Key phenological events in globe artichoke (Cynara cardunculus var.scolymus) development

A priority for the field vegetable grower is to be able to schedule a regular supply of product throughout the growing season. This requires a predictive framework, based on the identification of key developmental events of the crop, and an understanding of how genotypic and environmental factors interact to determine plant development. Four globe artichoke (Cynara cardunculus var. scolymus) cultivars, representing the existing phenological range, were grown in a field experiment, and a range of environmental conditions was imposed by varying both the timing of the first irrigation (which determines the initiation of regrowth) and by repeating the experiment across two locations and 2 years. The timing of the appearance of the main stem capitulum was sensitive to both the growing environment and the cultivar. These differences persisted till flowering and were correlated with final leaf number. As the plant developed, the phyllochron decreased, resulting in three values of phyllochron, each of which was responsive to genotype, and hardly to environment. The timing of the first change in phyllochron was associated with the final leaf number and the appearance of the capitulum. For all the cultivars, the rate of development fell and the final leaf number increased as the length of the photoperiod increased. The later flowering cultivars shared a similar vernalisation requirement, but ‘Spinoso sardo’ did not require a cold period to flower. Leaf length reached a peak before the beginning of stem elongation, and maximum leaf length was correlated with final leaf number. The sensitiveness of the phyllochron to the genotype, and of the number of leaves and the timing of the appearance of the capitulum to both genotype and environment makes them suitable as variables in developmental models. The importance of the final number of leaves is not only because of its phenological significance, but also because of its effect on the ability of the canopy to intercept radiation.     

Insect pollinators improve seed production in globe artichoke (Cynara cardunculus var. scolymus)

The role of many insect species in crop pollination has been widely studied. The use of entomophilous pollination, commonly adopted for other crops, may be of key importance in order to improve seed yields in seed-propagated globe artichoke (Cynara cardunculus var. scolymus) cultivars. In this regard, in a 2-year field experiment, the role of two honeybees (Apis mellifera ligustica and A. mellifera siciliana) and one bumblebee (Bombus terrestris) was evaluated on the seed production of two globe artichoke cultivars in caged-protected environments. Overall, the number and weight of seeds plant⁻¹ and head⁻¹, 1,000 seed weight and fruit setting were higher in caged plants with imposed pollination than open field plants. The pollination efficiency was both insect and cultivar dependent. Both honeybee species performed better on the Mediterranean cultivar ‘Violetto di Sicilia’, while the bumblebee performed better on the Brazilian cultivar ‘NP4’. These results could be very useful to modernise the agronomic management of globe artichoke and reduce the costs of cultivation. In addition, such knowledge can be used to improve the seed production in globe artichoke seed-propagated cultivars and cardoon. This will benefit the bioenergy, nutraceutical, cosmetic and ornamental applications.     

Effectiveness of mycorrhizal fungi on globe artichoke (Cynara cardunculus L. var. scolymus) micropropagation

The effectiveness of two arbuscular mycorrhizal (AM) fungal isolates (Glomus intraradices and Glomus viscosum) in sustaining plant growth and the physiological activities of the micropropagated globe artichoke (Cynara cardunculus L. var. scolymus (L.) Fiori) were investigated during acclimatization and 90 days after plant establishment. All the mycorrhizal microplants survived transplant shock thus confirming the positive role of AM fungi colonization on ex vitro establishment. The growth increased in mycorrhizal plants, especially in plants inoculated with Glomus viscosum. Mycorrhizal plantlets showed higher stomatal conductance, which is probably necessary to supply the carbon needs of fungal symbionts. The SPAD (soil plant analysis development) data could be useful for plant management as a predictor for tissue nitrogen levels. The higher SPAD values in mycorrhizal plants are strictly related to a higher photosynthetic potential, and consequently to their better nitrogen nutrient status due to the symbiotic relationship. Regardless of the mycorrhizal performance in the host–fungus combination, the most efficient fungus for the artichoke microplants was Glomus viscosum.     

