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A bioreactor was used to establish a scale-up system for somatic embryogenesis in `Scarlet' carrot (Daucus carota L.). At a cell density of 1–2 × 106 cells/ml, mature and germinating embryos could be observed within 4 to 5 weeks. As cell density exceeded 2 × 106 cells/ml, the culture turned darker yellow, and embryo development was inhibited. Cell densities below 106 cells/ml resulted in abnormal embryos. Bioreactor design had a critical impact on somatic embryogenesis due to various types and the strength of shear forces generated. In this study, an air-lift bioreactor was selected from three different types (spinner flask, screen column bioreactor, and air lift) because it resulted in the highest biomass production and somatic embryogenesis. Foaming was eliminated by preculture of embryogenic cells in flasks; cells were then sieved on a 60-μm polyester screen and thoroughly rinsed with distilled water before being transferred to the bioreactor. Such preculture for at least 10 days significantly increased the regeneration of somatic embryos. During somatic embryogenesis, dissolved O2 concentrations decreased to 33% of saturation, and then increased up to 80% when embryo development approached maturity and mature embryos germinated. Bioreactor-cultured embryos germinated with relatively short cotyledons and long roots, whereas flask-cultured embryos germinated with relatively long cotyledons and short roots.
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.