Micropropagation is an important technique for clonal mass propagation and a tool for in vitro studies. One of the first steps to overcome in this process is the establishment of new explants in vitro. ‘Delite’ rabbiteye blueberry was cultured in vitro with four cytokinins (zeatin (ZEA), 6-(γ-γ-dimethylallylamino)-purine (2iP), 6-benzylaminopurine (BAP), and kinetin (KIN)) at eight concentrations (0, 2.5, 5, 10, 20, 30, 40, and 50 µM). Additionally, nine combinations of nitrogen salts were tested, using Woody Plant Medium (WPM) and a modified WPM as the basic medium. ZEA and 2iP showed better responses, but ZEA was superior at lower (2.5 µM) concentrations (89.7% survival, 81.3% shoot formation, 1.3 shoots, 13.8 mm shoot length, 10.0 leaves). BAP and KIN showed very low responses. In the combinations of salts with modified WPM, no differences were observed. However, the original WPM with treatments of 0.5 × NH₄NO₃ and 1 × Ca(NO₃)₂, 0.5 × NH₄NO₃ and 0.5 × Ca(NO₃)₂, and the modified WPM alone showed the lowest rates of survival and shoot formation and the shortest shoot lengths. The highest shoot lengths were observed in treatments with the original WPM, 1.5 × NH₄NO₃ and 0.5 × Ca(NO₃)₂, and 1.5 × NH₄NO₃ and 1.5 × Ca(NO₃)₂. This initial study with ‘Delite’ can be the basis for further experiments with different combinations of salts, 2iP, and ZEA.

Blueberries are valued for their taste and their high nutritional benefits, including their antioxidant and anti-inflammatory properties. In vitro culturing is an alternative method for clonal propagation, and has been used in many biotechnological studies. Most blueberry research is concentrated on highbush and lowbush taxa (Vaccinium corymbosum and Vaccinium angustifolium respectively), with only limited investigations of rabbiteye cultivars (Vaccinium virgatum) that are more suitable for subtropical climates and regions with warmer winters as a result of climate change. There is therefore a need to determine in vitro protocols for that species and group of cultivars. We examined here adventitious shoot regeneration in the ‘Delite’ rabbiteye blueberry cultivar. Leaf explants were cultured in vitro in Woody Plant Medium (WPM), and the effects of different thidiazuron (TDZ) concentrations, the orientation of the leaf (adaxial or abaxial surface in contact with the medium), and two portions of the leaf segment (basal or apical) were examined. De novo shoot development was studied using light and scanning electron microscopy. All concentrations of TDZ used showed similar survival and regeneration rates; 0.5 μM TDZ showed high efficiency in regenerating adventitious shoots (100%, with 57 adventitious shoots/explant), as did the adaxial surface in contact with the medium using either the apical or the basal portion of the leaf (97% shoot regeneration, 47.5 adventitious shoots/explant). Anatomical analyses showed direct and indirect organogenesis. The shoots developed leaf primordia with stomata, trichomes, and well-developed vascular tissues, with further elongation and rooting of the plants. We therefore describe here a high-efficiency regeneration method through de novo shoot organogenesis using TDZ in foliar explants of rabbiteye blueberry, with direct and indirect organogenesis.

Rubber dandelion (Taraxacum kok-saghyz Rodin; TK) has received attention for its natural rubber content as a strategic biomaterial, and a promising, sustainable, and renewable alternative to synthetic rubber from fossil carbon sources. Extensive research on the domestication and rubber content of TK has demonstrated TK’s potential in industrial applications as a relevant natural rubber and latex-producing alternative crop. However, many aspects of its biology have been neglected in published studies. For example, floral development is still poorly characterized. TK inflorescences were studied by scanning electron microscopy. Nine stages of early inflorescence development are proposed, and floral micromorphology is detailed. Individual flower primordia development starts at the periphery and proceeds centripetally in the newly-formed inflorescence meristem. Floral organogenesis begins in the outermost flowers of the capitulum, with corolla ring and androecium formation. Following, pappus primordium—forming a ring around the base of the corolla tube—and gynoecium are observed. The transition from vegetative to inflorescence meristem was observed 21 days after germination. This description of inflorescence and flower development in TK sheds light on the complex process of flowering, pollination, and reproduction. This study will be useful for genetics, breeding, systematics, and development of agronomical practices for this new rubber-producing crop.

Blueberries have large amounts of antioxidant and anti-inflammatory compounds, playing an important role in improving health. In vitro culture is a possible method for vegetative propagation overcoming the problems of pathogen infection. Most studies on the in vitro culture of blueberries focus on highbush and lowbush cultivars. However, blueberry rabbiteye cultivars have lower chilling requirements and are more adapted to mild winter regions. Our objective was to develop a micropropagation protocol through axillary shoot growth, with reduced risks of somaclonal variation in ‘Delite’ rabbiteye blueberry. In vitro establishment was tested with single-node segments. The most promising results were using 2.5 µM zeatin. Multiplication through axillary shoot growth, starting with two-node stem segments were more successful in the concentration of 2.5 µM zeatin (70% of explants with axillary shoot growth). In vitro and ex vitro rooting with acclimatization were compared. In vitro rooting was achieved with immersion in 500 mg L⁻¹ IBA (indole-3-butyric acid). Different substrates and mineral salts were also compared in ex vitro rooting. The results in vermiculite with WPM mineral salts were superior (68% rooting). In conclusion, this study provides techniques for micropropagation through axillary shoots of ‘Delite’ rabbiteye blueberry concerning establishment, multiplication, rooting, and acclimatization of plants.