To establish a mass micropropagation procedure for Cephalotus follicularis, the effects of varying the strengths of solid Murashige and Skoog (MS) medium were investigated using subcultured shoot explants. After a 60-day primary culture from root mass, the regenerated shoot explants were subcultured every 60 days in solid MS medium. To facilitate shoot proliferation, liquid MS medium was applied with or without exogenous auxin and cytokinin. Our results demonstrate that shoot proliferation and survival of C. follicularis is most effective in modified MS (MMS) medium containing one-fifth or one-tenth strength macronutrients and full-strength micronutrients. Successful shoot proliferation and development of C. follicularis explants were obtained in one-fifth or one-tenth modified liquid MS medium without auxin and cytokinin or with addition of 5 μM indole 3-acetic acid/1 μM N6-benzyladenine for 45 days. The liquid medium consistently produced more explants than the solid medium and shortened the culturing time. Plantlets cultured in hormone-free one-fifth MMS medium developed greater root systems. Using the liquid culture we established, vigorous plants with extensive roots were obtained within 4 months. Plant survival in the greenhouse reached 100%.
Chia-Yun Ko, Tsai-Yun Lin, Chin-Wen Ho, and Jei-Fu Shaw
Sandy Lin, Hsiao-Ching Lee, Wen-Huei Chen, Chi-Chang Chen, Yen-Yu Kao, Yan-Ming Fu, Yao-Huang Chen, and Tsai-Yun Lin
Nuclear DNA contents were estimated by flow cytometry in 18 Phalaenopsis Blume species and Doritis pulcherrima Lindl. DNA amounts differed 6.07-fold, from 2.74 pg/diploid nuclear DNA content (2C) in P. sanderiana Rchb.f. to 16.61 pg/2C in P. parishii Rchb.f. Nuclear DNA contents of P. aphrodite Rchb.f. clones, W01-38 (2n = 2x = 38), W01-41 (2n = 3x = 57), and W01-22 (2n = 4x = 76), displayed a linear relationship with their chromosome numbers, indicating the accuracy of flow cytometry. Our results also suggest that the 2C-values of the Phalaenopsis sp. correlate with their chromosome sizes. The comparative analyses of DNA contents may provide information to molecular geneticists and systematists for genome analysis in Phalaenopsis. Endoreduplication was found in various tissues of P. equestris at different levels. The highest degree of endoreduplication in P. equestris was detected in leaves.