Variation and correlation analysis of flavonoids and carotenoids in Korean pigmented rice (Oryza sativa L.) cultivars

Flavonoids and carotenoids of pigmented rice ( Oryza sativa L.), including five black cultivars and two red cultivars, from Korea were characterized to determine the diversity among the phytochemicals and to analyze the relationships among their contents. Black cultivars were higher in flavonoids and carotenoids than the red and white cultivars. The profiles of eight phytochemicals identified from the rice grains were subjected to principal component analysis (PCA) to evaluate the differences among cultivars. PCA could fully distinguish between these cultivars. The Heugjinjubyeo (BR-1) and Heugseolbyeo (BR-2) cultivars were separated from the others based on flavonoid and carotenoid concentrations. Flavonoid contents had a positive correlation with carotenoid contents among all rice grains. The BR-1 and BR-2 cultivars appear to be good candidates for future breeding programs because they have simultaneously high flavonoid and carotenoid contents.     

Antioxidant capacity and phenolic content of spinach as affected by genetics and growing season

Total phenolic content and antioxidant capacity of 11 commercial cultivars and 15 advanced breeding lines of spinach were determined over two growing seasons known to vary in biotic and abiotic stresses. Flavonoid composition and content of fall-grown commercial cultivars and advanced breeding lines were also determined. Over-winter spinach, which was planted in late fall and harvested in the spring, had much higher levels of total phenolics and antioxidant capacity than spinach planted in early fall and harvested in late fall, indicating that growing conditions, as well as biotic and abiotic stresses, influenced phenolic metabolism. Genotype also appeared to play an important role in affecting phenolic metabolism and antioxidant capacity in spinach. Advanced breeding lines of spinach, which show increased disease resistance, had higher levels of total phenolics, individual and total flavonoids, and antioxidant capacity than commercial cultivars. Our results indicate that plant breeders can select for increased phenolic content to increase antioxidant capacity in spinach cultivars, or the crops can be grown in different seasons or under certain stress conditions to elevate levels of antioxidants.     

Role of endogenous flavonoids in resistance mechanism of Vigna to aphids

Cultivated and wild species of the genus Vigna were screened for their flavonoid content. Flavonoid HPLC analyses clearly showed that cultivated lines of cowpea (Vigna unguiculata L. Walp.) are very similar from a qualitative point of view, always showing three flavonoid aglycons: quercetin, kaempferol, and isorhamnetin. In addition, a positive relationship between resistance/susceptibility characteristics against aphids and flavonoid glycoside content of cowpea lines was found. The resistant lines showed a flavonoid content higher than that of susceptible ones. In vitro bioassays proved that, among endogenous flavonoids, quercetin and isorhamnetin possess a good inhibitory aphid reproduction rate. Flavonoid HPLC analyses of wild Vigna species supported evidence for the existence of different flavonoid chemotypes in some species of section Vigna. There are kaempferol chemotypes, kaempferol being the main aglycon detected, quercetin chemotypes, containing quercetin glycosides only, and two isorhamnetin chemotypes. When the resistance characteristics to aphids in different chemotypes of the same species were tested, it became evident that quercetin or isorhamnetin chemotypes showed a higher level of resistance compared to kaempferol chemotypes in the same species, thus demonstrating a direct involvement of quercetin or isorhamnetin in the resistance mechanism. These results can provide useful information for further studies on gene expression of resistance factors.     

The flavonoids of tomatoes

Tomatoes ( Lycopersicon esculentum Mill.) have been recognized as an important source of dietary flavonoids because of a high consumption worldwide. The qualitative and quantitative flavonoid compositions of assorted tomato cultivars including individual quantitative contributions of the five most significant flavonoids have been determined in this work. The dihydrochalcone phloretin 3',5'-di-C-beta-glucopyranoside and the flavonol quercetin 3-O-(2'-O-beta-apiofuranosyl-6'-O-alpha-rhamnopyranosyl-beta-glucopyranoside) were identified for the first time in Solanaceae spp. and found to be among the main flavonoids in all cultivars. Phloretin 3',5'-di-C-glc is the first C-glycoside identified in tomatoes and also the first dihydrochalcone from this species. In addition, chalconaringenin, kaempferol 3-rutinoside, and quercetin 3-rutinoside (rutin), though previously reported to occur in tomato, were fully characterized by extensive use of 2D NMR techniques and high-resolution LCMS. The total flavonoid content of different tomato types varied from 4 to 26 mg 100 (-1) g FW with chalconaringenin as the predominant compound comprising 35 to 71% of the total flavonoid content. The individual quantities of quercetin 3-O-(2'- O-beta-apiofuranosyl-6'- O-alpha-rhamnopyranosyl-beta-glucopyranoside) and phloretin 3',5'-di-C-beta-glucopyranoside was similar to that of rutin in several cultivars.     

