Differential regulation and distribution of Acridone Synthase in Ruta graveolens in honour of Professor G. H. Neil Towers 75th birthday

Junghanns, Kay T; Kneusel, Richard E.; Gröger, D.; Matern, Ulrich

doi:10.1016/s0031-9422(98)00104-6

Cited by 32 publications

(25 citation statements)

References 23 publications

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“…By contrast, protoberberine alkaloid biosynthesis and accumulation in T. flavum roots appear to occur in the same cell, although we cannot rule out the possibility that products are translocated between endodermis and pericycle or transported to other organs. The formation and storage of acridone alkaloids were also associated with endodermis in Ruta graveolens (Junghanns et al, 1998). Localization of alkaloid biosynthetic enzymes to endodermis and pericycle provides efficient access to amino acid precursors from the phloem and to vascular conduits for the systemic transport of metabolic products.…”

Section: Discussionmentioning

confidence: 98%

Cell Type–Specific Localization of Transcripts Encoding Nine Consecutive Enzymes Involved in Protoberberine Alkaloid Biosynthesis

2005

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Molecular clones encoding nine consecutive biosynthetic enzymes that catalyze the conversion of L-dopa to the protoberberine alkaloid (S)-canadine were isolated from meadow rue (Thalictrum flavum ssp glaucum). The predicted proteins showed extensive sequence identity with corresponding enzymes involved in the biosynthesis of related benzylisoquinoline alkaloids in other species, such as opium poppy (Papaver somniferum). RNA gel blot hybridization analysis showed that gene transcripts for each enzyme were most abundant in rhizomes but were also detected at lower levels in roots and other organs. In situ RNA hybridization analysis revealed the cell type-specific expression of protoberberine alkaloid biosynthetic genes in roots and rhizomes. In roots, gene transcripts for all nine enzymes were localized to immature endodermis, pericycle, and, in some cases, adjacent cortical cells. In rhizomes, gene transcripts encoding all nine enzymes were restricted to the protoderm of leaf primordia. The localization of biosynthetic gene transcripts was in contrast with the tissue-specific accumulation of protoberberine alkaloids. In roots, protoberberine alkaloids were restricted to mature endodermal cells upon the initiation of secondary growth and were distributed throughout the pith and cortex in rhizomes. Thus, the cell type-specific localization of protoberberine alkaloid biosynthesis and accumulation are temporally and spatially separated in T. flavum roots and rhizomes, respectively. Despite the close phylogeny between corresponding biosynthetic enzymes, distinct and different cell types are involved in the biosynthesis and accumulation of benzylisoquinoline alkaloids in T. flavum and P. somniferum. Our results suggest that the evolution of alkaloid metabolism involves not only the recruitment of new biosynthetic enzymes, but also the migration of established pathways between cell types.

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Section: Discussionmentioning

confidence: 98%

Cell Type–Specific Localization of Transcripts Encoding Nine Consecutive Enzymes Involved in Protoberberine Alkaloid Biosynthesis

2005

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“…3) suggest another peculiar function. It must be recalled in this context that the elicitation of Ruta graveolens cells does not affect the flavonoid pathway (Junghanns et al 1998), but the cell cultures accumulate coumarins and acridone alkaloids under these conditions. While the involvement of Rg4CL1 in acridone formation was ruled out, the expression of this transcript in shoot and flower tissues of Ruta plants (Fig.…”

Section: Discussionmentioning

confidence: 99%

“…Total RNA was therefore isolated from Ruta cells treated for 3 h (Junghanns et al 1998) with yeast extract, the cDNA synthesized and used as PCR template after hybridization with 10-fold excess poly(A) + RNA from untreated control cells. Initial amplifications which employed degenerated oligonucleotide primers inferred from conserved boxes I (SSGTTGLPKGV) and II (GEICIRG) flanking the adenylation domain in CoA-ligases failed.…”

Section: Pcr-based Cloning and Sequence Analysismentioning

confidence: 99%

Unusually divergent 4-coumarate:CoA-ligases from Ruta graveolens L.

