An active hAT transposable element causing bud mutation of carnation by insertion into the flavonoid 3'-hydroxylase gene.

The molecular mechanisms underlying spontaneous bud mutations, which provide an important breeding tool in carnation, are poorly understood. Here we describe a new active hAT type transposable element, designated Tdic101, the movement of which caused a bud mutation in carnation that led to a change of flower color from purple to deep pink. The color change was attributed to Tdic101 insertion into the second intron of F3'H, the gene for flavonoid 3'-hydroxylase responsible for purple pigment production. Regions on the deep pink flowers of the mutant can revert to purple, a visible phenotype of, as we show, excision of the transposable element. Sequence analysis revealed that Tdic101 has the characteristics of an autonomous element encoding a transposase. A related, but non-autonomous element dTdic102 was found to move in the genome of the bud mutant as well. Its mobilization might be the result of transposase activities provided by other elements such as Tdic101. In carnation, therefore, the movement of transposable elements plays an important role in the emergence of a bud mutation.

Reverted glutathione S-transferase-like genes that influence flower color intensity of carnation (Dianthus caryophyllus L.) originated from excision of a transposable element.

A glutathione S-transferase-like gene, DcGSTF2, is responsible for carnation (Dianthus caryophyllus L.) flower color intensity. Two defective genes, DcGSTF2mu with a nonsense mutation and DcGSTF2-dTac1 containing a transposable element dTac1, have been characterized in detail in this report. dTac1 is an active element that produces reverted functional genes by excision of the element. A pale-pink cultivar 'Daisy' carries both defective genes, whereas a spontaneous deep-colored mutant 'Daisy-VPR' lost the element from DcGSTF2-dTac1. This finding confirmed that dTac1 is active and that the resulting reverted gene, DcGSTF2rev1, missing the element is responsible for this color change. Crosses between the pale-colored cultivar '06-LA' and a deep-colored cultivar 'Spectrum' produced segregating progeny. Only the deep-colored progeny had DcGSTF2rev2 derived from the 'Spectrum' parent, whereas progeny with pale-colored flowers had defective forms from both parents, DcGSTF2mu and DcGSTF2-dTac1. Thus, DcGSTF2rev2 had functional activity and likely originated from excision of dTac1 since there was a footprint sequence at the vacated site of the dTac1 insertion. Characterizing the DcGSTF2 genes in several cultivars revealed that the two functional genes, DcGSTF2rev1 and DcGSTF2rev2, have been used for some time in carnation breeding with the latter in use for more than half a century.

Post-stress metabolism involves umbelliferone production in anthocyanin-producing and nonproducing cells of Glehnia littoralis suspension cultures.

The effects of yeast extract on the accumulation of transcripts of phenylalanine ammonia-lyase (PAL, EC 4.1.3.5) and chalcone synthase (CHS, EC 2.3.1.74), PAL and CHS enzyme activity and furanocoumarin and anthocyanin metabolites over a 48 h period were studied in anthocyanin-producing (Violet) and non-producing (White) cell suspension cultures of Glehnia littoralis. In the course of this period, umbelliferone, which had not been detected earlier, was detected in the culture medium of the Violet as well as White cells. In White cells, the PAL transcript accumulation and an increase in PAL activity were in good agreement with the level of umbelliferone, and was followed by the induction of bergapten. In the case of the Violet cells, the accumulation of PAL and CHS transcripts, and the increases in PAL and CHS enzyme activity as well as the anthocyanin level, all of which were highly expressed in nontreated cells, were temporarily suppressed. However, the suppression of the PAL transcript and PAL activity was not as great as that of the CHS transcript accumulation and CHS activity, in which a sharp transient increase of umbelliferone production soon after elicitation appears to be a factor.

Plant biochemistry: anthocyanin biosynthesis in roses.

Anthocyanin is the principal pigment in flowers, conferring intense red-to-blue cyanic colours on petals and helping to attract pollinators. Its biosynthesis involves glycosylation steps that are important for the stability of the pigment and for its aqueous solubility in vacuoles. Here we describe anthocyanin biosynthesis in roses (Rosa hybrida), which is unlike the pathway used in other flowers in that it relies on a single enzyme to achieve glycosylation at two different positions on the precursor molecule. Phylogenetic analysis also indicates that this previously unknown glucosyltransferase enzyme may be unique to roses, with glycosylation having apparently evolved into a single stabilizing step in other plants.

Putative cis-elements in the promoter region of the carrot phenylalanine ammonia-lyase gene induced during anthocyanin synthesis.

Deletion mutants of the carrot phenylalanine ammonia-lyase gene promoter were used to survey cis-elements for their effect on expression of promoter activity by transient expression. Two putative cis-elements were required to give full activity, but a third might be the most important in regulation of the promoter by 2,4-dichlorophenoxyacetic acid.

Excision of transposable elements from the chalcone isomerase and dihydroflavonol 4-reductase genes may contribute to the variegation of the yellow-flowered carnation (Dianthus caryophyllus).

In the "Rhapsody" cultivar of the carnation, which bears white flowers variegated with red flecks and sectors, a transposable element, dTdic1, belonging to the Ac/Ds superfamily, was found within the dihydroflavonol 4-reductase (DFR) gene. The red flecks and sectors of "Rhapsody" may be attributable to a reversion to DFR activity after the excision of dTdic1. The yellow color of the carnation petals is attributed to the synthesis and accumulation of chalcone 2'-glucoside. In several of the carnation cultivars that bear yellow flowers variegated with white flecks and sectors, both the chalcone isomerase (CHI) and DFR genes are disrupted by dTdic1.

Antitumor activity of compounds isolated from leaves of Eriobotrya japonica.

In a search for possible antitumor agents from natural sources, megastigmane glycosides and polyphenolic constituents isolated from the leaves of Eriobotrya japonica (Rosaceae) were found to inhibit the 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced activation of Epstein-Barr virus early antigen in Raji cells. Roseoside and procyanidin B-2 were among the active compounds found in an in vitro assay; these compounds were further assessed for antitumor activity in vivo in a two-stage carcinogenesis assay on mouse skin. Roseoside significantly delayed carcinogenesis induced by peroxynitrite (initiator) and TPA (promoter), and its potency was comparable to that of a green tea polyphenol, (-)-epigallocatechin 3-O-gallate, in the same assay.