Microsatellite-based analysis of genetic diversity in 91 commercial Brassica oleracea L. cultivars belonging to six varietal groups

Brassica oleracea L. includes various types of important vegetables that show extremely diverse phenotypes. To elucidate the genetic diversity and relationships among commercial cultivars derived by different companies throughout the world, we characterized the diversity and genetic structure of 91 commercial B. oleracea cultivars belonging to six varietal groups, including cabbage, broccoli, cauliflower, kohlrabi, kale and kai-lan. We used 69 polymorphic microsatellite markers showing a total of 359 alleles with an average number of 5.20 alleles per locus. Polymorphism information content (PIC) values ranged from 0.06 to 0.73, with an average of 0.40. Among the six varietal groups, kohlrabi cultivars exhibited the highest heterozygosity level, whereas kale cultivars showed the lowest. Based on genetic similarity values, an UPGMA clustering dendrogram and a two-dimensional scale diagram (PCoA) were generated to analyze genetic diversity. The cultivars were clearly separated into six different clusters with a tendency to cluster into varietal groups. Model-based structure analysis revealed six genetic groups, in which cabbage cultivars were divided into two subgroups that were differentiated by their head shape, whereas cauliflower and kai-lan cultivars clustered together into a single group. Furthermore, we identified 18 SSR markers showing 27 unique alleles specific to only one cultivar that can be used to discriminate 22 cultivars from the others. Our phylogenetic and population structure analysis presents new insights into the genetic structure and relationships among 91 B. oleracea cultivars and provides valuable information for breeding of B. oleracea species. In addition, we demonstrate the utility of SSR markers as a powerful tool for discriminating between the cultivars. The SSR markers described herein will also be helpful for Distinctness, Uniformity and Stability (DUS) test of new cultivars.     

Changes in phytochemical and antioxidant activity of selected pepper cultivars (Capsicum species) as influenced by maturity

The effect of fruit maturation on changes in carotenoids, flavonoids, total soluble reducing equivalents, phenolic acids, ascorbic acid, and antioxidant activity (AOX) in different pepper types (Capsicum annuum, Capsicum frutescens, and Capsicum chinese) was determined. Generally, the concentration of these chemical constituents increased as the peppers reached maturity. Peppers contained high levels of L-ascorbic acid and carotenoids at maturity, contributing 124-338% of the RDA for vitamin C and 0.33-336 RE/100 g of provitamin A activity, respectively. Levels of phenolic acids, capxanthin, and zeaxanthin generally increased during maturation, whereas the level of lutein declined. Flavonoid concentrations varied greatly among the pepper types analyzed and were negatively correlated to AOX under the conditions of the beta-carotene-linoleic assay. Model systems were used to aid in understanding the relationship between flavonoids and AOX. Significant increases in AOX were observed in pepper juice models in response to increasing dilution factors and the presence of EDTA, indicating a pro-oxidant effect due to metal ions in the system. In vitro models demonstrated that increasing levels of flavonoids in combination with constant levels of caffeic and ascorbic acid gave a resultant AOX that was either additive of the two compounds or competitive in their ability to scavenge peroxyl radicals. The model systems were in good agreement with the chemical composition of the pepper cultivars and reflected the interactions affecting AOX. More research is needed to understand the complex interactions that occur among various antioxidants present in pepper extracts.     

