The cystathionine-γ-synthase gene involved in methionine biosynthesis is highly expressed and auxin-repressed during wild strawberry (Fragaria vesca L.) fruit ripening

Marty, Isabelle; Douat, Corinne; Tichit, L.; Jungsup, K.; Leustek, Thomas; Abagnac, G.

doi:10.1007/s001220051396

Cited by 17 publications

(16 citation statements)

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“…Similar morphological aberrations are produced in Arabidopsis by inhibition of CGS expression through antisense RNA (Kim and Leustek, 2000). Both Met and SAM play central roles in plant metabolism.…”

Section: Table III Amino Acid Content In Transgenic Arabidopsis Thatmentioning

confidence: 81%

“…Inhibition of DNA methylation produces defects in apical dominance and flowering (Finnegan et al, 1996;Ronemus et al, 1996), also characteristic of CGS-and SAMS-silenced plants. Finally, several groups have reported that CGS expression is increased in developing fruits (Nam et al, 1999;Hadfield et al, 2000;Marty et al, 2000), and SAMS is highly expressed in developing pea seeds (Gomez-Gomez and Carrasco, 1998), further indicating their likely importance in fruit development.…”

Section: Table III Amino Acid Content In Transgenic Arabidopsis Thatmentioning

confidence: 98%

“…Amino acids also accumulate in Arabidopsis where CGS level is reduced by expression of antisense RNA (Kim and Leustek, 2000). The only major difference between the lines is that SAMS-silenced plants accumulate Met and SMM, whereas CGS-silenced plants do not.…”

Section: Table III Amino Acid Content In Transgenic Arabidopsis Thatmentioning

confidence: 99%

“…In the Arabidopsis mutant mto1, CGS is overexpressed, resulting in overaccumulation of soluble Met (Inaba et al, 1994;Chiba et al, 1999). Finally, antisense-RNA repression of CGS expression results in growth deformities stemming from an inability to synthesize Met (Gakiére et al, 2000;Kim and Leustek, 2000).CGS expression may be regulated in Arabidopsis by an autogenous mechanism, revealed through analysis of the mutant mto1 (Chiba et al, 1999). In wild-type Arabidopsis, Met or a metabolite thereof down-regulates CGS enzyme expression (Fig.…”

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Constitutive Overexpression of Cystathionine γ-Synthase in Arabidopsis Leads to Accumulation of Soluble Methionine andS-Methylmethionine

et al. 2002

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The committing step in Met and S-adenosyl-l-Met (SAM) synthesis is catalyzed by cystathionine ␥-synthase (CGS). Transgenic Arabidopsis plants overexpressing CGS under control of the cauliflower mosaic virus 35S promoter show increased soluble Met and its metabolite S-methyl-Met, but only at specific stages of development. The highest level of Met and S-methyl-Met was observed in seedling tissues and in flowers, siliques, and roots of mature plants where they accumulate 8-to 20-fold above wild type, whereas the level in mature leaves and other tissues is no greater than wild type. CGS-overexpressing seedlings are resistant to ethionine, a toxic Met analog. With these properties the transgenic lines resemble mto1, an Arabidopsis, CGS-mutant inactivated in the autogenous control mechanism for Met-dependent downregulation of CGS expression. However, wild-type CGS was overexpressed in the transgenic plants, indicating that autogenous control can be overcome by increasing the level of CGS mRNA through transcriptional control. Several of the transgenic lines show silencing of CGS resulting in deformed plants with a reduced capacity for reproductive growth. Exogenous feeding of Met to the most severely affected plants partially restores their growth. Similar morphological deformities are observed in plants cosuppressed for SAM synthetase, even though such plants accumulate 250-fold more soluble Met than wild type and they overexpress CGS. The results suggest that the abnormalities associated with CGS and SAM synthetase silencing are due in part to a reduced ability to produce SAM and that SAM may be a regulator of CGS expression.Met is derived from Asp as are the amino acids Lys, Thr, and Ile. The committing step in Met synthesis occurs when the side chain of O-phosphohomoserine (OPH) condenses with the thiol group of Cys to form cystathionine (Fig. 1), an irreversible reaction catalyzed by CGS (EC 4.2.99.9). Cystathionine is cleaved to form homocysteine, which is then methylated with 5-methyltetrahydrofolate to form Met. The major metabolic fates of Met include its incorporation into protein, adenosylation to form SAM, and methylation to form S-methyl Met (SMM) (Fig. 1).CGS competes with TS for OPH, their common substrate. Thus, TS may exert some control over the rate with which OPH is channeled toward Met (Bartlem et al., 2000; Fig. 1). TS is allostrically regulated by SAM (Curien et al., 1998) suggesting that Met synthesis could influence TS activity. Even so, several lines of evidence indicate that CGS controls the rate of Met synthesis. CGS activity decreases when Met is fed to the aquatic angiosperm Lemna paucicostata and increases when Met synthesis is blocked by inhibition of aspartokinase, the first enzyme in the biosynthesis of the Asp family of amino acids (Thompson et al., 1982). In the Arabidopsis mutant mto1, CGS is overexpressed, resulting in overaccumulation of soluble Met (Inaba et al., 1994;Chiba et al., 1999). Finally, antisense-RNA repression of CGS expression results in growth deformities stemming ...

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Section: Table III Amino Acid Content In Transgenic Arabidopsis Thatmentioning

confidence: 81%

Section: Table III Amino Acid Content In Transgenic Arabidopsis Thatmentioning

confidence: 98%

Section: Table III Amino Acid Content In Transgenic Arabidopsis Thatmentioning

confidence: 99%

mentioning

confidence: 99%

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confidence: 99%

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Constitutive Overexpression of Cystathionine γ-Synthase in Arabidopsis Leads to Accumulation of Soluble Methionine andS-Methylmethionine

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Amino Acids

Hoefgen

Hesse

Galili

2004

Handbook of Plant Biotechnology

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Amino acids perform essential functions in both primary and secondary plant metabolism besides their obvious role in protein synthesis. They can be categorised on the basis of their function such as serving to assimilate and transport nitrogen from sources to sinks or serving as precursors for secondary products such as hormones, vitamins, co‐factors and compounds in plant defence. Thus, synthesis of amino acids directly or indirectly controls various aspects of plant growth and development. Recent investigations of genes involved in amino acid biosynthesis reveal that this is a dynamic process controlled by metabolic, environmental and developmental factors including mineral nutrients such as nitrate and sulphate. This chapter intends to provide fundamental knowledge on nitrogen and sulphur metabolism as basis for amino acid biosynthesis and to highlight examples in which combined molecular, biochemical and genetic approaches have helped to define the pathways and uncover regulatory mechanisms of amino acid biosynthesis in plants. These studies have implications for both basic and applied research because amino acid biosynthesis is as well a target for herbicide action as an option to improve the nutritional quality of crops by metabolic engineering and plant breeding.

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Strawberry Biotechnology

Hokanson

Maas

2001

Plant Breeding Reviews

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The cystathionine-γ-synthase gene involved in methionine biosynthesis is highly expressed and auxin-repressed during wild strawberry (Fragaria vesca L.) fruit ripening

Cited by 17 publications

References 26 publications

Constitutive Overexpression of Cystathionine γ-Synthase in Arabidopsis Leads to Accumulation of Soluble Methionine andS-Methylmethionine

Constitutive Overexpression of Cystathionine γ-Synthase in Arabidopsis Leads to Accumulation of Soluble Methionine andS-Methylmethionine

Amino Acids

Strawberry Biotechnology

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