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Abstract Five previously undescribed acylated pelargonidin 3-sophoroside-5-glucosides (pigments 2–6) were isolated from the red-purple flowers of Iberis umbellata L. 'Candycane Rose' and 'Candycane Red', in addition to a known one (pigment 1). The structures of five undescribed acylated anthocyanins were determined by chemical and spectroscopic methods to be pelargonidin 3- O -[2- O -(2- O -("acyl-A")-β-glucopyranosyl)-6- O -("acyl-B")-β-glucopyranoside]-5- O -[6- O -(malonyl)-β-glucopyranoside], in which the "acyl-A" group was either trans -sinapic (2), trans -ferulic (3), trans -sinapic (4), trans -ferulic (5), or trans -ferulic acid (6), and "acyl-B" was either glucosyl- trans - p -coumaric acid (2), glucosyl- trans - p -coumaric acid (3), trans -feruloyl-glucosyl- trans - p -coumaric acid (4), trans -feruloyl-glucosyl- trans - p -coumaric acid (5), or glucosyl- trans -feruloyl-glucosyl- trans - p -coumaric acid (6). Moreover, three previously undescribed acylated pelargonidin 3-sambubioside-5-glucosides (pigments 7, 8, and 10) and one undescribed acylated pelargonidin 3-(3X-glucosylsambubioside)-5-glucoside (pigment 9) were isolated from the red flowers of Erysimum × cheiri (L.) Crantz 'Aurora' as major anthocyanins. The structures of the three undescribed acylated pelargonidin 3-sambubioside-5-glucosides were determined to be pelargonidin 3- O -[2- O -(2- O -("acyl-C")-β-xylopyranosyl)-6- O -("acyl-D")-β-glucopyranoside]-5- O -(β-glucopyranoside), in which the "acyl-C" group was either non (7), non (8), or trans - p -coumaric acid (10) and "acyl-D" was either trans - p -coumaric (7), trans -ferulic (8), or trans - p -coumaric acid (10). Moreover, a previously undescribed acylated pelargonidin 3-(3X-glucosylsambubioside)-5-glucoside was identified to be pelargonidin 3- O -[2- O -(2- O -(trans - p -coumaroyl)-3- O -(β-glucopyranosyl)-β-xylopyranosyl)-6- O -(trans - p -coumaroyl)-β-glucopyranoside]-5- O -(β-glucopyranoside) (9). In addition, the distribution of anthocyanidins structural elements in 24 Brassicaceous species is compared. Graphical abstract Nine undescribed acylated pelargonidin glycosides together with one known one were isolated from the flowers of Iberis umbellata and Erysimum × cheiri. Image 1 Highlights • Undescribed anthocyanins were isolated from the flowers of Iberis and Erysimum. • The structures were elucidated on the basis of chemical and spectroscopic data. • Major anthocyanins were based on acylated glycosides of pelargonidin. [ABSTRACT FROM AUTHOR]

Abstract: Cultured maize cells habituated to grow in the presence of the cellulose synthesis inhibitor dichlobenil (DCB) have a modified cell wall in which the amounts of cellulose are reduced and the amounts of arabinoxylan increased. This paper examines the contribution of cell wall-esterified hydroxycinnamates to the mechanism of DCB habituation. For this purpose, differences in the phenolic composition of DCB-habituated and non-habituated cell walls, throughout the cell culture cycle and the habituation process were characterized by HPLC. DCB habituation was accompanied by a net enrichment in cell wall phenolics irrespective of the cell culture phase. The amount of monomeric phenolics was 2-fold higher in habituated cell walls. Moreover, habituated cell walls were notably enriched in p-coumaric acid. Dehydrodimers were 5–6-fold enhanced as a result of DCB habituation and the steep increase in 8,5′-diferulic acid in habituated cell walls would suggest that this dehydrodimer plays a role in DCB habituation. In summary, the results obtained indicate that cell wall phenolics increased as a consequence of DCB habituation, and suggest that they would play a role in maintaining the functionality of a cellulose impoverished cell wall. [Copyright &y& Elsevier]

Abstract: Previous studies with transgenic plants have indicated a tobacco anionic peroxidase can confer enhanced resistance to a variety of insects when expressed in different plant species. Tissue that expresses high levels of this enzyme often browns rapidly when damaged. Maize roots damaged under sterile conditions browned and had an anionic peroxidase induced. When introduced biolistically, maize callus transformants expressing a maize peroxidase gene with a predicted isoelectric point of ca. 5.1 produced browner callus compared to a corresponding β-glucuronidase (GUS) transformant as callus aged. Higher production of only one isozyme of ca. pI 4.5 was noted. When the callus was fed to two maize pest caterpillar species, growth rates were slower (as reflected by weights) relative to the GUS callus. Based on examination of published information and electrophoretic properties, this gene appears to code for Px11, a peroxidase isozyme that is primarily produced in root tissue and callus. When sequence of the gene in several inbreds was examined, coding variations were noted, and abilities to utilize ferulic and p-coumaric acids differed. These coding differences may influence the ability of corresponding forms of the peroxidase to promote resistance. In addition to potential use in marker assisted breeding, enhanced expression of this anionic peroxidase through breeding or genetic engineering may lead to enhanced insect or disease resistance. [Copyright &y& Elsevier]

