Anthocyanin Accumulation Patterns Research Articles

Effects of Temperature on the Pattern of Anthocyanin Accumulation in Seedlings of Polygonum cuspidatum

seedling. Anthocyanin accumulated first in the lower part of hypocotyls and then the site of accumulation gradually extended toward the upper part of hypocotyls when seedlings were irradiated with white light (WL) at 25 C. Etiolated seedlings accumulated anthocyanin only in the upper parts (hook and cotyledons) when the seedlings were irradiated with WL at 5 C. De-etiolated seedlings that had been pre-irradiated with WL for 1 day at 25 C accumulated anthocyanin both in upper and lower parts of the seedlings when the seedlings were irradiated with WL at 5 C. Spectral sensitivity was dependent on the temperature during irradiation. Red light (R), blue light (B), and near ultra-violet light (NUV) induced the accumulation of anthocyanin at 5 C but only NUV was effective in inducing the accumulation of anthocyanin at 25 C. Dichlorophenyl dimethylurea (DCMU) inhibited WL-induced anthocyanin accumulation but did not NUV-induced anthocyanin accumulation at 25 C. However, sucrose promoted NUV action at 25 C, indicating that photosynthesis can promote NUV-induced anthocyanin accumulation. Distribution of phytochrome in etiolated seedlings, that was examined by spectrophotometry, was similar to the distribution of anthocyanin at 5 C. Furthermore, phytochrome remained after 48 hr irradiation with WL at 5 C although phytochrome was rapidly degraded at 25 C.

Changes in Anthocyanin Content and Composition of Developing Storage Root of Purple-Fleshed Sweet Potato(Ipomoea batatas(L.) Lam).

The changes in the content and composition of anthocyanin in the developing storage root of 10 purple-fleshed sweet potato clones were investigated in order to elucidate the pattern of anthocyanin accumulation between clones with a high and low anthocyanin content. At the 3rd week after transplanting, in most clones, anthocyanins were detected in the young thick roots that had the potential to develop into storage roots. The pattern of anthocyanin accumulation was characterized into three distinctive phases: (1) an initial rapid increase during the 3rd to 6th week, (2) no change or a slight decrease during the 6th to 12th week, and (3) a slight increase during the 12th to 17th week. Northern blot analysis indicated that mRNA levels of dihydroflavonol 4-reductase (DFR), one of the key enzymes of the anthocyanin biosynthetic pathway, was expressed throughout the stage of storage root development. In addition, DFR mRNA appeared to be the most abundant at the 6th week, and reduced an the 9th week, which coincides with the change in anthocyanin content. These results suggest that anthocyanin is synthesized throughout the stage of storage root development, but not in a steady manner, and that anthocyanin accumulation in sweet potato could be related to the transcriptional regulation of anthocyanin biosynthetic genes. The rate of increase in anthocyanin content during the 3rd to 6th week was significantly higher in clones with a high anthocyanin content than in clones with a low anthocyanin content. It may be possible to screen clones after the 9th week when the percentage of peonidin, which is an index for anthocyanin composition in purple-fleshed sweet potato, become constant, and the large storage roots (more than 20 mm in diameter) are produced in most clones.

Anthocyanin regulatory gene expression in transgenic white clover can result in an altered pattern of pigmentation

This study presents the first evidence of heterologous anthocyanin regulatory genes altering anthocyanin expression in stably transformed leguminous plants. Two families of anthocyanin regulatory genes, myc (delila, B-Peru) and myb (myb.Ph2, C1), are involved in the activation of the phenylpropanoid pathway. White clover (Trifolium repens cv. Haifa) plants were transformed with dicotyledonous and monocotyledonous myb or myc genes. Some of these transformed plants exhibited enhanced anthocyanin accumulation in a range of tissues. One plant, transformed with the B-Peru gene driven by the Cauliflower Mosaic Virus 35S promoter, displayed a unique pattern of anthocyanin accumulation in the leaf. The accumulation of anthocyanin in this plant was closely associated with the crescent of leaves, which is normally white. The red pigmentation declined in intensity in the oldest leaf stage. The B-Peru message was detected in all leaf stages of this white clover plant. This anthocyanin pattern was shown to be heritable.