Age-related variations in flavonoid intake and sources in the Australian population

OBJECTIVE: To estimate flavonoid intake in the Australian population. DESIGN: Flavonoid consumption was estimated from 24-hour recall data and apparent consumption data using US Department of Agriculture flavonoid composition data. SUBJECTS: The National Nutrition Survey 1995 assessed dietary intake (24-hour recall) in a representative sample (n=13,858) of the Australian population aged 2 years and over. RESULTS: Analysis of the 24-hour recall data indicated an average adult intake (>18 years) of 454 mg day(-1) (92% being flavan-3-ols). Apple was the highest quercetin source until age 16-18 years, after which onion became an increasingly important prominent source. Variations in hesperetin consumption reflected orange intake. Apple, apricot and grapes were the major sources of epicatechin and catechin for children, but subsided as wine consumption increased in adulthood. Wine was the main source of malvidin. Naringenin intake remained static as a percentage of total flavonoid intake until age 19-24 years, corresponding to orange intake, and then increased with age from 19-24 years, corresponding to grapefruit intake. Apparent dietary flavonoid consumption was 351 mg person(-1) day(-1), of which 75% were flavan-3-ols. Black tea was the major flavonoid source (predominantly flavan-3-ols) representing 70% of total intake. Hesperetin and naringenin were the next most highly consumed flavonoids, reflecting orange intake. Both 24-hour recall and apparent consumption data indicated that apigenin intake was markedly higher in Australia than reported in either the USA or Denmark, presumably due to differences in consumption data for leaf and stalk vegetables and parsley. CONCLUSIONS: Tea was the major dietary flavonoid source in Australia. Flavonoid consumption profiles and flavonoid sources varied according to age. More consistent methodologies, survey tools validated for specific flavonoid intakes and enhanced local flavonoid content data for foods would facilitate better international comparisons of flavonoid intake.     

Association of Avenanthramide Concentration in Oat (Avena sativa L.) Grain with Crown Rust Incidence and Genetic Resistance

Avenanthramides (avn) are antioxidant compounds found in oat tissues, including the grain, that are of interest from a nutritional standpoint. In this study, we have measured avenanthramide concentration in the grain of 18 oat genotypes grown in six environments. These genotypes varied widely in crown rust (Puccinia coronata) resistance. Crown rust infected two of the six environments studied. The grain avenanthramide concentrations in the crown rust environments were significantly higher than those in the uninfected environments. Avenanthramide concentrations in the crown rust infected environments was also significantly correlated with their genetic crown rust resistance, as evaluated in the field. These results suggest that avenanthramide accumulation in the grain is associated with crown rust infection and that, in most of the cultivars evaluated, the extent of their accumulation also correlated with their genetic disease resistance; avenanthramide accumulation in the grain was, with noted exceptions, highest in those cultivars showing the greatest genetic resistant to crown rust.     

Chromatographic fingerprint analysis and rutin and quercetin compositions in the leaf and whole-plant samples of di- and tetraploid Gynostemma pentaphyllum

Gynostemma pentaphyllum (Thunb.) Makino, also known as jiaogulan, has been shown to have antioxidant, antiproliferative, and anti-inflammatory activities. Flavonoid is considered a major contributor for these beneficial effects. To obtain chemical patterns of flavonoids in G. pentaphyllum of different genotypes (di- versus tetraploids) and different parts (leaf versus whole plant) of plants, the extraction condition was optimized and a fingerprinting approach was established by means of high-performance liquid chromatography coupled with diode array detection and mass spectrometry (HPLC-DAD-MS). Eight flavonoids were identified, among which rutin and quercetin were quantified. The highest levels of rutin and quercetin were 23.03 and 12.10 mg/g, respectively, observed in the diploid leaf sample 2L3 and 2L2, while the lowest levels of rutin and quercetin were 1.92 and 0.25 mg/g in the tetraploid whole-plant sample 4W3. The chemical patterns were further analyzed by similarity calculation and principal component analysis (PCA). Seven common characteristic peaks were found in all of the tested samples. Flavonoid patterns of tetraploids were significantly different from those of diploids, whereas different parts of plants showed less difference. The flavonoid pattern of the diploid leaf sample was most similar to that of the reference botanical G. pentaphyllum. The combination of chromatographic fingerprint and quantification analysis could be used for quality assessment of G. pentaphyllum and its derived nutraceutical products.     