et al. 2008

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Most angiosperms encode a small family of 4-coumarate:CoA-ligases (4CLs) activating hydroxycinnamic acids for lignin and flavonoid pathways. The common rue, Ruta graveolens L., additionally produces coumarins by cyclization of the 4-coumaroyl moiety, possibly involving the CoA-ester, as well as acridone and furoquinoline alkaloids relying on (N-methyl)anthraniloyl-CoA as the starter substrate for polyketide synthase condensation. The accumulation of alkaloids and coumarins, but not flavonoids, was enhanced in Ruta graveolens suspension cultures upon the addition of fungal elicitor. Total RNA of elicitor-treated Ruta cells was used as template for RT-PCR amplification with degenerate oligonucleotide primers inferred from conserved motifs in AMP-binding proteins, and two full-size cDNAs were generated through RACE and identified as 4-coumarate:CoA-ligases, Rg4CL1 and Rg4CL2, by functional expression in yeast cells. The recombinant enzymes differed considerably in their preferential affinities to cinnamate (Rg4CL1) or ferulate (RgCL2) besides 4-coumarate, but did not activate hydroxybenzoic or (N-methyl)anthranilic acid. Most notably, the Rg4CL1 polypeptide included an N-terminal extension suggesting a chloroplast transit peptide. The genes were cloned and revealed four exons, separated by 1056, 94 and 54 bp introns for RgCL1, while Rg4CL2 was composed of five exons interupted by four introns from 113 to 350 bp, and the divergent heritage of these genes was substantiated by phylogenetic analysis. Both genes were expressed in shoot, leaf and flower tissues of adult Ruta plants with preference in shoot and flower, whereas negligible expression occurred in the root. However, Rg4CL1 was expressed much stronger in the flower, while Rg4CL2 was expressed mostly in the shoot. Furthermore, considerable transient induction of only Rg4CL1 was observed upon elicitation of Ruta cells, which seems to support a role of Rg4CL1 in coumarin biosynthesis.

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“…Pyrrolizidine alkaloids are synthesized in endodermal and cortical cells immediately adjacent to the phloem in roots of Senecio vernalis (Moll et al 2002), or throughout the cortex in Eupatorium cannabinum roots (Anke et al 2004). The biosynthesis and storage of acridone alkaloids are also associated with endodermis in Ruta graveolens (Junghanns et al 1998).…”

Section: Cellular and Subcellular Localizationmentioning

confidence: 99%

Opium poppy: blueprint for an alkaloid factory

et al. 2007

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Opium poppy (Papaver somniferum) produces a large number of benzylisoquinoline alkaloids, including the narcotic analgesics morphine and codeine, and has emerged as one of the most versatile model systems to study alkaloid metabolism in plants. As summarized in this review, we have taken a holistic strategy-involving biochemical, cellular, molecular genetic, genomic, and metabolomic approaches-to draft a blueprint of the fundamental biological platforms required for an opium poppy cell to function as an alkaloid factory. The capacity to synthesize and store alkaloids requires the cooperation of three phloem cell types-companion cells, sieve elements, and laticifers-in the plant, but also occurs in dedifferentiated cell cultures. We have assembled an opium poppy expressed sequence tag (EST) database based on the attempted sequencing of more than 30,000 cDNAs from elicitor-treated cell culture, stem, and root libraries. Approximately 23,000 of the elicitor-induced cell culture and stem ESTs are represented on a DNA microarray, which has been used to examine changes in transcript profile in cultured cells in response to elicitor treatment, and in plants with different alkaloid profiles. Fourier transform-ion cyclotron resonance mass spectrometry and proton nuclear magnetic resonance mass spectroscopy are being used to detect corresponding differences in metabolite profiles. Several new genes involved in the biosynthesis and regulation of alkaloid pathways in opium poppy have been identified using genomic tools. A biological blueprint for alkaloid production coupled with the emergence of reliable transformation protocols has created an unprecedented opportunity to alter the chemical profile of the world's most valuable medicinal plant.

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Differential regulation and distribution of Acridone Synthase in Ruta graveolens in honour of Professor G. H. Neil Towers 75th birthday

Cited by 32 publications

References 23 publications

Cell Type–Specific Localization of Transcripts Encoding Nine Consecutive Enzymes Involved in Protoberberine Alkaloid Biosynthesis

Cell Type–Specific Localization of Transcripts Encoding Nine Consecutive Enzymes Involved in Protoberberine Alkaloid Biosynthesis

Unusually divergent 4-coumarate:CoA-ligases from Ruta graveolens L.

Opium poppy: blueprint for an alkaloid factory

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