Abstract: The genome of Brachypodium distachyon, also known as purple false brome, was fully sequenced in 2008 largely in response to the demand for a model plant for temperate grasses. A comparative study of the primary cell walls of seedlings of B. distachyon, Hordeum vulgare and Triticum aestivum was carried out. The cell walls of the three species were characterized by similar relative levels of, and developmental changes in, hemicelluloses. The occurrence of (1,3;1,4)-β-d-glucans was correlated with phases of growth involving cell elongation. Expression profiling of the genes involved in (1,3;1,4)-β-d-glucan synthesis (cellulose synthase-like F family (CSLF), CSLH and a putative synthase gene CSLJ) did not show a transcriptional regulation that corresponded to the abundance of (1,3;1,4)-β-d-glucans. CSLF6 transcripts were similarly highly expressed in all three grasses, and were much more abundant than any of the other transcripts. The CSLH transcript was relatively abundant in B. distachyon but almost undetectable in the other species. The deposition of arabinoxylans increased steadily during seedling growth in all three grasses, but they became less substituted and more cross-linked into the wall matrix during cell maturation. Moreover, arabinoxylans in B. distachyon differed from the two other grasses in having a lower degree of arabinose substitution, a higher percentage of ferulic acid in form of dimers and a larger proportion of ester-linked p-coumaric acid. [Copyright &y& Elsevier]

Abstract: p-Coumaric acid is one of the predominant phenolic acids acylating the cell walls of grasses; p-coumarates are mainly esterified by lignins and arabinoxylans. Here we describe the production and characterisation of two monoclonal antibodies against p-coumarates. The 5-O-pCou-Ara(1→4)Xyl was chemically synthesized and conjugated to a carrier protein. Two interesting antibodies were obtained, hereinafter named INRA-COU1 and INRA-COU2. The specificity of these monoclonal antibodies has been evaluated using competitive-inhibition assays with different oligosaccharides and phenolic compounds. INRA-COU1, recognized free p-coumaric acid or p-coumarate esters. INRA-COU1 did not react with any of the other hydroxycinnamic acids and related compounds found in plants. INRA-COU2, only recognizes esterified p-coumarate. These antibodies were used to study the localization of p-coumarates in the cell walls of grasses. Immunocytochemical analyses indicated noticeable amounts of p-coumarate in the cell walls of the aleurone layer of wheat grain, in the epiderm of cereal straw, and in the exoderm of wheat root. The use of these antibodies will contribute to a better understanding of the organisation and developmental dynamics of cell walls in Graminaceae. [Copyright &y& Elsevier]

Abstract: The structures of 11 acylated cyanidin 3-sophoroside-5-glucosides (pigments 1–11), isolated from the flowers of Iberis umbellata cultivars (Cruciferae), were elucidated by chemical and spectroscopic methods. Pigments 1–11 were acylated with malonic acid, p-coumaric acid, ferulic acid, sinapic acid and/or glucosylhydroxycinnamic acids. Pigments 1–11 were classified into four groups by the substitution patterns of the linear acylated residues at the 3-position of the cyanidin. In the first group, pigments 1–3 were determined to be cyanidin 3-O-[2-O-(2-O-(acyl)-β-glucopyranosyl)-6-O-(trans-p-coumaroyl)-β-glucopyranoside]-5-O-[6-O-(malonyl)-β-glucopyranoside], in which the acyl moiety varied with none for pigment 1, ferulic acid for pigment 2 and sinapic acid for pigment 3. In the second one, pigments 4–6 were cyanidin 3-O-[2-O-(2-O-(acyl)-β-glucopyranosyl)-6-O-(4-O-(β-glucopyranosyl)-trans-p-coumaroyl)-β-glucopyranoside]-5-O-[6-O-(malonyl)-β-glucopyranoside], in which the acyl moiety varied with none for pigment 4, ferulic acid for pigment 5 and sinapic acid for pigment 6. In the third one, pigments 7–9 were cyanidin 3-O-[2-O-(2-O-(acyl)-β-glucopyranosyl)-6-O-(4-O-(6-O-(trans-feruloyl)-β-glucopyranosyl)-trans-p-coumaroyl)-β-glucopyranoside]-5-O-[6-O-(malonyl)-β-glucopyranoside], in which the acyl moiety varied with none for pigment 7, ferulic acid for pigment 8, and sinapic acid for pigment 9. In the last one, pigments 10 and 11 were cyanidin 3-O-[2-O-(2-O-(acyl)-β-glucopyranosyl)-6-O-(4-O-(6-O-(4-O-(β-glucopyranosyl)-trans-feruloyl)-β-glucopyranosyl)-trans-p-coumaroyl)-β-glucopyranoside]-5-O-[6-O-(malonyl)-β-glucopyranoside], in which acyl moieties were none for pigment 10 and ferulic acid for pigment 11. The distribution of these pigments was examined in the flowers of four cultivars of I. umbellata by HPLC analysis. Pigment 1 acylated with one molecule of p-coumaric acid was dominantly observed in purple-violet cultivars. On the other hand, pigments (9 and 11) acylated with three molecules of hydroxycinnamic acids were observed in lilac (purple-violet) cultivars as major anthocyanins. The bluing effect and stability on these anthocyanin colors were discussed in relation to the molecular number of hydroxycinnamic acids in these anthocyanin molecules. [Copyright &y& Elsevier]

