References of "Jacon, Géraldine"
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See detailTransformed Plant Expressing a Mutansucrase and Synthesizing a Modified Starch
Jacon, Géraldine ULg; Frohberg, Claus; Vincken, Jean-Paul et al

Patent (2009)

The present invention relates to plant cells and plants, which are genetically modified, wherein the genetic modification leads to the expression in plastids of such plant cells and plants of an enzyme ... [more ▼]

The present invention relates to plant cells and plants, which are genetically modified, wherein the genetic modification leads to the expression in plastids of such plant cells and plants of an enzyme having the activity of a mutansucrase. Furthermore, the present invention relates to means and methods for the manufacture of such plant cells and plants. Plant cells and plants of this type synthesise a modified starch. The present invention therefore also relates to the starch synthesised by the plant cells and plants according to the invention as well as to methods for the manufacture of the starch and to the manufacture of starch derivatives of this modified starch. [less ▲]

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See detailTransformed Plant Expressing a Dextransucrase and Synthesizing a Modified Starch
Jacon, Géraldine ULg; Frohberg, Claus; Vincken, Jean-Paul et al

Patent (2009)

The present invention relates to plant cells and plants, which are genetically modified, wherein the genetic modification leads to the expression in plastids of such plant cells and plants of an enzyme ... [more ▼]

The present invention relates to plant cells and plants, which are genetically modified, wherein the genetic modification leads to the expression in plastids of such plant cells and plants of an enzyme having the activity of a dextransucrase. Furthermore, the present invention relates to means and methods for the manufacture of such plant cells and plants. Plant cells and plants of this type synthesis a modified starch. The present invention therefore also relates to the starch synthesized by the plant cells and plants according to the invention as well as to methods for the manufacture of the starch and to the manufacture of starch derivatives of this modified starch. [less ▲]

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See detailExpression of alternansucrase in potato plants
Jacon, Géraldine ULg; Vincken, Jean-Paul; Suurs, Luc et al

in Biotechnology Letters (2007), 29

Alternan, which consists of alternating alpha(1 - 3)/alpha (1 - 6)-linked glucosyl residues, was produced in potato tubers by expressing a mature alternansucrase (Asr) gene from Leuconostoc mesenteroides ... [more ▼]

Alternan, which consists of alternating alpha(1 - 3)/alpha (1 - 6)-linked glucosyl residues, was produced in potato tubers by expressing a mature alternansucrase (Asr) gene from Leuconostoc mesenteroides NRRL B-1355 in potato. Detection of alternan was performed by enzyme-linked immunosorbent assay in tuber juices, revealing a concentration between 0.3 and 1.2 mg g–1 fresh wt. The Asr transcript levels correlated well with alternan accumulation in tuber juices. It appeared that the expression of sucrose-regulated starch- synthesizing genes (ADP-glucose pyrophosphorylase subunit S and granule-bound starch synthase I) was down-regulated. Despite this, the physico- chemical properties of the transgenic starches were unaltered. These results are compared to those obtained with other transgenic potato plants producing mutan [alpha (1 - 3)-linked glucosyl residues and dextran [alpha (1 - 6)-linked glucosyl residues]. [less ▲]

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See detailBreeding for Improved and Novel Starch Characteristics in Potato
Jacon, Géraldine ULg

in Biotechnology and Sustainable Agriculture 2006 and Beyond (2007)

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See detailFusion proteins comprising the catalytic domain of mutansucrase and a starch-binding domain can alter the morphology of amylose-free potato starch granules during biosynthesis
Jacon, Géraldine ULg

in Transgenic Research (2007), 16

It has been shown previously that mutan can be co-synthesized with starch when a truncated mutansucrase (GtfICAT) is directed to potato tuber amyloplasts. The mutan seemed to adhere to the isolated starch ... [more ▼]

