Medicago glucosyltransferase UGT72L1: potential roles in proanthocyanidin biosynthesis.

In the first reaction specific for proanthocyanidin (PA) biosynthesis in Arabidopsis thaliana and Medicago truncatula, anthocyanidin reductase (ANR) converts cyanidin to (-)-epicatechin. The glucosyltransferase UGT72L1 catalyzes formation of epicatechin 3'-O-glucoside (E3'OG), the preferred substrate for MATE transporters implicated in PA biosynthesis in both species. The mechanism of PA polymerization is still unclear, but may involve the laccase-like polyphenol oxidase TRANSPARENT TESTA 10 (TT10).

Choline metabolism in glycinebetaine accumulating and non-accumulating near-isogenic lines of Zea mays and Sorghum bicolor.

Glycinebetaine (GB) is a compatible solute that is accumulated by some plant species, especially under conditions leading to tissue osmotic stress. Genetic modification for accumulation of GB in an attempt to produce more stress tolerant plants has been a focus for several groups in recent years. However, attempts to increase tissue GB concentrations have been unsuccessful, with many transgenic lines accumulating far lower concentrations than naturally-occurring GB accumulators.

A WD40 repeat protein from Medicago truncatula is necessary for tissue-specific anthocyanin and proanthocyanidin biosynthesis but not for trichome development.

WD40 repeat proteins regulate biosynthesis of anthocyanins, proanthocyanidins (PAs), and mucilage in the seed and the development of trichomes and root hairs. We have cloned and characterized a WD40 repeat protein gene from Medicago truncatula (MtWD40-1) via a retrotransposon-tagging approach. Deficiency of MtWD40-1 expression blocks accumulation of mucilage and a range of phenolic compounds, including PAs, epicatechin, other flavonoids, and benzoic acids, in the seed, reduces epicatechin levels without corresponding effects on other flavonoids in flowers, reduces isoflavone levels in roots, but does not impair trichome or root hair development.

The LAP1 MYB transcription factor orchestrates anthocyanidin biosynthesis and glycosylation in Medicago.

MYB transcription factors help to control anthocyanin biosynthesis in plants, and ectopic expression of the Arabidopsis Production of Anthocyanin Pigment 1 (PAP1) transcription factor activates the anthocyanin pathway in tobacco, suggesting the general utility of such factors for metabolic engineering of anthocyanins and anthocyanin-derived compounds such as proanthocyanidins (condensed tannins). However, PAP1 does not activate anthocyanin biosynthesis in the model legume Medicago truncatula or in alfalfa (Medicago sativa). A related Legume Anthocyanin Production 1 (LAP1) gene was identified from the genome of M.

Transcript and proteomic analysis of developing white lupin (Lupinus albus L.) roots.

Background: White lupin (Lupinus albus L.) roots efficiently take up and accumulate (heavy) metals, adapt to phosphate deficiency by forming cluster roots, and secrete antimicrobial prenylated isoflavones during development. Genomic and proteomic approaches were applied to identify candidate genes and proteins involved in antimicrobial defense and (heavy) metal uptake and translocation.

A transcript profiling approach reveals an epicatechin-specific glucosyltransferase expressed in the seed coat of Medicago truncatula.

Expression of the Arabidopsis TRANSPARENT TESTA 2 (TT2) MYB family transcription factor leads to massive accumulation of proanthocyanidins (PAs) in hairy roots of Medicago truncatula. Microarray analysis showed that TT2 induces genes for flavonoid/PA biosynthesis, transcription factors, and a large number of genes of unknown function. A second microarray dataset identified genes that were preferentially expressed in the M.

Early steps in proanthocyanidin biosynthesis in the model legume Medicago truncatula.

Oligomeric proanthocyanidins (PAs) composed primarily of epicatechin units accumulate in the seed coats of the model legume Medicago truncatula, reaching maximal levels at around 20 d after pollination. Genes encoding the single Medicago anthocyanidin synthase (ANS; EC 1.14.

Insertional inactivation of the methionine s-methyltransferase gene eliminates the s-methylmethionine cycle and increases the methylation ratio.

Methionine (Met) S-methyltransferase (MMT) catalyzes the synthesis of S-methyl-Met (SMM) from Met and S-adenosyl-Met (Ado-Met). SMM can be reconverted to Met by donating a methyl group to homocysteine (homo-Cys), and concurrent operation of this reaction and that mediated by MMT sets up the SMM cycle. SMM has been hypothesized to be essential as a methyl donor or as a transport form of sulfur, and the SMM cycle has been hypothesized to guard against depletion of the free Met pool by excess Ado-Met synthesis or to regulate Ado-Met level and hence the Ado-Met to S-adenosylhomo-Cys ratio (the methylation ratio).

Characterization of betaines using electrospray MS/MS.

Betaines are an important class of naturally occurring compounds that function as compatible solutes or osmoprotectants. Because of the permanent positive charge on the quaternary ammonium moiety, mass spectrometric analysis has been approached by desorption methods, including fast atom bombardment and plasma desorption mass spectrometry. Here we show that electrospray ionization MS gives comparable results to plasma desorption MS for a range of authentic betaine standards and betaines purified from plant extracts by ion exchange chromatography.