ‘Earsakul’ dendrobium (Dendrobium) protocorm-like bodies (PLBs) were evaluated in a two-step culture. After culturing on each of the four first step media for 4 months and on each of the four second step media for 4 months, the greatest total PLB fresh weight, increase in number of PLBs and growth rates were obtained when using Vacin and Went medium 1 (VW1) in both culture steps compared with those in 15 other medium combinations. Starting from 0.5 g of PLBs, culturing on VW1 for 8 months achieved a total of 415.25 g of PLBs, a multiplication rate of 830-fold. The supplementation of tomato (Solanum lycopersicum) and substitution of ‘Hom Thong’ banana [Musa acuminata (AAA group)] with ‘Khai’ banana [M. acuminata (AA group)] in this new medium promoted growth and proliferation of dendrobium PLBs 2.4-fold over the control medium, suggesting its usefulness in commercial micropropagation.

Free access