Amino acid auxotrophs from protoplast cultures of Nicotiana plumbaginifolia, Viviani

Negrutiu, Ioan; Brouwer, Dirk De; Dirks, R.; Jacobs, M.

doi:10.1007/bf00330276

Cited by 61 publications

(22 citation statements)

References 21 publications

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“…Isolated examples of auxotrophs have been reported in maize (Zea mays; Racchi et al, 1978), Arabidopsis (Last and Fink, 1988;Niyogi et al, 1993;Noutoshi et al, 2005), Nicotiana (Negrutiu et al, 1985(Negrutiu et al, , 1992, and Physcomitrella (Schween et al, 2005) and in cell cultures from a variety of plants (Blonstein, 1986). A comprehensive collection of amino acid auxotrophs in a model angiosperm, however, remains to be established.…”

Section: Expected Phenotypes Of Amino Acid Auxotrophsmentioning

confidence: 99%

“…One is a haploid cell line of Nicotiana plumbaginifolia with a missense mutation affecting the aminotransferase (HISN6) that catalyzes a late step in the pathway (Negrutiu et al, 1985;El Malki and Jacobs, 2001). A second example is an embryodefective (emb) mutant of Arabidopsis (emb2196) identified through a forward genetic screen of T-DNA insertion mutants (Tzafrir et al, 2004).…”

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Genetic Dissection of Histidine Biosynthesis in Arabidopsis

et al. 2007

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Section: Expected Phenotypes Of Amino Acid Auxotrophsmentioning

confidence: 99%

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confidence: 99%

Genetic Dissection of Histidine Biosynthesis in Arabidopsis

et al. 2007

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“…Further propagation and replication of plantlets was performed on claforan-containing medium (Murashige and Skoog medium with 2% [w/v] Suc). During a11 tissue culture procedures, as well as for later propagation, the medium was enriched with 0.5 g/L casein hydrolysate (casamino acids, Merck, Darmstadt, Germany) to complement for the expected ALS antisense-mediated deficiency in amino acid biosynthesis (Negrutiu et al, 1985).…”

Section: Plant Transformationmentioning

confidence: 99%

Repression of Acetolactate Synthase Activity through Antisense Inhibition (Molecular and Biochemical Analysis of Transgenic Potato (Solanum tuberosum L. cv Desiree) Plants)

Höfgen¹,

Laber²,

Schüttke³

et al. 1995

Plant Physiol.

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Acetolactate synthase (ALS), the first enzyme in the biosynthetic pathway of leucine, valine, and isoleucine, is the biochemical target of different herbicides. To investigate the effects of repression of ALS activity through antisense gene expression we cloned an ALS gene from potato (Solanum fuberosum L. cv Désirée), constructed a chimeric antisense gene under control of the cauliflower mosaic virus 35s promoter, and created transgenic potato plants through Agrobacterium fumefaciens-mediated gene transfer. Two regenerants revealed severe growth retardation and strong phenotypical effects resembling those caused by ALS-inhibiting herbicides. Antisense gene expression decreased the steady-state leve1 of ALS mRNA in these plants and induced a corresponding decrease in ALS activity of up to 85%. This reduction was sufficient to generate plants almost inviable without amino acid supplementation. In both ALS antisense and herbicide-treated plants, we could exclude accumulation of 2-oxobutyrate and/or 2-aminobutyrate as the reason for the observed deleterious effects, but we detected elevated levels of free amino acids and imbalances in their relative proportions. Thus, antisense inhibition of ALS generated an in vivo model of herbicide action. Furthermore, expression of antisense RNA to the enzyme of interest provides a general method for validation of potential herbicide targets.

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“…This is an attractive approach to identification of Zt/Dt because the extent of labeling will be high and because in vivo labeling avoids the complications of chemical extraction and reconstitution of membranes. Unfortunately, there are few reports of plant amino acid auxotrophs (29). Instead, we have used cyanobacterial strains in which either quinones or tyrosine can be specifically labeled in vivo.…”

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confidence: 99%

Tyrosine radicals are involved in the photosynthetic oxygen-evolving system.

Barry

Babcock

1987

Proc. Natl. Acad. Sci. U.S.A.

414

312

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In addition to the reaction-center chlorophyll, at least two other organic cofactors are involved in the photosynthetic oxygen-evolution process. One of these cofac.tors, called "Z," transfers electrons from the site of water oxidation to the reaction center of photosystem II. The other species, "D," has an uncertain function but gives rise to the stable EPR signal known as signal II. ZV and D+ have identical EPR spectra and are generally assumed to arise from species with the same chemical structure. Results from a variety of experiments have suggested that Z and D are plastoquinones or plastoquinone derivatives. In general, however, the evidence to support this assignment is indirect. To address this situation, we have developed more direct methods to assign the structure of the ZV/Dt radicals. By selective in vivo deuteration of the methyl groups of plastoquinone in cyanobacteria, we show that hyperfine couplings from the methyl protons cannot be responsible for the partially resolved structure seen in the Dt EPR spectrum. That is, we verify by extraction and mass spectrometry that quinones are labeled in algae fed deuterated methionine, but no change is observed in the line shape of signal II.Considering the spectral properties ofthe Dt radical, a tyrosine origin is a reasonable alternative. In a second series of experiments, we have found that deuteration of tyrosine does indeed narrow the Dt signal. Extraction and mass spectral analysis of the quinones in these cultures show that they are not labeled by tyrosine. These results eliminate a plastoquinone origin for Dt; we conclude instead that Dt, and most likely Zt, are tyrosine radicals.In plant and algal photosynthesis, photosystem II (PSII) catalyzes the light-induced oxidation of water and reduction of plastoquinone. The smallest purified unit that is capable of carrying out this reaction consists of seven polypeptides and contains chlorophyll, plastoquinone, manganese, and several other bound cofactors (for review, see refs. 1 and 2). Water oxidation occurs at a site that contains a cluster of four Mn atoms. This center is interfaced to the photochemically active PSII reaction-center chlorophyll, P680, by at least one intermediate electron carrier, which is usually designated The oxidized form of this cofactor, Zt, has a light-induced EPR signal that identifies it as an organic radical (3-6). A variety of kinetic data indicates that Z reduces P680+ directly and that the resulting Zt species is in turn reduced by the manganese ensemble (refs. 1 and 2, but see refs. 7 and 8). In addition to the EPR signal from Z+, PSII preparations also show a stable EPR signal (signal II) with the same lineshape as Zt (9). The radical giving rise to this spectrum is now usually referred to as "D+". Recent data reported by Styring and Rutherford suggest that D may be involved in maintaining the integrity of the manganese complex (10).Because the Zt and Dt EPR spectra are identical, it is generally assumed that Z and D are species that have the same chemical str...

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Amino acid auxotrophs from protoplast cultures of Nicotiana plumbaginifolia, Viviani

Cited by 61 publications

References 21 publications

Genetic Dissection of Histidine Biosynthesis in Arabidopsis

Genetic Dissection of Histidine Biosynthesis in Arabidopsis

Repression of Acetolactate Synthase Activity through Antisense Inhibition (Molecular and Biochemical Analysis of Transgenic Potato (Solanum tuberosum L. cv Desiree) Plants)

Tyrosine radicals are involved in the photosynthetic oxygen-evolving system.

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