Isolation of microsatellite loci in artichoke (Cynara cardunculus L. var. scolymus)

We report the development of nine microsatellite markers in globe artichoke (Cynara cardunculus L. var. scolymus). Four markers were obtained from sequences available in GenBank and five were isolated using a biotin/streptavidin capture technique for (CA)_n and (CT)_n motifs directly from artichoke genomic DNA. Polymorphism was explored in 15 artichoke accessions that represent the genetic variation within cultivated varietal types. Inter‐specific amplification was tested using cultivated cardoon (C. cardunculus L. var. altilis DC.) and wild cardoon (C. cardunculus L. var. sylvestris Lam.). Primers and conditions for polymerase chain reaction (PCR) amplification of detected loci are described.     

Protective properties of artichoke (Cynara scolymus) against oxidative stress induced in cultured endothelial cells and monocytes

It is currently believed that oxidative stress and inflammation play a significant role in atherogenesis. Artichoke extract exhibits hypolipemic properties and contains numerous active substances with antioxidant properties in vitro. We have studied the influence of aqueous and ethanolic extracts from artichoke on intracellular oxidative stress stimulated by inflammatory mediators (TNFalpha and LPS) and ox-LDL in endothelial cells and monocytes. Oxidative stress which reflects the intracellular production of reactive oxygen species (ROS) was followed by measuring the oxidation of 2', 7'-dichlorofluorescin (DCFH) to 2', 7'-dichlorofluorescein (DCF). Agueous and ethanolic extracts from artichoke were found to inhibit basal and stimulated ROS production in endothelial cells and monocytes in dose dependent manner. In endothelial cells, the ethanolic extract (50 microg/ml) reduced ox-LDL-induced intracellular ROS production by 60% (p<0,001) while aqueous extract (50 microg/ml) by 43% (p<0,01). The ethanolic extract (50 microg/ml) reduced ox-LDL-induced intracellular ROS production in monocytes by 76% (p<0,01). Effective concentrations (25-100 microg/ml) were well below the cytotoxic levels of the extracts which started at 1 mg/ml as assessed by LDH leakage and trypan blue exclusion. Penetration of some active substances into the cells was necessary for inhibition to take place as juged from the effect of preincubation time. These results demonstrate that artichoke extracts have marked protective properties against oxidative stress induced by inflammatory mediators and ox-LDL in cultured endothelial cells and monocytes.     

Molecular properties and prebiotic effect of inulin obtained from artichoke (Cynara scolymus L.)

A high molecular weight inulin has been prepared from artichoke (Cynara scolymus L.) agroindustrial wastes using environmentally benign aqueous extraction procedures. Physico-chemical analysis of the properties of artichoke inulin was carried out. Its average degree of polymerization was 46, which is higher than for Jerusalem artichoke, chicory, and dahlia inulins. GC-MS confirmed that the main constituent monosaccharide in artichoke inulin was fructose and its degradation by inulinase indicated that it contained the expected beta-2,1-fructan bonds. The FT-IR spectrum was identical to that of chicory inulin. These data indicate that artichoke inulin will be suitable for use in a wide range of food applications. The health-promoting prebiotic effects of artichoke inulin were demonstrated in an extensive microbiological study showing a long lasting bifidogenic effect on Bifidobacterium bifidum ATCC 29521 cultures and also in mixed cultures of colonic bacteria.     

Effects of artichoke (Cynara scolymus) leaf and bloom head extracts on chemically induced DNA lesions in Drosophila melanogaster

The genotoxicity of bloom head (BHE) and leaf (LE) extracts from artichoke (Cynara scolymus L.), and their ability to modulate the mutagenicity and recombinogenicity of two alkylating agents (ethyl methanesulfonate – EMS and mitomycin C – MMC) and the intercalating agent bleomycin (BLM), were examined using the somatic mutation and recombination test (SMART) in Drosophila melanogaster. Neither the mutagenicity nor the recombinogenicity of BLM or MMC was modified by co- or post-treatment with BHE or LE. In contrast, co-treatment with BHE significantly enhanced the EMS-induced genotoxicity involving mutagenic and/or recombinant events. Co-treatment with LE did not alter the genotoxicity of EMS whereas post-treatment with the highest dose of LE significantly increased this genotoxicity. This enhancement included a synergistic increase restricted to somatic recombination. These results show that artichoke extracts promote homologous recombination in proliferative cells of D. melanogaster.     