Differential resistance of switchgrass <Emphasis Type="Italic">Panicum virgatum</Emphasis> L. lines to fall armyworms <Emphasis Type="Italic">Spodoptera frugiperda</Emphasis> (J. E. Smith)

Six cultivars of switchgrass Panicum virgatum L., a plant native to North America that has potential as a bioenergy source, were evaluated for resistance to feeding by the fall armyworm Spodoptera frugiperda (J. E. Smith). Although no mortality was noted, seedlings of the cultivar ‘Trailblazer’ and older plants of the cultivar ‘Blackwell’ were among the most resistant to feeding by S. frugiperda. Some field-collected samples from natural habitat were fed upon by S. frugiperda as readily as were the cultivars, while others caused high mortality after 2 days. Enzyme assays indicated relative differences in expression of two peroxidases thought to be involved in insect resistance in maize, but not in two chitinolytic enzymes. Genomic searches based on maize-sequence templates for the aforementioned genes identified homologs in switchgrass. Sequencing of cDNA coding for these genes identified some differences, especially in the cationic peroxidase, which could influence relative activity. These results indicate switchgrass germplasm has varying resistance to fall armyworms which could be a function of gene sequence diversity, as well as of variation in gene expression due to differences in ploidy levels or other factors.     

Phenolic, flavonoid, and lutein ester content and antioxidant activity of 11 cultivars of chinese marigold

This study analyzed 11 Chinese cultivars of marigold to determine their major phytochemical contents and antioxidant activities. Dried marigold flowers were extracted with ethanol, ethyl acetate, and n-hexane and the extracts were analyzed by high-performance liquid chromatography-mass spectrometry and chemical methods to determine their lutein esters, phenolic and flavonoid contents, and antioxidant activity, respectively. The different cultivars of marigold showed considerable variations in their lutein ester contents, ranging from 161.0 to 611.0 mg/100 g of flower (dry basis). The lutein esters in marigolds consisted predominantly of six all trans-diesters, but small amounts of cis isomers of the respective diesters were also present. The different cultivars of marigold also showed marked variations in total phenols and flavonoids, as well as antioxidant and radical-scavenging activities. Ethanol was confirmed to be the best solvent for extracting both phenols and flavonoids from marigold flowers, while n-hexane was the worst. The ethanolic extracts also exhibited the highest antioxidant and radical-scavenging activities. The cultivar Xinhong had the highest phenolic and flavonoid contents and radical-scavenging activity, as well as one of the highest lutein contents and antioxidant activities.     

Exploration of intra- and inter-population genetic diversity in <Emphasis Type="Italic">Hedysarum coronarium</Emphasis> L. by AFLP markers

Amplified fragment length polymorphism (AFLP) markers were used to characterize the genetic diversity within and among natural populations and cultivars of Hedysarum coronarium. Twelve populations within Tunisia were evaluated with three AFLP primer combinations. A total of 207 reproducible bands was detected of which 178 (86%) were polymorphic. The great discriminative power of AFLP markers and their ability to represent genetic relationships among Hedysarum plants was demonstrated. Genetic diversity within and among populations was assessed through Principal Component Analysis (PCA) and cluster analysis by using the Neighbor-joining clustering algorithm. AFLP technology has provided evidence of a high degree of intra- and inter-population genetic diversity in H. coronarium. AFLP banding patterns provided molecular markers correlated with the plants’ geotropism. In addition, AFLP markers can differentiate wild accessions from cultivars. Moreover, geographical origins did not correspond to population clustering.     

Genetic diversity and relationships between wild and cultivated olives (<Emphasis Type="Italic">Olea europaea</Emphasis> L.) in Sardinia as assessed by SSR markers

