Submitted to: Plant Cell Tissue and Organ Culture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/3/2004
Publication Date: 5/1/2004
Citation: Hofmann, N.E., Nelson, R.L., Korban, S.S. 2004. Influence of media components and PH on somatic embryo induction in three genotypes of soybean. Plant Cell Tissue and Organ Culture. 77:157-163. Interpretive Summary: One of the most important systems that facilitate the creation of transgenic plants and propagation of soybean cultures in the laboratory is the somatic embryo culture system. Multiple somatic embryos can be induced from an immature soybean seed and then can be used for transformation. These embryos can be regenerated into whole plants easier than single cells. To date the generation of somatic embryos has been inefficient. Our work showed that soybean varieties differed in both the percentage of immature seeds that produced somatic embryos but also in the number of embryos produced per immature seed. The hormone and sugar levels in the medium on which the immature seeds were grown affected the rate of embryogenesis and different varieties had different optimum levels for these additives. Selecting the right variety and matching the medium ingredients to the variety can greatly increase the efficiency of somatic embryogenesis. These results will of use to soybean scientists developing transgenic soybean plants or culturing soybean tissue in the laboratory.
Technical Abstract: The influence of media components on the initiation of somatic embryogenesis in three genotypes of soybean was investigated. The following genotypes were used: Iroquois, Macon, and Savoy. Media modifications included sucrose concentration, type and concentration of auxin at two pH levels, and pH level independently. Immature cotyledons were used as the source of explant. Cotyledons were placed on a medium containing MS salts, B5 vitamins, sucrose, and auxin. Gelrite (0.2%) was used as the solidifying agent. Sucrose concentrations of 1, 2, 3, 4.5, or 6% were used. The auxins used included 2,4-dichlorophenoxyacetic acid (2,4-D) and naphthaleneacetic acid (NAA) with each at concentrations of 45.2, 90.4, 135.7, 180.9, and 226.2 µM. The pH of each the media was adjusted to either 5.7 or 7.0 with 1N NaOH. In an additional experiment, the effect of the two pH levels, 5.7 and 7.0, was investigated independently. Overall, the frequency of somatic embryogenesis significantly varied among the different genotypes used in this study, with Iroquois showing the highest response. Frequency of somatic embryogenesis also varied in response to the different treatments used, including sucrose and auxin. The highest initiation (91.7%) and mean number of somatic embryos per responding explant (14.9) of Iroquois was observed in a medium containing 2% sucrose. The highest initiation (97.1%) and mean number of somatic embryos per responding explant (19.45) was observed in Iroquois on 135.7 µM 2,4-D and Macon on 135.7 µM 2,4-D, respectively, for the auxin by pH level experiment. No significant differences were observed among the two pH treatments used.