Transgenic potato plants reveal the indispensable role of cystathionine β‐lyase in plant growth and development

Maimann, Stefanie; Wagner, Cornelia; Kreft, Oliver; Zeh, Michaela; Willmitzer, Lothar; Höfgen, Rainer; Hesse, Holger

doi:10.1046/j.1365-313x.2000.00842.x

Cited by 42 publications

(30 citation statements)

References 45 publications

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“…Such an increase has also been noted in transgenic potato plants with down-regulated CbL activity (Maimann et al, 2000). In these plants, cystathionine accumulated in significant amounts.…”

Section: Discussionmentioning

confidence: 58%

Regulation of aspartate-derived amino acid homeostasis in potato plants (Solanum tuberosum L.) by expression of E. coli homoserine kinase

et al. 2007

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Summary. The availability of the carbon backbone O-phosphohomoserine (OPHS) is critical to methionine (met) and threonine (thr) synthesis. OPHS derives from homoserine and is formed by homoserine kinase (HSK). To clarify the function of HSK in cellular metabolism, the E. coli HSK ortholog thrB was expressed in potato plants targeting the EcHSK protein to chloroplasts and to the cytosol. Both approaches resulted in up to 11 times increased total HSK enzyme activity. Transgenic plants exhibited reduced homoserine levels while met and thr did not accumulate significantly. However, the precursor cysteine and upstream intermediates of met such as cystathionine and homocysteine did indicating an accelerated carbon flow towards the end products. Coincidently, plants with elevated cytosolic levels of EcHSK exhibited a reduction in transcript levels of the endogenous HSK, as well as of threonine synthase (TS), cystathionine b-lyase (CbL), and met synthase (MS). In all plants, cystathionine g-synthase (CgS) expression remained relatively unchanged from wild type levels, while S-adenosylmethionine synthetase (SAMS) expression increased. Feeding studies with externally supplied homoserine fostered the synthesis of met and thr but the regulation of synthesis of both amino acids retained the wild type regulation pattern. The results indicate that excess of plastidial localised HSK activity does not influence the de novo synthesis of met and thr. However, expression of HSK in the cytosol resulted in the down-regulation of gene expression of pathway genes probably mediated via OPHS. We integrated these data in a novel working model describing the regulatory mechanism of met and thr homeostasis.

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“…Such an increase has also been noted in transgenic potato plants with down-regulated CbL activity (Maimann et al, 2000). In these plants, cystathionine accumulated in significant amounts.…”

Section: Discussionmentioning

confidence: 58%

Regulation of aspartate-derived amino acid homeostasis in potato plants (Solanum tuberosum L.) by expression of E. coli homoserine kinase

et al. 2007

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“…The amplification product was sequenced and 32 P-labeled by random priming. Hybridization and washing conditions were performed as described by Maimann et al (2000).…”

Section: Northern Hybridizationmentioning

confidence: 99%

Involvement of Ethylene in Stress-Induced Expression of the TLC1.1 Retrotransposon from Lycopersicon chilense Dun.

et al. 2005

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The TLC1 family is one of the four families of long terminal repeat (LTR) retrotransposons identified in the genome of Lycopersicon chilense. Here, we show that this family of retroelements is transcriptionally active and its expression is induced in response to diverse stress conditions such as wounding, protoplast preparation, and high salt concentrations. Several stressassociated signaling molecules, including ethylene, methyl jasmonate, salicylic acid, and 2,4-dichlorophenoxyacetic acid, are capable of inducing TLC1 family expression in vivo. A representative of this family, named TLC1.1, was isolated from a genomic library from L. chilense. Transient expression assays in leaf protoplasts and stably transformed tobacco (Nicotiana tabacum) plants demonstrate that the U3 domain of the 5#-LTR region of this element can drive stress-induced transcriptional activation of the b-glucuronidase reporter gene. Two 57-bp tandem repeated sequences are found in this region, including an 8-bp motif, ATTTCAAA, previously identified as an ethylene-responsive element box in the promoter region of ethyleneinduced genes. Expression analysis of wild-type LTR and single and double ethylene-responsive element box mutants fused to the b-glucuronidase gene shows that these elements are required for ethylene-responsive gene expression in protoplasts and transgenic plants. We suggest that ethylene-dependent signaling is the main signaling pathway involved in the regulation of the expression of the TLC1.1 element from L. chilense.

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“…1), a reduction in CBL level through antisense inhibition in potato (Maimann et al, 2000) resulted in increased levels of the upstream metabolites cysteine, cystathionine, and homoserine, while threonine remained constant and methionine was only slightly reduced. Whether total free amino acids were increased was not determined.…”

Section: Increasing Methionine Levelsmentioning

confidence: 99%

Metabolic Engineering of Amino Acids and Storage Proteins in Plants

Galili

Höfgen

2002

Metabolic Engineering

169

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Transgenic potato plants reveal the indispensable role of cystathionine β‐lyase in plant growth and development

Cited by 42 publications

References 45 publications

Regulation of aspartate-derived amino acid homeostasis in potato plants (Solanum tuberosum L.) by expression of E. coli homoserine kinase

Regulation of aspartate-derived amino acid homeostasis in potato plants (Solanum tuberosum L.) by expression of E. coli homoserine kinase

Involvement of Ethylene in Stress-Induced Expression of the TLC1.1 Retrotransposon from Lycopersicon chilense Dun.

Metabolic Engineering of Amino Acids and Storage Proteins in Plants

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