Improvement of in vitro embryo maturation, plantlet regeneration and transformation efficiency from alfalfa (Medicago sativa L.) somatic embryos using Cuscuta campestris extract

Organic and inorganic elicitors enhance in vitro regeneration of Rosa canina

Background

Rosa canina is one of the most popular rose species which is widely used as the rootstock for the propagation of rose cultivars. The purpose of the present study is to improve the in vitro propagation efficiency of this valuable plant species using various growth stimulants in a proliferation medium. In this study, in vitro-derived axillary buds of R. canina were inoculated in Vander Salm (VS) medium supplemented with varying levels of organic or inorganic elicitors including casein hydrolysate (200, 400, and 600 mg/l), glutamic acid (2, 4, 8, and 12 mg/l), proline (500, 1000, 1500, and 2000 mg/l), and silver nitrate (25, 50, 75, and 100 mg/l), separately. Benzyl amino purine (BAP) as well as naphthalin acetic acid (NAA) were added to all media at a constant rate to promote shoot proliferation.

Results

The results indicated that the supplementation of casein hydrolysate to the VS medium markedly stimulated shoot regeneration by 173% in comparison to control. Shoot proliferation was also positively influenced by glutamic acid at all levels, however, at a lesser extent compared to casein hydrolysate. Silver nitrate at 100 mg/l induced the longest shoots (2.52 ± 0.248 cm) and maximum leaf number (8.90 ± 0.276) among all treatments. Although it did not encourage efficient shoot regeneration, the highest quality shoots with maximum growth vigor were observed in this treatment.

Conclusion

In this study, the promising role of casein hydrolysate in combination with plant growth regulators has been emphasized for the improved efficiency of R. canina regeneration protocol. Moreover, the addition of silver nitrate to the culture medium seems vital for enhancing the quality of regenerated shoots. The results of this study could be beneficial either for the further pharmaceutical or biochemical investigations of R. canina or commercial purposes for mass propagation of this specimen.

Tissue culture, genetic transformation, interaction with beneficial microbes, and modern bio-imaging techniques in alfalfa research

Current research needs to be more focused on agronomical plants to effectively utilize the knowledge obtained from model plant species. Efforts to improve legumes have long employed common breeding tools. Recently, biotechnological approaches facilitated the development of improved legumes with new traits, allowing them to withstand climatic changes and biotic stress. Owing to its multiple uses and profits, alfalfa (Medicago sativa L.) has become a prominent forage crop worldwide. This review provides a comprehensive research summary of tissue culture-based genetic transformation methods, which could be exploited for the development of transgenic alfalfa with agronomically desirable traits. Moreover, advanced bio-imaging approaches, including cutting-edge microscopy and phenotyping, are outlined here. Finally, characterization and the employment of beneficial microbes should help to produce biotechnologically improved and sustainable alfalfa cultivars.

Long-Term Maintainable Somatic Embryogenesis System in Alfalfa (Medicago sativa) Using Leaf Explants: Embryogenic Sustainability Approach

Alfalfa (Medicago sativa) is one of the most important forage legume crops because of its mass production and high feeding value. It originated in Asia and is one of the most ancient plants cultivated throughout the world as a fodder. Despite the well-studied somatic embryogenesis of alfalfa, there is a lack of a long-term maintainable somatic embryogenic system. Every time an embryogenic callus culture must be started from new explants, which is laborious, costly and time consuming. In addition to this, endogenous microorganisms present in ex vitro explants of alfalfa can often cause contamination, reducing the efficiency of callus culture. An attempt was made to establish long-term continuous somatic embryogenesis system in alfalfa using cultivar Regen-SY. Nine somatic embryogenesis pathways were studied and evaluated for embryo yield, plant conversion rate and embryogenic sustainability. Somatic embryos passed through the same stages (globular, heart-shaped, torpedo and cotyledonary) as characteristic of the zygotic embryo and secondary somatic embryogenesis was also observed. B5H-B5 system showed the highest embryo yield and plant conversion rate whereas SH4K-BOi2Y system demonstrated the highest embryogenic sustainability and maintained the embryogenic potential even after six subculture cycles. Scanning electron microscopy was applied to study the morphology of the somatic embryos and secondary somatic embryogenesis. Therefore, long-term maintainable somatic embryogenesis system protocol was developed through this study, which will help to enhance and accelerate the alfalfa biotechnology research.