The genetic relationships within and between wild and cultivated olives were examined and clarified in an isolated and restricted area, such as the Mediterranean island of Sardinia. Wild (21 individuals) and cultivated olive trees (22 local cultivars from a germplasm collection and 35 ancient trees) were genotyped by means of 13 SSR loci. Five cases of synonymy were observed and nine distinct genotypes were identified in the collection. Five novel genotypes were also detected among the ancient trees. Differences on the allelic composition and heterozygosity levels were found between wild and cultivated trees. Model-based clustering method classified the olive trees into two major gene pools: (a) wild genotypes and (b) local cultivars from the collection and from heritage olives. Regarding the cultivated plant material, we observed that: (a) most of the Sardinian cultivars shared the same allelic profiles with the ancient cultivated trees and (b) the majority of these cultivars and all the novel genotypes were not related to any other cultivars included in this study. These findings as well as the detection of unique alleles and a certain wild genetic background at some cultivars revealed by the Bayesian analysis may indicate their autochthonous origin. The synonymy cases found between local cultivars and Italian mainland cultivars indicate interchange of genetic material among these growing areas, suggesting thus a possible allochthonous origin. The information obtained can assist in the management of an olive collection and sheds some light on the survival of true oleasters and the origin of Sardinian cultivars.     

A chemosystematic study of the flavonoids of Vigna

Summary Flavonoid chemical markers together with other biochemical markers and/or morphological data can provide useful characters for defining species in Vigna genus. In this paper flavonid HPLC fingerprints have been utilized to assess taxonomic relationships amongst species and accessions of Vigna. Within the taxa analysed there is evidence of both infra- and interspecific chemical variations. In some species chromatographic data support evidence for the existence of different flavonoid chemotypes, which may reflect differences in geographic origin. As far as interspecific relationships are concerned, species belonging to sections Vigna, Plectotropis and Ceratotropis do not show flavonoid glycosides in common with cultivated lines of Vigna. By contrast, some relationships have been found between cultivated lines and wild species of section Catiang. Kaempferol-3-rutinoside and an unidentified kaempferol-glycoside were the only flavonoids detected in the three subgenera analysed. Finally, a greater variability in flavonoid aglycone class and glycosylation pattern has been observed in cultivars of V. unguiculata (L.) Walp. compared to the wild species. This observation may confirm that cultivation and/or domestication may cause or increase species diversification.     

Insect resistance of a full sib family of tetraploid switchgrass Panicum virgatum L. with varying lignin levels

Little information is available on insect resistance mechanisms and inheritance in biomass grasses. Although reduction of lignin in biomass grasses in order to increase the efficiency of fermentation may result in increased susceptibility to insect feeding, other resistance mechanisms may be more important. Field grown leaves of two tetraploid parent (Kanlow N1, Summer) and 14 progeny switchgrass (Panicum virgatum L.) plant clones selected for a diversity of plant form and ranges in lignin levels were tested for leaf resistance to feeding by the fall armyworm (Spodoptera frugiperda J. E. Smith), a grass feeding insect pest. Although lignin generally appeared important as a resistance mechanism only at early season stages, replicate clones of two low lignin progeny plants generally remained resistant to fall armyworm feeding. Mechanical damaging increased resistance to fall armyworm feeding in several of these plants. Degrees of resistance were sometimes associated with leaf form of progeny. These results indicate there are likely multiple insect resistance mechanisms operating at different stages in switchgrass, and that segregation of some mechanisms appears related to growth form of the plants.     

Quantitative high-performance liquid chromatography analyses of flavonoids in Australian Eucalyptus honeys

Flavonoids of nine Australian monofloral Eucalyptus honeys have been analyzed and related to their botanical origins. The mean content of total flavonoids varied from 1.90 mg/100 g of honey for stringybark (E. globoidia) honey to 8.15 mg/100 g of honey for narrow-leaved ironbark (E. crebra) honey, suggesting that species-specific differences occur quantitatively among these Eucalyptus honeys. All of the honey samples analyzed in this study have a common flavonoid profile comprising tricetin (5,7,3',4',5'-pentahydroxyflavone), quercetin (3,5,7,3',4'-pentahydroxyflavone), and luteolin (5,7,3',4'-tetrahydroxyflavone), which, together with myricetin (3,5,7,3',4',5'-hexahydroxyflavone) and kaempferol (3,5,7,4'-tetrahydroxyflavone), were previously suggested as floral markers for European Eucalyptus honeys. Thus, flavonoid analysis could be used as an objective method for the authentication of the botanical origin of Eucalyptus honeys. Moreover, species-specific differences can also be found in the composition of honey flavonoid profiles. Among these honeys, bloodwood (E. intermedia) honey contains myricetin and tricetin as the main flavonoid compounds, whereas there is no myricetin detected in yapunyah (E. ochrophloia), narrow-leaved ironbark (E. crebra), and black box (E. largiflorens) honeys. Instead, these types of Eucalyptus honeys may contain tricetin, quercetin, and/or luteolin as their main flavonoid compounds. Compared to honeys from other geographical origins, the absence or minor presence of propolis-derived flavonoids such as pinobanksin, pinocembrin, and chrysin in Australian honeys is significant. In conclusion, these results demonstrate that a common flavonoid profile exists for all of the Eucalyptus honeys, regardless of their geographical origins; the individual species-specific floral types of Eucalyptus honey so common in Australia could be possibly differentiated by their flavonoid profile differences, either qualitatively or quantitatively or both.     

