Hormone-free Murashige-Skoog Medium Research Articles

Клональное микроразмножение Astragalus gorodkovii Jurtz., Astragalus gorczakovskii L. Vassil. с использованием методов in vitro

Abstract. Microclonal propagation of rare plant species solves the problem of biodiversity conservation, because received explants can be introduced into natural conditions to maintain the stability of plant communities. The purpose of the research was to obtain in vitro cultures of rare species of plants from Fabaceae family: Astragalus gorodkovii and Astragalus gorczakovskii. Materials and methods: seeds of Astragalus gorodkovii were selected from the population of Komi Republic in 2004. Seeds of Astragalus gorczakovskii were collected in 2019 in Perm region and Sverdlovsk region. After sterilization and scarification, the seeds were placed on a hormone-free Murashige-Skoog medium. The resulting seedlings were placed on the medium in 4 variants of the concentration of phytohormones BAP and NAA, germinated at room temperature and 16-hour light day. Then the resulting explants were transplanted onto the medium in 9 variants of the concentrations of hormones. The results. 1.5–2 months can be considered as the optimal period for division and transplantation. Variants of the medium containing 0.5–1 mg/l of BAP and a smaller amount of NAA turned out to be the best for the reproduction of A. gorodkovii and A. gorczakovskii, because active branching of seedlings was observed without verification. A. gorodkovii showed the most active growth. The originality of this research is in the selection of the optimal medium composition for the germination of seeds of rare species A. gorodkovii and A. gorczakovskii. This biotechnological method is a tool for preserving the genetic diversity of plant communities of the Ural flora.

INDUCTION AND CONVERSION OF SOMATIC EMBRYOGENESIS ON THE ANTHER FILAMENT OF SPATHIPHYLLUM SCHOTT

A prerequisite for genetic manipulation, mutation breeding or ploidy manipulation of the ornamental crop Spathiphyllum is the availability of a system which allows a target cell to regenerate into a new plant. Induction of somatic embryos could offer a powerful tool to reach this goal. When placed on a Murashige sr Skoog medium supplemented with 10 mu M naphthaleneacetic acid (NAA) and 0.2 - 3 mu M thidiazuron (TDZ), anthers of different genotypes develop clumps of attached somatic embryos on the filament. The younger the anthers, the more sensitive their filament cells were for the induction of somatic embryogenesis. After six weeks, the somatic embryos were transferred to a Murashige & Skoog (MS) medium supplemented with 10 CIM benzylaminopurine (BA) + 0.02 mu M NAA to develop secondary somatic embryos. Another 6 weeks later, they were ready for conversion. The best conversion medium was a hormone-free MS medium. Addition of abscisic acid (ABA) had a negative effect. After a conversion period of 10 weeks, the normal looking plants were transferred to the greenhouse.

Exogenous Phytohormone-Independent Growth and Regeneration of Tobacco Plants Transgenic for the 6b Gene of Agrobacterium tumefaciens AKE10

The 6b gene of Agrobacterium tumefaciens AKE10 (AK-6b) induces crown gall tumors on certain plants but so far there have been no reports of the gene being able to induce tumors on culture medium. We cloned T-DNA segments containing the 6b gene but lacking the auxin and cytokinin biosynthesis genes from A. tumefaciens AKE10. Tobacco (Nicotiana tabacum) leaf discs infected with A. tumefaciens LBA4404 carrying the clones produced shooty calli on hormone-free Murashige-Skoog medium. The relevant T-DNA segment was integrated into plant DNA as determined by Southern hybridization. Some of these immature shoots spontaneously developed into mature shoots, of which several leaves displayed morphological abnormalities. When leaf discs of these mature plants were placed onto the same medium numerous shoots developed from the wounding sites, indicating that the transgenic plants possessed a high regenerative potential. Northern blot and reverse transcriptase-polymerase chain reaction analyses showed a large accumulation of the AK-6b transcripts in the shooty calli, but only a limited degree in mature plants, demonstrating that AK-6b expression is regulated in plants and essential for the early stages of regeneration. Cytokinin levels in the shooty calli were comparable to those in normal shoots, suggesting that shoot regeneration is not mediated by the modulation of cytokinin content.

Clonal micropropagation of Gentiana scabra bunge var. buergeri Maxim. and examination of the homogeneity concerning the gentiopicroside content.

When the axillary buds of Gentiana scabra BUNGE var. buergeri MAXIM. were cultured on Murashige-Skoog (MS)medium supplemented with a combination of gibberellin A3 (GA) and 6-benzylaminopurine (BAP) (1mg/l each) at 25°C under 16h light conditions for 60d, the direct multiple shoot formation (18.5 shoots per axillary bud) occurred. The MS medium containing Ga-BAP (2.5mg/l each) mostly stimulated the multiple shoot formation having approximately 71 shoots per tissue in the second subculture of the regenerated shoot. The hormone free MS medium stimulated root formation. These clonally propagated plants were transplanted to vermiculite. Quantitative analysis of gentiopicroside contained in the root of plantlets was carried out by high performance liquid chromatography using p-anisic acid as an internal standard. Obviously, the variation of the clonally propagated plants was smaller than that of the cultivated plants bred by morphological selection. From this system, 4.7×108 clonally propagated plants can be theoretically obtained from an axillary bud in a year.

Effects of capsule hardness on germination frequency of encapsulated somatic embryos of carrot

Somatic embryos of carrot were encapsulated in calcium alginate beads to provide artificial carrot seeds. Alginate capsules with a hardness of 0.2 to 0.5 kg/cm2 were found to be suitable for germination of encapsulated somatic embryos. The germination frequencies were more than 95%, when grown aseptically on polyester fiber supports loaded with hormone-free Murashige-Skoog medium.