The orange color of tiger lily (Lolium lancifolium ‘Splendens’) flowers is due, primarily, to the accumulation of two κ-xanthophylls, capsanthin and capsorubin. An enzyme, known as capsanthin-capsorubin synthase (CCS), catalyzes the conversion of antheraxanthin and violaxanthin into capsanthin and capsorubin, respectively. We cloned the gene for capsanthin-capsorubin synthase (Llccs) from flower tepals of L. lancifolium by the rapid amplification of cDNA ends (RACE) with a heterologous non-degenerate primer that was based on the sequence of a gene for lycopene β-cyclase (lcyB). The full-length cDNA of Llccs was 1,785 bp long and contained an open reading frame of 1,425 bp that encoded a polypeptide of 474 amino acids with a predicted N-terminal plastid-targeting sequence. Analysis by reverse transcription–PCR (RT–PCR) revealed that expression of Llccs was spatially and temporally regulated, with expression in flower buds and flowers of L. lancifolium but not in vegetative tissues. Stable overexpression of the Llccs gene in callus tissue of Iris germanica, which accumulates several xanthophylls including violaxanthin, the precursor of capsorubin, resulted in transgenic callus whose color had changed from its normal yellow to red-orange. This novel red-orange coloration was due to the accumulation of two non-native κ-xanthophylls, capsanthin and capsorubin, as confirmed by HPLC and ultraperformance liquid chromatography–tandem mass spectrometry (UPLC-MS/MS) analysis with authentic standards. Cloning of the Llccs gene should advance our understanding of the molecular and genetic mechanisms of the biosynthesis of κ-carotenoids in general and in the genus Lilium in particular, and will facilitate transgenic alterations of the colors of flowers and fruits of many plant species.

Efficient protocols, safe from somaclonal variation, were developed for regeneration of Iris sibirica plants via organogenesis and somatic embryogenesis from leaf-base explants cultivated on Murashige and Skoog media supplemented with thidiazuron (TDZ, 1.0mg/l) or 2,4-dichlorophenoxyacetic acid (2,4-D, 1.0mg/l). The morphogenic response and callus formation efficiency differed significantly between 2,4-D (80.9%) and TDZ (67%) morphogenesis induction treatments. TDZ induced only organogenic calli, while calli obtained with 2,4-D were composed of three types differing in color and consistency: white, friable — embryogenic calli (4.5%, 3.8mg/explant), green, compact — organogenic calli (12.4%, 48.4mg/explants) and yellow — non-regenerative calli (77.3%, 254.4mg/explant). The cultivation of embryogenic calli on medium with 2,4-D and Kinetin resulted in further development of somatic embryos (54embryos/g of calli) which germinated with a frequency of 62% after being transferred to a medium without plant growth regulators. Stable shoot cultures were established by transferring organogenic calli with shoot primordia to media with 0.1mg/l α-naphthaleneacetic acid (NAA) and 1.0mg/l 6-benzylaminopurine (BA), while further cultivation on media of the same composition (TDZ or 2,4-D) resulted in the reduced growth and rhizogenesis, respectively. The TDZ induction treatment resulted in higher number of shoots per explant (7.9) than the 2,4-D treatment (4.3). After successful rooting and ex vitro acclimatization, plants were grown in the field and flowered to seed production. Flow cytometry, chromosome counting and random amplification of polymorphic DNA (RAPD) analysis indicated no evidence of genetic variation in plants regenerated via somatic embryogenesis or organogenesis. The results suggest that established protocols are safe for use in genetic transformation procedures or large-scale production of true-to-type I. sibirica plants

In ornamental geophytes, conventional vegetative propagation is not economically feasible due to very slow development and ineffective methods. It can take several years until a new plant is formed and commercial profitability is achieved. Therefore, micropropagation techniques have been developed to increase the multiplication rate and thus shorten the multiplication and regeneration period. The majority of these techniques rely on the formation of new bulbs and their sprouting. Dormancy is one of the main limiting factors to speed up multiplication in vitro. Bulbous species have a period of bulb dormancy which enables them to survive unfavorable natural conditions. Bulbs grown in vitro also exhibit dormancy, which has to be overcome in order to allow sprouting of bulbs in the next vegetation period. During the period of dormancy, numerous physiological processes occur, many of which have not been elucidated yet. Understanding the process of dormancy will allow us to speed up and improve breeding of geophytes and thereby achieve economic profitability, which is very important for horticulture. This review focuses on recent findings in the area of bulb dormancy initiation and release in fritillaries, with particular emphasis on the effect of plant growth regulators and low-temperature pretreatment on dormancy release in relation to induction of antioxidative enzymes’ activity in vitro.

The activities and isoenzyme profiles of superoxide dismutase (SOD) in in vitro Fritillaria meleagris bulbs in response to cold treatment (4?C) were investigated. Differences in SOD activity and isoenzyme profiles in bulbs under standard growth conditions, six weeks chilling, as well as seven days after the completion of cold treatment are presented. SOD activity initially decreased but then rapidly increased seven days after cold treatment. Four isoforms of SOD are active under standard and chilling conditions, while three isoforms are presented 7 days after cold treatment. Native gel electrophoresis indicated the presence of mitochondrial and chloroplast localized SODs. .