Abstract: Three acylated cyanidin 3-(3X-glucosylsambubioside)-5-glucosides (1–3) and one non-acylated cyanidin 3-(3X-glucosylsambubioside)-5-glucoside (4) were isolated from the purple-violet or violet flowers and purple stems of Malcolmia maritima (L.) R. Br (the Cruciferae), and their structures were determined by chemical and spectroscopic methods. In the flowers of this plant, pigment 1 was determined to be cyanidin 3-O-[2-O-(2-O-(trans-sinapoyl)-3-O-(β-d-glucopyranosyl)-β-d-xylopyranosyl)-6-O-(trans-p-coumaroyl)-β-d-glucopyranoside]-5-O-[6-O-(malonyl)-(β-d-glucopyranoside) as a major pigment, and a minor pigment 2 was determined to be the cis-p-coumaroyl isomer of pigment 1. In the stems, pigment 3 was determined to be cyanidin 3-O-[2-O-(2-O-(trans-sinapoyl)-3-O-(β-d-glucopyranosyl)-β-d-xylopyranosyl)-6-O-(trans-p-coumaroyl)-β-d-glucopyranoside]-5-O-(β-d-glucopyranoside) as a major anthocyanin, and also a non-acylated anthocyanin, cyanidin 3-O-[2-O-(3-O-(β-d-glucopyranosyl)-β-d-xylopyranosyl)-β-d-glucopyranoside]-5-O-(β-d-glucopyranoside) was determined to be a minor pigment (pigment 4). In this study, it was established that the acylation-enzymes of malonic acid has important roles for the acylation of 5-glucose residues of these anthocyanins in the flower-tissues of M. maritima; however, the similar enzymatic reactions seemed to be inhibited or lacking in the stem-tissues. [Copyright &y& Elsevier]

Abstract: Three acylated cyanidin 3-sambubioside-5-glucosides (1–3) were isolated from the violet-blue flowers of Orychophragonus violaceus, and their structures were determined by chemical and spectroscopic methods. Two of those acylated anthocyanins (1 and 3) were cyanidin 3-O-[2-O-(2-O-(4-O-(6-O-(4-O-(β-d-glucopyranosyl)-trans-caffeoyl)-β-d-glucopyranosyl)-trans-caffeoyl)-β-d-xylopyranosyl)-6-O-(4-O-(β-d-glucopyranosyl)-trans-acyl)-β-d-glucopyranoside]-5-O-(6-O-malonyl-β-d-glucopyranoside)s, in which the acyl groups were p-coumaric acid for 1, and sinapic acid for 3, respectively. The last anthocyanin 2 was cyanidin 3-O-[2-O-(2-O-(4-O-(6-O-(4-O-(β-d-glucopyranosyl)-trans-caffeoyl)-β-d-glucopyranosyl)-trans-caffeoyl)-β-d-xylopyranosyl)-6-O-(4-O-(β-d-glucopyranosyl)-trans-feruloyl)-β-d-glucopyranoside]-5-O-β-d-glucopyranoside. In these flowers, the anthocyanins 2 and 3 were present as dominant pigments, and 1 was obtained in rather small amounts. [Copyright &y& Elsevier]

