To evaluate the physiological significance of cyclic electron flow around photosystem (PS) I, we used a reverse genetic approach to focus on 11 chloroplast genes that encode homologs mitochondrial complex I subunits (ndhA-K). Since their discovery, exact function respiratory components in plant chloroplasts has been matter discussion. We disrupted one these (ndhB) tobacco by transformation. Analysis transient increase chlorophyll fluorescence after actinic light illumination and redox...

The tropane alkaloid scopolamine is a medicinally important anticholinergic drug present in several solanaceous plants. Hyoscyamine 6 beta-hydroxylase (EC 1.14.11.11) catalyzes the oxidative reactions biosynthetic pathway leading from hyoscyamine to scopolamine. We introduced hydroxylase gene Hyoscyamus niger under control of cauliflower mosaic virus 35S promoter into hyoscyamine-rich Atropa belladonna by use an Agrobacterium-mediated transformation system. A transgenic plant that...

Two nuclear genes, Nic1 and Nic2, regulate nicotine levels in tobacco. nic1 nic2 are semidominant mutations Burley 21 that reduce leaf the activities of multiple enzymes pathway simultaneously increase polyamine cultured roots. Cultured roots homozygous for both were used to isolate two cDNAs by subtraction hybridization; transcript these much lower mutant than wild-type The A411 gene encodes a 41-kD protein with considerable homology mammalian spermidine synthase, whereas A622 35-kD high...

Crop loss due to soil salinization is an increasing threat agriculture worldwide. This review provides overview of cellular and physiological mechanisms in plant responses salt. We place a time- tissue-dependent context ...Read More

Plant alkaloids, one of the largest groups natural products, provide many pharmacologically active compounds. Several genes in biosynthetic pathways for scopolamine, nicotine, and berberine have been cloned, making metabolic engineering these alkaloids possible. Expression two branching-point enzymes was engineered: putrescine N -methyltransferase (PMT) transgenic plants Atropa belladonna Nicotiana sylvestris ( S )-scoulerine 9- O (SMT) cultured cells Coptis japonica Eschscholzia californica...

Roots of several solanaceous plants produce anticholinergic alkaloids, hyoscyamine and scopolamine. Hyoscyamine GB-hydroxylase, a2-oxoglutarate-dependent dioxygenase (EC 1.14.11.11), catalyzes hydroxylation in the biosynthetic pathway leading to scopolamine.We report here on isolation cDNA clones encoding hydroxylase from a library made mRNA cultured roots Hyoscyamus niger.The was screened with three synthetic oligonucleotides that encode amino acid sequences internal peptide fragments...

Mutations in the Agr locus of Arabidopsis thaliana impair root gravitropic response. Root growth agr mutants is moderately resistant to ethylene and an auxin transport inhibitor. Vertically placed roots grow into agar medium containing IAA or naphthalene-1-acetic acid, but not 2,4-D. Positional cloning showed that AGR encodes a root-specific member novel membrane-protein family with limited homology bacterial transporters.

Hyoscyamine 6 beta-hydroxylase (H6H; EC 1.14.11.11) catalyzes the first reaction in biosynthetic pathway from hyoscyamine to scopolamine several solanaceous plants. Four monoclonal antibodies were raised against H6H purified cultured roots of Hyoscyamus niger. The IgG1 antibody mAb5 inhibited activities present cell-free extracts H. niger and specifically recognized 38-40-kDa proteins six different scopolamine-producing plant species Western blot analysis after sodium dodecyl sulfate...

Root cultures of various solanaceous plants grow well in vitro and produce large amounts tropane alkaloids. Enzyme activity that converts hyoscyamine to 6beta-hydroxyhyoscyamine is present cell-free extracts from cultured roots Hyoscyamus niger L. The enzyme 6beta-hydroxylase was purified 3.3-fold characterized. hydroxylation reaction has absolute requirements for hyoscyamine, 2-oxoglutarate, Fe(2+) ions molecular oxygen, ascorbate stimulates this reaction. Only the l-isomer serves as a...

