Seasonal plasticity is more important than population variability in effects on white clover architecture and productivity

Background and AimsThe drivers of white clover (Trifolium repens) architecture and productivity are still imperfectly understood. Our aim here was to investigate the impact of genetic background, neighbourhood and season on different architectural traits, clover and total biomass yield, as well as the relationship between those traits and yield.MethodsWe grew eight white clover populations in pure stands and in mixed stands with contrasting mixture partners. Over four consecutive regrowth periods within 1 year, we measured trait sizes and determined clover and total yield amounts.Key ResultsThe size of the architectural traits differed between populations and changed in response to neighbourhood and season. Population did not affect the sign or degree of those changes. Among the tested factors, season was by far the most important driver of white clover architecture, with the seasonal pattern notably differing between architectural traits. Clover and total yield were positively related to the architectural traits leaf area, petiole length, internode length and specific leaf area. Whereas the direction of the relationship was widely unaffected, its magnitude was clearly altered by neighbourhood and season.ConclusionsOur results show that seasonal effects are the key for a deeper understanding of the architecture of white clover individuals and to improve the productivity of white clover communities.     

Phosphate availability in combination with nitrate availability affects root yield and chicon yield and quality of Belgian endive (Cichorium intybus)

This study investigated the effects of nitrate and phosphate nutrition on chicory tap root development and chicon quality. Plants of chicory (Cichorium intybus flash) were grown on four concentrations of nitrate and phosphate: 3 mM NO₃ / 1 mM PO ₄ ^3– , high N and high P (control plants, N / P); 3 mM NO ₃ ^– / 0.05 mM H₂PO^3– ₄, high N and low P (N / p); 0.6 mM NO₃ / 1 mM PO ₄ ^3– , low N and high P (n / P); 0.6 mM NO ₃ ^– / 0.05 mM PO ₄ ^3– , low N and low P (n / p). The results suggested that, nitrogen limitation had the greatest impact on the shoot/root dry weight ratio. Only small changes in the shoot/root dry weight could be attributed to P limitation alone. Compared with the control, N limitation caused a marked increase in root SST activity (sucrose sucrose fructosyl transferase, the enzyme responsible for fructan synthesis in roots), the effect of P limitation on SST activity was less pronounced. The activity of SS (sucrose synthase) was also noticeably elevated at the early sample data by N limitation. N and P uptake were estimated by the amount of N and P accumulated by the whole plant during the vegetative period. With N limitation, P accumulation was decreased by 40-60% over the experimental period. The effects of P limitation on N accumulation were more variable, N uptake was 60% lower than the control during the tuberizing period (107 days after sowing). With N limitation, P concentrations in roots were lowered by 20-25%. With P limitation, total N concentration in roots decreased by 50% relative to the control, while nitrate concentration was increased more than 8 fold. These effects were detected only at 107 DAS. The amino acid content of roots was not affected by P limitation, however, N limitation altered strongly total amino acids. P limitation did alter the relative amino acid composition of roots early in the vegetative period: Roots harvested at the end of vegetative period were forced in the dark to produce an etiolated bud, the edible chicon. High N and high P fertility (N/P) were associated to a poor chicon yield and quality. However the presence of low P during vegetative growth moderates adverse effects of high nitrate and greatly improved chicon yeild and quality.     

In vivo and in vitro flowering response of chicory (Cichorium intybus L.): influence of plant age and vernalization

Chicory plants (Cichorium intybus L. var foliosum cv Flash) were tested with and without a 4-week-long cold treatment for in vivo and in vitro flowering potential every 2 weeks during the growing season. One hundred percent of the plants harvested 112 days or later after sowing and then vernalized flowered in vivo. In vitro, no vernalization was needed to initiate flowering-stems on chicory explants taken from roots of 100 days old and older. 5-Azacytidine, a DNA demethylation agent, increased the flowering percentage on explants from young, vernalized roots but could not induce more than 15% flowering on young, nonvernalized roots. The greater flowering potential of chicory root explants in vitro when compared to plants of the same age tested in vivo was clearly established. This result suggests that some negative control on flowering was removed when root explants were excised and the main plant body discarded. Received: 31 August 1998 / Revision received: 27 October 1998 / Accepted: 10 November 1998     