It has been shown previously that mutan can be co-synthesized with starch when a truncated mutansucrase (GtfICAT) is directed to potato tuber amyloplasts. The mutan seemed to adhere to the isolated starch granules, but it was not incorporated in the starch granules. In this study, GtfICAT was fused to the N- or C-terminus of a starch-binding domain (SBD). These constructs were introduced into two genetically different potato backgrounds (cv. Kardal and amf), in order to bring GtfICAT in more intimate contact with growing starch granules, and to facilitate the incorporation of mutan polymers in starch. Fusion proteins of the appropriate size were evidenced in starch granules, particularly in the amf back- ground. The starches from the various GtfICAT/ SBD transformants seemed to contain less mutan than those from transformants with GtfICAT alone, suggesting that the appended SBD might inhibit the activity of GtfICAT in the engineered fusion proteins. Scanning electron microscopy showed that expression of SBD-GtfICAT resulted in alterations of granule morphology in both genetic backgrounds. Surprisingly, the amf starches con- taining SBD-GtfICAT had a spongeous appearance, i.e., the granule surface contained many small holes and grooves, suggesting that this fusion protein can interfere with the lateral interactions of amylopectin sidechains. No differences in phys- ico-chemical properties of the transgenic starches were observed. Our results show that expression of granule-bound and ‘‘soluble’’ GtfICAT can affect starch biosynthesis differently. [less ▲]

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See detailMutan produced in potato amyloplasts adheres to starch granules
Jacon, Géraldine ULg

in Plant Biotechnology Journal (2005), 3

Production of water-insoluble mutan polymers in Kardal potato tubers was investigated after expression of a full-length (Gtf I) and a truncated mutansucrase gene referred to as GtfICAT (Gtf I without ... [more ▼]

Production of water-insoluble mutan polymers in Kardal potato tubers was investigated after expression of a full-length (Gtf I) and a truncated mutansucrase gene referred to as GtfICAT (Gtf I without glucan-binding domain) from Streptococcus downei. Subsequent effects on starch biosynthesis at the molecular and biochemical levels were studied. Expression of the GtfICAT gene resulted in the adhesion of mutan material on starch granules, which stained red with erythrosine, and which was hydrolysed by exo-mutanase. In addition, GtfICAT-expressing plants exhibited a severely altered tuber phenotype and starch granule morphology in comparison to those expressing the full-length Gtf I gene. In spite of that, no structural changes at the starch level were observed. Expression levels of the sucrose- regulated, AGPase and GBSSI genes were down-regulated in only the GTFICAT transformants, showing that GtfICAT expression interfered with the starch biosynthetic pathway. In accordance with the down-regulated AGPase gene, a lower starch content was observed in the GTFICAT transformants. Finally, the rheological properties of the GTFICAT starches were modified; they showed a higher retrogradation during cooling of the starch paste. [less ▲]

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See detailTowards a more versatile alpha-glucan biosynthesis in plants
Jacon, Géraldine ULg

in Journal of Plant Physiology (2003)

During the last 10 years, the increased need for starches with novel properties has occupied the research community, and many efforts were concentrated on unraveling the starch bio- synthesis pathways ... [more ▼]

During the last 10 years, the increased need for starches with novel properties has occupied the research community, and many efforts were concentrated on unraveling the starch bio- synthesis pathways. The knowledge generated in these investigations was subsequently used to produce tailor-made starches in higher plants using recombinant DNA technology. Examples of starches with new functionalities are those with a modified degree of branching (Schwall et al. 2000, Shewma- ker et al. 1994, Kortstee et al. 1996) and the amylose-free starch (Visser et al. 1991a, Kuipers et al.1994), some of which hold potential for applications in the paper-, textile-, plastics-, food and pharmaceutical industry. The accumulation of more starch has also been an objective, but this will not be dis- cussed further here, (see: Slattery et al. 2000). In our laboratory, we have embarked on two generic tech- nologies with a very wide range of applicability: (i) introduction of new linkages types and structural elements using glu- cansucrases, and (ii) engineering granule-boundness by using microbial starch-binding domains (SBDs). It is expected that these technologies will contribute substantially to the biosynthesis of more versatile α-glucans in the near future, leading to starches with altered functionalities that cannot be obtained by conventional breeding. In this study recent developments in starch modification using heterologous expression of microbial genes will be reviewed, with emphasis on the potato plant. [less ▲]

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