538 Use of Lysophoshatidylethanolamine (LPE), a Natural Lipid, to Accelerate Ripening and Enhance Shelf Life of Cranberry Fruit

Recent studies from our laboratory have demonstrated that lysophoshatidylethanolamine (LPE) is able to accelerate fruit ripening while at the same time promoting shelf life. LPE is a natural lipid and is commercially extracted from egg yolks and soybeans. We studied the influence of LPE on the pattern of anthocyanin accumulation and storage quality of cranberry fruit (Vaccinium macrocarpon Ait. cultivar Stevens). For this purpose 2 x 2-m plots were established in cranberry beds at two separate locations near Wisconsin Rapids. Experiments were conducted in 1997 and 1998 seasons. Plots were sprayed with LPE (extracted from egg yolk and soybean) 3 to 4 weeks before harvest. Spray solution included 200 ppm LPE, 3% ethanol, and 0.1% detergents (either Tergitol or Sylguard). Fruit samples were taken from a part in the plot periodically to determine the changes in the fruit. The rest of the plots were commercially wet harvested with a machine and stored in cold storage. Marketable fruit were counted at various times of cold storage to determine effect of LPE on shelf life of cranberries. In general, application of LPE from both sources resulted in 20% to 35 % increase in fruit anthocyanin contents. Also LPE treatment resulted in 10% to 20% increase in marketable fruit in cold storage. A postharvest dip of cranberry fruit with 50 ppm LPE solution for 15 min also resulted in about a 20% to 30% increase in marketable berries during cold storage. The results of this study shows that pre- and postharvest applications of LPE can add value to cranberry crop including better and more uniform colored fruit, enhance self life, and earlier harvest.

Flavonoid metabolism in Forsythia flowers

The flavonoid pathway metabolism was studied in petals and sepals of Forsythia X intermedia cv. ‘Spring Glory’. The activities of the flavonoid enzymes chalcone synthase (CHS), flavanone 3-hydroxylase (FHT) and flavonol synthase (FLS) were measured. The dihydroflavonol 4-reductase (DFR) role was also studied by comparing flavonoid accumulation in transgenic plants for a heterologous DFR gene and wild-type F. X intermedia cv. ‘Spring Glory’, already investigated for DFR gene expression and activity. HPLC analyses complemented enzymatic investigations, showing that: (i) rutin (quercetin 3-rutinoside) is the major flavonol accumulated in petals and sepals (ca. 90% of the flavonol pool) and; (ii) quercetin and cyanidin derivatives are the exclusive flavonols and anthocyanins in sepals, respectively. The overall data demonstrated that the flavonoid pathway in F. X intermedia flower organs leads to the major accumulation of 3′,4′-dihydroxylated compounds, and that 3′-hydroxylation of the B-ring occurs mainly at flavonoid intermediate stage(s). Comparative HPLC analyses of F. X intermedia cv. ‘Spring Glory’ and three other genotypes (F. giraldiana, F. X intermedia ‘Korfor’ Goldzauber® and F. ovata ‘Robusta’) confirmed the major production of flavonols by Forsythia flavonoid metabolism and suggested a method for screening Forsythia genotypes based on anthocyanin accumulation pattern in sepals.

Leafy Cotyledon Mutants of Arabidopsis.

We have previously described a homeotic leafy cotyledon (lec) mutant of Arabidopsis that exhibits striking defects in embryonic maturation and produces viviparous embryos with cotyledons that are partially transformed into leaves. In this study, we present further details on the developmental anatomy of mutant embryos, characterize their response to abscisic acid (ABA) in culture, describe other mutants with related phenotypes, and summarize studies with double mutants. Our results indicate that immature embryos precociously enter a germination pathway after the torpedo stage of development and then acquire characteristics normally restricted to vegetative parts of the plant. In contrast to other viviparous mutants of maize (vp1) and Arabidopsis (abi3) that produce ABA-insensitive embryos, immature lec embryos are sensitive to ABA in culture. ABA is therefore necessary but not sufficient for embryonic maturation in Arabidopsis. Three other mutants that produce trichomes on cotyledons following precocious germination in culture are described. One mutant is allelic to lec1, another is a fusca mutant (fus3), and the third defines a new locus (lec2). Mutant embryos differ in morphology, desiccation tolerance, pattern of anthocyanin accumulation, presence of storage materials, size and frequency of trichomes on cotyledons, and timing of precocious germination in culture. The leafy cotyledon phenotype has therefore allowed the identification of an important network of regulatory genes with overlapping functions during embryonic maturation in Arabidopsis.

Cloning of cDNA coding for dihydroflavonol-4-reductase (DFR) and characterization of dfr expression in the corollas of Gerbera hybrida var. Regina (Compositae).

We are approaching corolla differentiation in Compositae by studying the regulation of flavonoid pathway genes during inflorescence development in gerbera. We have cloned a dfr cDNA from a ray floret corolla cDNA library of Gerbera hybrida var. Regina by a PCR technique based on homologies found in genes isolated from other plant species. The functionality of the clone was tested in vivo by complementing the dihydrokaempferol accumulating petunia mutant line RL01. By Southern blot analysis, G. hybrida var. Regina was shown to harbour a small family of dfr genes, one member of which was deduced to be mainly responsible for the DFR activity in corolla. Dfr expression in corolla correlates with the anthocyanin accumulation pattern: it is basipetally induced, epidermally specific and restricted to the ligular part of corolla. By comparing the dfr expression in different floret types during inflorescence development, we could see that dfr expression reflects developmental schemes of the outermost ray and trans florets, contrasted with that of the disc florets.