An in vitro model for the study of hydroponic forcing in chicory (Cichorium intybus)

An in vitro model for studying the influence of different factors on chicon formation during hydroponic forcing has been developed. The shoot apex was isolated from the chicory roots and cultured on a gelled nutrient medium. This medium was considered as a replacement of the root. Small chicons (5 g) were produced. Water and, more importantly, sucrose availability had important influences on the outgrowth of the chicons. When sucrose was added to the medium the chicon-weight increased two-fold. On a medium with low agar concentration (0.3% (w/v)), heavier chicons were produced compared with a medium with agar at 1.2% (w/v). Browning of the pith tissue (= flowering stem) decreased with increased agar concentration. The results presented indicate that the in vitro system can be used as a research model to study chicon development in relation to root functioning and composition. This revised version was published online in June 2006 with corrections to the Cover Date.     

Chemosystematic investigations on phenolics from flowerheads of Central European taxa of Hieracium sensu lato (Asteraceae)

 HPLC-UV and HPLC-MS investigations of phenolic acids and flavonoids in flowerheads of 84 samples of 76 taxa belonging to 66 species of Hieracium resulted in the identification of three phenolic acids (chlorogenic acid, 3,5-dicaffeoyl quinic acid, 4,5-dicaffeoyl quinic acid) and six flavonoids (apigenin 4^′-O-β-D-glucuronide, isoetin 4^′-O-β-D-glucuronide, luteolin, luteolin 7-O-β-D-glucoside, luteolin 7-O-β-D-glucuronide, luteolin 4^′-O-β-D-glucoside). The contents of these secondary metabolites were quantified by HPLC using quercetin and cynarin as internal standards. In contrast to the previously investigated genera Leontodon and Crepis, cichoric acid and caffeoyl tartaric acid were not found in any of the investigated Hieracium taxa. Results of HPLC analyses revealed only a limited degree of qualitative variation between the different taxa, and luteolin 7-O-β-D-glucuronide and isoetin 4^′-O-β-D-glucuronide were the only compounds, which were not detectable in some of the investigated taxa. Quantitative patterns of phenolics differed markedly between particular taxa and Principal Component Analysis of the quantification results yielded separate clusters for the members of the subgenera Hieracium and Pilosella. Received January 23, 2001 Accepted October 11, 2001     

The temporal development in a hybridizing population of wild and cultivated chicory (Cichorium intybus L.)

Hybridization and its possible impacts is a subject of increased attention in connection with the risk of unintended gene flow from cultivated (including genetically modified) plants to wild relatives. Whether such gene flow by hybridization is likely to take place depends among other things on the persistence of the hybrids in a natural environment over time. To evaluate this, we studied an experimental hybridizing population of wild and cultivated chicories (Cichorium intybus) relative to a previous study on the same population 2 years earlier. We compared the genetic composition, morphology and fitness traits of plants from 2004 to the plants in the same plot in 2002. The majority of the plants in 2004 was more morphologically and genetically intermediate than in 2002. This indicates that no selection towards being wild-like or cultivar-like was present over the period of 2 years. Furthermore, no distinct fitness differences existed between the plants of 2004, probably due to most of the plants being intermediate. No hybridization barriers appeared to be present between wild and cultivated chicories beyond the F1 generation, since F2 hybrids and backcrosses were in abundance; in fact, hybrids of probably fourth or fifth generation were present. In conclusion, all results indicate that no barriers exist to the temporal persistence of chicory hybrids in a natural environment.     

Purification and characterization of 1-SST, the key enzyme initiating fructan biosynthesis in young chicory roots (Cichorium intybus)