Two triacylated and tetraglucosylated anthocyanins derived from cyanidin were isolated from the flowers of Ipomoea asarifolia and their structures elucidated using chemical, GC, MS and NMR methods (1H and 13C, TOCSY-1D, DQF-COSY, DIFFNOE and HMBC). These complex pigments were found to consist of cyanidin 3-O-[2-O-(6-O-E-caffeoyl-β-d-glucopyranosyl)]-{6-O-[4-O-(6-O-E-3,5-dihydroxycinnamoyl-β-d-glucopyranosyl)-E-caffeoyl]-β-d-glucopyranosyl}-5-O-β-d-glucopyranoside and cyanidin 3-O-[2-O-(6-O-E-p-coumaroyl-β-d-glucopyranosyl)]-{6-O-[4-O-(6-O-E-p-coumaroyl-β-d-glucopyranosyl)-E-caffeoyl]-β-d-glucopyranosyl}-5-O-β-d-glucopyranoside. [Copyright &y& Elsevier]

The major anthocyanin in the leaves and stems of Arabidopsis thaliana has been isolated and shown to be cyanidin 3-O-[2-O(2-O-(sinapoyl)-β-d-xylopyranosyl)-6-O-(4-O-(β-d-glucopyranosyl)-p-coumaroyl-β-d-glucopyranoside] 5-O-[6-O-(malonyl) β-d-glucopyranoside]. This anthocyanin is a glucosylated version of one of the anthocyanins found in the flowers of the closely related Matthiola incana. [Copyright &y& Elsevier]

The habituation of cultured cells to cellulose biosynthesis inhibitors such as dichlobenil (dichlorobenzonitrile, DCB) has proven a valuable tool to elucidate the mechanisms involved in plant cell wall structural plasticity. Our group has demonstrated that maize cells cope with DCB through a modified cell wall in which cellulose is replaced by a more extensive network of highly cross-linked feruloylated arabinoxylans. In order to gain further insight into the contribution of phenolics to the early remodelling of cellulose-deficient cell walls, a comparative HPLC-PAD analysis was carried out of hydroxycinnamates esterified into nascent and cell wall polysaccharides obtained from non-habituated (NH) and habituated to low DCB concentrations (1.5 μM; H) maize suspension-cultured cells. Incipient DCB-habituated cell walls showed significantly higher levels of esterified ferulic acid and p -coumaric acid throughout the culture cycle. In terms of cell wall fortification, ferulic acid is associated to arabinoxylan crosslinking whereas the increase of p -coumaric suggests an early lignification response. As expected, the level of hydroxycinnamates esterified into nascent polysaccharides was also higher in DCB-habituated cells indicating an overexpression of phenylpropanoid pathway. Due to their key role in cell wall strengthening, special attention was paid into the dimerization pattern of ferulic acid. A quantitative comparison of diferulate dehydrodimers (DFAs) between cell lines and cell compartments revealed that an extra dimerization took place in H cells when both nascent and mature cell wall polysaccharides were analysed. In addition, qualitative differences in the ferulic acid coupling pattern were detected in H cells, allowing us to suggest that 8-O-4′-DFA and 8-5′-DFA featured the ferulic acid dimerization when it occurred in the protoplasmic and cell wall fractions respectively. Both qualitative and quantitative differences in the phenolic profile between NH and H cells point to a regioselectivity in the ferulate dehydrodimerization. Structural model of the primary cell wall of dichlobenil-habituated maize suspension-cultured cells showing the interactions between cellulose, arabinoxylans and phenolic compounds. Image 1 • Phenolic profile of DCB-habituated cells shows quantitative and qualitative features. • Intra-protoplasmic and cell wall extra dimerization occurs in DCB-habituated cells. • 8-O-4′-DFA and 8-5′-DFA increases during DCB-habituation. • A regioselectivity in the ferulate dehydrodimerization is proposed. [ABSTRACT FROM AUTHOR]

The brown to black coloration found in plants is due to the melanins, which have been relatively poorly investigated among the plant pigments. The aim of this work was to study the dark pigment extracted from the black oat hull with respect to composition and structure. Ultraviolet-visible (UV-Vis) spectroscopy, electron paramagnetic resonance (EPR) spectroscopy, matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS) and Fourier transform infrared (FT-IR) spectroscopy were applied for the characterization of the pigment. UV-Vis spectroscopy revealed that the extracted material displays a broadband, structureless absorption profile a common feature of melanins. MALDI-TOF MS measurements demonstrated that oat melanin is a homopolymer built up from p-coumaric acid and consists mainly of low molecular weight (527-1499 Da) oligomers of 3-9 monomer units. The tetramer oligomer proved to be dominant. The results of the FT-IR analysis indicated that oat melanin is a fully conjugated aromatic system containing tetrasubstituted aromatic rings linked by CC coupling. The in vitro preparation of melanin from p-coumaric acid by horseradish peroxidase was performed for comparison. The resulting polymer consisted of oligomers of 4-9 monomer units similarly to those in oat melanin. However, the building blocks proved to be connected to each other via COC linkages in contrast with the CC linkages in oat melanin., (Copyright © 2016 Elsevier Ltd. All rights reserved.)