Sorghum bicolor is a recalcitrant species for tissue culture regeneration and genetic transformation. Browning of explants is one of the factors limiting organ and tissue cultures. To overcome this, callus tissue was initiated from the shoot tips of in vitro germinating seeds (S. bicolor cv. Róna 1), and then cultured on modified MS media (Murashige and Skoog in Physiol Plant 15:473-497, 1962). In the first experiment, we tested callus induction on several media supplemented with casein hydrolysate, polyvinylpyrrolidone, honey, and sucrose. The best callus induction was recorded for the medium with honey and sucrose (80.0%) and for control medium (79.8%). Shoot regeneration was tested on the MS medium with 6-benzylaminopurine (BAP) supplemented with honey and sucrose at a 1:1 ratio (by weight) or with sucrose only. The highest percentage of calluses regenerating shoots was noted for those induced on the medium with sucrose and honey-approx. four times higher when compared to the control. Rooted plantlets were acclimatized with a 92% survival rate. In the second experiment, we analyzed culture responses to various ways of honey application to the induction media: honey (autoclaved or filtered) in presence or absence of sucrose. Supplementation of the medium with fructose, glucose, and maltose at a proportion typical for honey was also investigated. The explant and callus survival rates were similar to those of the honey-sucrose combination in the first experiment. Only presence of both sucrose and honey in the induction medium improved the total regeneration rate to 37.9% over the control (18.8%). Sucrose and honey appear to act synergistically for shoot regeneration in callus cultures of sorghum.

Summary Introduction: The technological advancements in the production of synthetic seeds are critical for the preservation of valuable genotypes of many herbal plants, including Salvia officinalis – sage. Objective: The aim of this study was the production, storage and conversion of artificial sage seeds. The technology of synthetic seeds is placing explants capable of regeneration into plants in a protective casing. Methods: Apical and axillary buds were encapsulated with 1.2% sodium alginate solution, and then dripped in 200 mM CaCl2 solution. Artificial seeds were stored at 4°C for 30 days and then converted on MS medium containing 0.3 mg/l of BAP. Results: The synthetic seeds technology made it possible to obtain a high level of seeds conversion into plants using apical buds (85.0%), and slightly lower in the case of side buds (62.5%). Conclusion: The fully developed technology of synthetic seeds made it possible to obtain a high level of plant viability, which may prove useful for the storage of valuable genotypes of sage.

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