A genuine 1-SST (sucrose:sucrose 1-fructosy] transferase, EC 2.4.1.99) was purified and characterized from young chicory roots ( Cichorium intybus L. var. foliosum cv. Flash) by a combination of ammonium sulfate precipitation, concanavalin A affinity chromatography, anion and cation exchange chromatography. This protocol produced a 63-fold purification and a specific activity of 4.75 U (mg protein)⁻¹. The mass of the enzyme was 69 kDa as estimated by gel filtration. On SDS-PAGE apparent molecular masses of 49 kDa (α-subunit) and 24 kDa (β-subunit) were found. Further specification was obtained by MALDI-TOF MS detecting molecular ions at m/z 40109 and 19 896. These two fragments were also found on a western blot using an SDS-boiled chicory root extract and chicken-raised polyclonal antibodies against the purified 1-SST, indicating that the enzyme is a heterodimer in vivo. The N-terminus of chicory root 1-SST α-subunit was shown to be highly homologous with the cDNA-derived amino acid sequences from barley 6-SFT and a number of β-fructosyl hydrolases (in-vertases and fructan hydrolases). However, chicory root 1-SST properties could be clearly differentiated from those of chicory root 1-FFT (EC 2.4.1.100), chicory root acid invertase (EC 3.2.1.26) and yeast invertase. The enzyme mainly produced 1-kes-tose and glucose from physiologically relevant sucrose concentrations, indicating that this 1-SST is the key enzyme initiating fructan biosynthesis in vivo. However, like chicory root 1-FFT and barley 6-SFT, the enzyme also showed some β-fructofuranosi-dase activity (fructosyl transfer to water) at very low sucrose concentrations. Although sucrose clearly is the best substrate for the enzyme, some transferase and β-fructofuranosidase activity were also detected using 1-kestose as the sole substrate.     

Purification and characterization of 1-SST, the key enzyme initiating fructan biosynthesis in young chicory roots (Cichorium intybus)

A genuine 1-SST (sucrose:sucrose 1-fructosy] transferase, EC 2.4.1.99) was purified and characterized from young chicory roots ( Cichorium intybus L. var. foliosum cv. Flash) by a combination of ammonium sulfate precipitation, concanavalin A affinity chromatography, anion and cation exchange chromatography. This protocol produced a 63-fold purification and a specific activity of 4.75 U (mg protein)⁻¹. The mass of the enzyme was 69 kDa as estimated by gel filtration. On SDS-PAGE apparent molecular masses of 49 kDa (α-subunit) and 24 kDa (β-subunit) were found. Further specification was obtained by MALDI-TOF MS detecting molecular ions at m/z 40109 and 19 896. These two fragments were also found on a western blot using an SDS-boiled chicory root extract and chicken-raised polyclonal antibodies against the purified 1-SST, indicating that the enzyme is a heterodimer in vivo. The N-terminus of chicory root 1-SST α-subunit was shown to be highly homologous with the cDNA-derived amino acid sequences from barley 6-SFT and a number of β-fructosyl hydrolases (in-vertases and fructan hydrolases). However, chicory root 1-SST properties could be clearly differentiated from those of chicory root 1-FFT (EC 2.4.1.100), chicory root acid invertase (EC 3.2.1.26) and yeast invertase. The enzyme mainly produced 1-kes-tose and glucose from physiologically relevant sucrose concentrations, indicating that this 1-SST is the key enzyme initiating fructan biosynthesis in vivo. However, like chicory root 1-FFT and barley 6-SFT, the enzyme also showed some β-fructofuranosi-dase activity (fructosyl transfer to water) at very low sucrose concentrations. Although sucrose clearly is the best substrate for the enzyme, some transferase and β-fructofuranosidase activity were also detected using 1-kestose as the sole substrate.     

Total phenolic,size‐fractionated phenolics and fucoxanthin content of tropical Sargassaceae (Fucales,Phaeophyceae) from the South Pacific Ocean: Spatial and specific variability

This innovative study investigates 18 Turbinaria and Sargassum brown seaweed samples from three archipelagos of the South West Pacific Ocean. The phenolic content of crude and size‐fractionated extracts was determined by the Folin‐Ciocalteu method; fucoxanthin was measured using high performance liquid chromatography. Although the phenolic content proved to be low for the species of both genera tested, the levels in the species of Turbinaria were higher than those of Sargassum tested, except in the Fiji islands where both species produced similar contents. These investigations also highlighted variations of total phenolic content with spatial, reef morphology and depth. A large number of small phenolic compounds (<2000 Da) were observed irrespective of the genus analyzed. Nevertheless, the composition of the phenolic pool varied in relation with the genus, the archipelago from which the material was collected, geomorphological features and the depth of each collection field site. A similar observation was for fucoxanthin content and in general, the measured constituents of the Turbinaria were less than those of the Sargassum species. The results are discussed in terms of inter‐ and intra‐specific variability. Variations in both phenolic and fucoxanthin content were noted in tropical members of the Sargassaceae; such differences could be a result of specific chemical defense mechanisms adopted by members of each genus.     