大蒜种质遗传多样性的SSR分析

为了探索中国大蒜种质个体的SSR位点的分布情况,为品种鉴定、保存及遗传改良提供分子生物学依据,利用6对SSR引物对40个大蒜(Allium sativumL.)品种进行聚类分析、主成分分析及遗传多样性评价。共检测到21个多态性位点,平均每对引物可扩增出约3.5条多态性片段,多态性百分率为56.76%;SSR引物组合平均有效等位基因数、Nei基因多样度和Shannon信息指数分别为1.5551、0.3414和0.5188。聚类分析显示,6对SSR引物可把40份大蒜种质资源从0.59相似系数水平上3个类群。第一类群包含28份种质,在相似系数为0.73的水平上进一步又被分成了3个亚类;第二亚类仅包含2份种质;第三亚类包含10份种质,在0.68的相似系数水平上分成了2个亚类。主成分分析和UPGMA的结果基本一致。不同地理来源的大蒜种质的Shannon-Weaver多样性指数的变幅为0.0576~0.4179,说明大蒜种质遗传多样性丰富。本研究利用SSR分子标记技术较准确地解析大蒜不同材料间的亲缘关系及遗传多样性,为中国大蒜SSR分子标记提供基础资料。     

Alterations of flavonoid biosynthesis in young grapevine (Vitis vinifera L.) leaves, flowers, and berries induced by the dioxygenase inhibitor prohexadione-Ca

Prohexadione-Ca is a structural mimic of 2-oxoglutarate, and according to this property, it is able to inhibit dioxygenase enzymes, which require 2-oxoglutarate as a cosubstrate. Such enzymes are involved in flavonoid biosynthesis; therefore, prohexadione-Ca treatment leads to alterations in the flavonoid metabolism in grapevine tissues. Because of the fact that phenolic compounds often are responsible for enhanced plant resistance, modification of phenylpropanoid metabolism using elicitation can be considered as a new potential strategy in plant protection. The phenolic compounds were analyzed by high-performance liquid chromatography combined with chemical reaction detection. Tissue treatment induced the accumulation of unusual flavonoids, which were identified as derivatives of pentahydroxyflavanone, eriodictyol, and luteoliflavan. Concentrations of constitutive flavonoids were also affected by the bioregulator treatment. The alterations of the flavonoid profiles are discussed with respect to substrate preferences of relevant enzymes.     

Antioxidant capacity and phenolic content of spinach as affected by genetics and maturation

Spinach leaves harvested at three maturity stages from eight commercial cultivars (CC) and eight advanced breeding lines (ABL) were evaluated for oxygen radical absorbing capacity (ORAC), total phenolics, and flavonoid composition and content. ABL had higher levels of total phenolics, total flavonoids, and ORAC than CC. Midmaturity spinach leaves had higher levels of total phenolics, total flavonoids, and antioxidant capacity than immature and mature leaves. The contents of individual flavonoids varied in response to maturation, with the predominant glucuronated flavones decreasing and patuletin and spinacetin derivatives increasing. Both total phenolics and total flavonoids correlated well with ORAC (r(xy)() = 0.78 and 0.81, respectively) demonstrating that flavonoids were major contributors to antioxidant capacity. Our results indicate that spinach genotypes should be harvested at the midmaturity stage for consumers to benefit from elevated levels of health promoting flavonoids present in the leaves. Additionally, plant breeders can select for increased phenolic content to increase antioxidant capacity of spinach genotypes.