1. BENTLEY, J. A. 1961. The states of auxin in the plant. In: Handbuch d. Pflanzenphysiologie. W. Ruhland, ed. Springer-Verlag, Berlin, Germany. vol XIV, pp 609-19. 2. CUMMING, B. G. 1959. control growth and development red clover (Trifolium patense L.). III. Endogenous diffusible auxin. Can. Botany 37: 1049-62. 3. MILLER, S. AND GORDON. 1962. Auxin relations illuminated shoots. Plant Physiol. xvi-xvii. 4. NAKAMURA, T., H. ISHII, T. YAMAKI. Intercellular localization native Avena coleoptile....

S-adenosyl-L-methionine:3'-hydroxy-N-methylcoclaurine 4'-O-methyltransferase (4'-OMT) catalyzes the conversion of 3'-hydroxy-N-methylcoclaurine to reticuline, an important intermediate in synthesizing isoquinoline alkaloids. In earlier step biosynthetic pathway another O-methyltransferase, S-adenosyl-L-methionine:norcoclaurine 6-O-methyltransferase (6-OMT), methylation 6-hydroxyl group norcoclaurine. We isolated two kinds cDNA clones that correspond internal amino acid sequences a...

Nicotine alkaloids are synthesized in the root of Nicotiana species, and their synthesis increases after insect attack, wounding jasmonate treatment leaf. Putrescine N-methyltransferase (PMT) catalyzes first committed step nicotine biosynthesis. The expression patterns three sylvestris PMT genes (NsPMT1, NsPMT2, NsPMT3) reported this study. Transcripts NsPMT were detected only root, up-regulated by methyl treatment. When 5'-flanking regions NsPMT1, NsPMT3 fused independently to...

In several solanaceous plants, hyoscyamine is first hydroxylated at the 6β‐position, and then epoxidized to scopolamine. We expressed 6β‐hydroxylase (H6H) in Escherichia coli as a fusion protein with maltose‐binding protein. The crude cell extract from bacterium that soluble showed strong hydroxylase activity weak epoxidase activity. When 100 μM of was fed recombinant bacterium, alkaloid converted 6β‐hydroxyhyoscyamine, scopolamine, which almost only found culture after one week. Therefore,...

The cDNAs encoding putrescine N-methyltransferase (PMT), which catalyzes the S-adenosylmethionine-dependent N-methylation of at first committed step in biosynthetic pathways tropane alkaloids, were isolated from Atropa belladonna and Hyoscyamus niger. These PMTs, however, lacked N-terminal tandem repeat arrays previously found Nicotiana PMTs. AbPMT1 RNA was much more abundant root A. than AbPMT2 RNA. 5′-flanking region gene fused to β-glucuronidase (GUS) reporter transferred belladonna....

Hyoscyamine 6 beta-hydroxylase, a 2-oxoglutarate-dependent dioxygenase that catalyzes the hydroxylation of l-hyoscyamine to beta-hydroxyhyoscyamine in biosynthetic pathway leading scopolamine [Hashimoto, T. & Yamada, Y. (1986) Plant Physiol. 81, 619-625] was purified 310-fold from root cultures Hyoscyamus niger L. The enzyme has an average Mr 41,000 as determined by gel filtration on Superose 12 and exhibited maximum activity at pH 7.8 l-Hyoscyamine 2-oxoglutarate are required for activity,...

We have isolated, cloned and characterized three cDNAs two genomic DNAs corresponding to the mRNAs genes for horseradish (Armoracia rusticana) peroxidase isoenzyme C (HPR C). The amino acid sequence of HRP C1, deduced from nucleotide one cDNA clone, pSK1, contained same primary as that purified enzyme established by Welinder [FEBS Lett. 72, 19-23 (1976)] with additional sequences at N terminal. All inserts in clones, pSK2 pSK3, coded size peptide (308 residues) if these are processed way,...

Specific plant species produce unique isoquinoline alkaloids (IQAs); however, the mechanism of their evolution and regulation biosynthesis are largely unknown. We report here isolation a novel basic helix–loop–helix protein, CjbHLH1, from IQA-producing Coptis japonica. A BLAST search indicated that CjbHLH1 homologs were only found in IQAs. Transient RNA interference (RNAi) overexpression C. japonica protoplasts revealed activity transcription IQA biosynthetic genes, little genes involved...