Effect of Seasonal and Regional Variations on Phenolic Compounds of Deverra scoparia (Flowers/Seeds) Methanolic Extract and the Evaluation of Its in Vitro Antioxidant Activity

The widespread use of Deverra scoparia Coss. & Durieu in Algerian folk‐medicine as a remedy can be relatively attributed to its total phenolic compounds. The current study aimed to provide a scientific basis for optimal collection and usage of Deverra scoparia Coss. & Durieu plant. Hence, 37 samples were gathered from nine sites in Algeria during two seasons 2016 and 2017, then exposed to a green extraction. Total phenolic (TPC), flavonoid (FC) and condensed tannins (CTC) content were estimated spectrophotometrically. The antioxidant activity was measured using five different methods, DPPH^., ABTS^.+, FRAP, CUPRAC and Fe²⁺‐chelating. The results have revealed considerable amounts of TPC varied from 804 to 1544 mg GAE/100 g dry matter, FC started from 187 up to 410 mg QE/100 g dry matter and CTC varied from 111 to 394 mg CE/100 g dry matter. The best IC₅₀ values (μg/mL) of DPPH^., ABTS^?+, FRAP, CUPRAC and Fe²⁺‐chelating tests were 56.62, 5.41, 21.26, 52.93 and 78.10, respectively. Moreover, high correlations were found between CTC and most of the antioxidant tests. Hence, CTC are suggested to be the principal group of antioxidant activity in Deverra scoparia Coss. & Durieu extracts.     

Seasonal dynamics of carbohydrate and nitrogenous components in the roots of perennial weeds

Abstract Chicory (Cichorium intybus L.) and dandelion (Taraxacum officinale L.) are persistent weeds, the aerial portions of which do not survive in winter. However, subterranean tissues remain viable and facilitate the rapid resumption of growth in early spring. The source of nutrients for growth prior to the establishment of foliage is the roots. Carbohydrate and N reserves are accrued during late summer and autumn, respectively. Hydrolysis of fructans during late autumn occurs coincidentally with increments in sucrose, the latter providing a readily accessible C pool. Nitrate, free amino acids and soluble protein all play substantial roles in nitrogen storage. Asparagine is the predominant amino acid in the free pool during winter, followed by glutamine, ornithine, serine, aspartic acid and glutamic acid. Storage reserves remain at peak levels throughout winter and deeline prior to the resumption of growth. The patterns observed here provide evidence that N is an important currency of storage metabolism and, thus, a framework has been provided for the examination of regulation of N storage in perennial weeds.     

Histolocalization of chemotaxonomic markers in Brazilian Vernonieae (Asteraceae)

Vernonieae are well represented in South America by subtribe Lychnophorinae, with 104 Brazilian species, some of them rare and endangered. Lychnophorinae are well known for producing metabolites of high pharmaceutical and chemotaxonomic value. Despite the importance of secondary metabolites in Lychnophorinae, there is still little evidence regarding the secretory structures responsible for producing these compounds. Therefore, in this study we investigated 15 species representative of the main lineages of Lychnophorinae, with the following objectives: to identify where the chemotaxonomic markers of Lychnophorinae are secreted and stored and in which developmental stage of the organ these metabolites are found. Samples of stems and leaves were processed according to the usual techniques in plant anatomy. It was found that the main sites of secondary metabolite biosynthesis are glandular trichomes, epidermal cells and parenchyma tissues. Metabolites from glandular trichomes, especially sesquiterpene lactones (STL), are prevalent in the early developmental stages of organs. The metabolite compounds stored in parenchyma tissues are mainly terpenoids, flavonoids and other phenolic compounds; young and expanded leaves are equally rich in metabolites. Thus, the information obtained in this study is essential for conducting chemotaxonomic studies in this group, helping to promote selective collection and conservation of species.     