Stimulation of putrescine biosynthesis via the ornithine decarboxylase pathway by gibberellic acid in the in vitro rooting of globe artichoke (Cynara scolymus)

Rooting and growth of globe artichoke (Cynarascolymus) cuttings were improved by supplementing the rooting mediumwith 10 M gibberellic acid(GA₃). Exogenous putrescine (Put) (0.5mM) raised the percentage of rooting to thesame level as GA₃, but decreased the number of roots per plant.Addition of Put to GA₃ produced the same effects on growthparametersand rooting percentage as Put alone. Changes in endogenous contents of freepolyamines (PAs) were determined in plants cultured 4 weeks in a rootingmedium.Whatever the treatments, rooting caused a large decrease in Put, the largelypredominant PA, in the leaves. GA₃ increased the free Put content ofthe leaves and roots. DL--difluoromethylarginine (DFMA), which inhibitsarginine decarboxylase (ADC), did not affect rooting while Put content wasdecreased by 12–15%. DFMA changed neither GA₃ effectsnor those from DFMO when used in combination. An inhibitor of ornithinedecarboxylase (ODC), DL--difluoromethylornithine (DFMO), inhibited leafgrowth as well as rooting and decreased the Put content; these effects werepartially reversed by addition of Put. GA₃ combined with DFMO didnotalleviate the inhibitory effects of DFMO. The GA₃ treatment caused aclear stimulation of ODC activity in the leaves; it also stimulated¹⁴C-putrescine uptake (2.8-fold) by leaves and its translocationtowards roots. These results indicate that the ODC pathway mediates thehormone-induced rooting response in globe artichoke. Moreover, a release of Putfrom its conjugates could contribute to the increase of free-Put levels in theroots under GA₃ treatment. Thus, Put can be considered to be a goodmarker of rhizogenesis.     

Purification of cynarases from artichoke (Cynara scolymus L.): enzymatic properties of cynarase A

Aspartic proteinases from flowers of Cynara cardunculus have been extensively studied and long used as coagulants in the manufacture of several traditional Spanish and Portuguese cheeses. These endopeptidases are called cardosins or cynarases, depending on the authors. However, the proteinases of another plant of the genus Cynara, the artichoke (Cynara scolymus), are less known, probably because the flower of this plant is usually consumed as a vegetable. In the study described here, three proteinases (cynarases A, B and C) with milk-clotting properties were purified from the stigma of artichoke. All three proteinases are glycoproteins and composed of a one large and one small subunit. The enzymatic properties of cynarase A, a glycoprotein containing N-linked high mannose type glycans, which express maximum activity at pH 5.0 and 70 degrees C, were studied in detail. Catalytic and inhibition studies indicated that this cynarase is of the aspartic acid type. The results indicate artichoke extract could also be used in the milk industry in the same way as the extract obtained from the flower of C. cardunculus.     

朝鲜蓟的研究进展

朝鲜蓟具有很高的营养、药用和观赏价值,富含维生素、蛋白质、铁、磷、钙等多种营养成分和菜蓟酸、天门冬酰胺等化合物,其生物活性逐渐受到人们的关注.该文对朝鲜蓟的化学成分和生物活性的研究进展进行了综述,为进一步开发利用提供依据.     

Characterisation and pathogenicity of bacteria from shoot tips of the globe artichoke (Cynara scolymus L.)

Bacteria have been isolated from shoot tips of symptomless globe artichoke plants. These were identified as Pseudomonas fluorescens, Pseudomonas marginalis, Pseudomonas spp., Serratia liquefaciens, Enterobacter agglomerans/Erwinia, Agrobacterium radiobacter, an unidentified member of Rhizobiaceae and another classified in the “corynebacteria” group. The most frequently isolated species was P. fluorescens, biovars II and III. The endogenous character of these bacteria was studied in plants growing in vitro and in the open field. P. fluorescens, P. marginalis, S. liquefaciens and E. agglomerans/Erwinia caused symptoms in plants growing in vitro, but only P. fluorescens biovar II and P. marginalis produced symptoms in plants growing in open fields. Differences in pathogenicity were observed on inoculated plants growing in vitro or in the open field. This suggests that several endophytic bacterial species may be responsible for the high levels of contaminants found during the micropropagation of globe artichoke.     