Genetic analysis and conservation of the endangered Canary Island woody sow-thistle, Sonchus gandogeri (Asteraceae)

Sonchus gandogeri, a woody sow-thistle, is an endangered Canary Island endemic with only two known populations, one in the El Golfo and another in the Las Esperillas of El Hierro. Amplified fragment length polymorphism (AFLP) markers were used to assess the genetic variation within and among populations. The mean genetic diversity of two populations was estimated to be 0.380, and the El Golfo population (0.380) had higher genetic diversity than the southeastern one (0.268). The unbiased Neis genetic identity between the two populations was 0.846. The mean genetic diversity of S. gandogeri was much higher than that of the other endangered plant species. This is perhaps due to breeding system, life form, extinction, and/or introgressive hybridization and hybrid origin of the taxon. This study also indicates that the two populations are not strongly differentiated (G_ST=0.149). This study suggests that S. gandogeri is more likely to become extinct due to environmental or demographic forces than genetic factors, such as inbreeding depression. More strict control of introduced herbivores is necessary to protect these populations, and germplasm collection for ex situ conservation is needed.     

忍冬属植物花药药隔的特化结构及其生物学意义

花药药隔的特化结构通常具有重要的生物学意义。目前,有关药隔特化出贮存酚类物质的异细胞群的研究报道甚少,该特化结构有何生物学意义则未见报道。本研究运用半薄切片技术、冰冻切片技术、组织化学和细胞化学等方法对忍冬属Lonicera植物特化药隔异细胞群的主要内含物进行定性分析,实验证明忍冬属特化药隔异细胞群内含丰富的酚类物质。另外通过对忍冬属华南忍冬L.confusa药隔薄壁组织的发育及其与药隔维管束的关系分析,推测忍冬属特化药隔可能一方面对发育中的花药维管束起保护作用,另一方面又可作为酚类物质的临时贮存场所。同时研究发现忍冬属植物特化药隔异细胞群的形成及其分布特点可能具有重要的系统学意义。     

Cleistogamy inCentaurea melitensis (Asteraceae): Capitulum variability and spatio-temporal development patterns

Centaurea melitensis is a cleistogamous species of Mediterranean distribution, which normally produces a wide range of capitula varying in terms of morphology, size, position in the shoot system and other aspects. For that reason, and particularly in view of the pseudanthic nature of the flower head in Asteraceae, a preliminary study to characterise cleistogamy in this species was considered of interest. Capitular heteromorphism observed inC. melitensis was confirmed by principal component analysis (PCA). The five capitulum types differentiated [initial cleistogamous (iCL), intermediate cleistogamous (xCL), final cleistogamous (fCL), pseudocleistogamous (PCL) and chasmogamous (CH)] fit development patterns specific for both placement on the plant and timing. The balance between cleistogamy and chasmogamy is correlated with the final height of the plant. All these features are consistent with those reported for other cleistogamous species.     

Phylogenetic relationships among Lactuca (Asteraceae) species and related genera based on ITS-1 DNA sequences

Internal transcribed spacer (ITS-1) sequences from 97 accessions representing 23 species of Lactuca and related genera were determined and used to evaluate species relationships of Lactuca sensu lato (s.l.). The ITS-1 phylogenies, calculated using PAUP and PHYLIP, correspond better to the classification of Feráková than to other classifications evaluated, although the inclusion of sect. Lactuca subsect. Cyanicae is not supported. Therefore, exclusion of subsect. Cyanicae from Lactuca sensu Feráková is proposed. The amended genus contains the entire gene pool (sensu Harlan and De Wet) of cultivated lettuce (Lactuca sativa). The position of the species in the amended classification corresponds to their position in the lettuce gene pool. In the ITS-1 phylogenies, a clade with L. sativa, L. serriola, L. dregeana, L. altaica, and L. aculeata represents the primary gene pool. L. virosa and L. saligna, branching off closest to this clade, encompass the secondary gene pool. L. virosa is possibly of hybrid origin. The primary and secondary gene pool species are classified in sect. Lactuca subsect. Lactuca. The species L. quercina, L. viminea, L. sibirica, and L. tatarica, branching off next, represent the tertiary gene pool. They are classified in Lactuca sect. Lactucopsis, sect. Phaenixopus, and sect. Mulgedium, respectively. L. perennis and L. tenerrima, classified in sect. Lactuca subsect. Cyanicae, form clades with species from related genera and are not part of the lettuce gene pool.