朝鲜蓟叶中的酚性糖苷化合物

从朝鲜蓟（Cynara scolymus）叶中分离得到2个酚性糖苷化合物,其中一个是新化合物,通过波谱学方法确定其结构为2-甲氧基-4-（2,3-二羟基-丙酰基）-苯基-1—O-（6′-O-没食子酰基）-β-D-吡喃葡萄糖苷（1）。     

Mass propagation of globe artichoke (Cynara scolymus): Evaluation of different hypotheses to overcome vitrification with special reference to water potential

In search of a technique for rapid clonal propagation and sanitation of Cynara scolymus L. we have been confronted with the problem of vitrification.
We only succeeded in overcoming this problem by raising the agar concentration of our medium to 1.1% instead of 0.6%. By using the Chardakov-method and direct measurement of the water potential with a thermocouple psychrometer we were able to prove that this result was attributable to the matric potential.     

朝鲜蓟叶中一个新的倍半萜内酯

从朝鲜蓟（Cynarascolyrnus）叶中分离得到2个倍半萜内酯,其中一个是新化合物,通过波谱学方法确定其结构为3β,8α,11α,13-四羟基-10（14）-愈创木烯-1α,4β,5α,6β氢-6α,12-内酯（1）。     

A first linkage map of globe artichoke (Cynara cardunculus var. scolymus L.) based on AFLP, S-SAP, M-AFLP and microsatellite markers

We present the first genetic maps of globe artichoke (Cynara cardunculus var. scolymus L. 2n=2x=34), constructed with a two-way pseudo-testcross strategy. A F₁ mapping population of 94 individuals was generated between a late-maturing, non-spiny type and an early-maturing spiny type. The 30 AFLP, 13 M-AFLP and 9 S-SAP primer combinations chosen identified, respectively, 352, 38 and 41 polymorphic markers. Of 32 microsatellite primer pairs tested, 12 identified heterozygous loci in one or other parent, and 7 were fully informative as they segregated in both parents. The female parent map comprised 204 loci, spread over 18 linkage groups and spanned 1330.5 cM with a mean marker density of 6.5 cM. The equivalent figures for the male parent map were 180 loci, 17 linkage groups, 1239.4 and 6.9 cM. About 3% of the AFLP and AFLP-derived markers displayed segregation distortion with a P value below 0.01, and were not used for map construction. All the SSR loci were included in the linkage analysis, although one locus did show some segregation distortion. The presence of 78 markers in common to both maps allowed the alignment of 16 linkage groups. The maps generated provide a firm basis for the mapping of agriculturally relevant traits, which will then open the way for the application of a marker-assisted selection breeding strategy in this species.     

Anti-hyperlipidemic sesquiterpenes and new sesquiterpene glycosides from the leaves of artichoke (Cynara scolymus L.): structure requirement and mode of action

The methanolic extract from the leaves of artichoke (Cynara scolymus L.) was found to suppress serum triglyceride elevation in olive oil-loaded mice. Through bioassay-guided separation, sesquiterpenes (cynaropicrin, aguerin B, and grosheimin) were isolated as the active components together with new sesquiterpene glycosides (cynarascolosides A, B, and C). The oxygen functional groups at the 3- and 8-positions and exo-methylene moiety in alpha-methylene-gamma-butyrolactone ring were found to be essential for the anti-hyperlipidemic activity of guaiane-type sesquiterpene. In addition, inhibition of gastric emptying was shown to be partly involved in anti-hyperlipidemic activity.     

Kinetic study of the effects of calcium ions on cationic artichoke (Cynara scolymus L.) peroxidase: calcium binding, steady-state kinetics and reactions with hydrogen peroxide

The apparent catalytic constant (k(cat)) of artichoke (Cynara scolymus L.) peroxidase (AKPC) with 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid) (ABTS) increased 130-fold in the presence of calcium ions (Ca2+) but the affinity (K(m)) of the enzyme for ABTS was 500 times lower than for Ca2+-free AKPC. AKPC is known to exhibit an equilibrium between 6-aquo hexa-coordinate and penta-coordinate forms of the haem iron that is modulated by Ca2+ and affects compound I formation. Measurements of the Ca2+ dissociation constant (K(D)) were complicated by the water-association/dissociation equilibrium yielding a global value more than 1000 times too high. The value for the Ca2+ binding step alone has now been determined to be K(D) approximately 10 nM. AKPC-Ca2+ was more resistant to inactivation by hydrogen peroxide (H(2)O(2)) and exhibited increased catalase activity. An analysis of the complex H(2)O(2) concentration dependent kinetics of Ca2+-free AKPC is presented.