# US 7,608,754 B2 · Double fructan beets

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- Number: US 7,608,754 B2
- Document ID: US7608754B2
- Status: Granted
- Kind: B2
- Application number: 10/415,686
- Filed: 2002-06-25
- Published: 2004-04-01
- Granted: 2009-10-27
- Earliest claimed: 2001-06-25
- Assignees: SES Europe N.V./S.A.
- Inventors: Guy Weyens; Jean Lathouwers; Cornelius (Kees) Van Dun
- Web page: https://patentgrep.com/patent/US7608754B2

## CPC

- C12N 15/8246: {Non-starch polysaccharides, e.g. cellulose, fructans, levans}
- C12P 19/18: produced by the action of a glycosyl transferase, e.g. alpha-, beta- or gamma-cyclodextrins
- C12N: MICROORGANISMS OR ENZYMES; COMPOSITIONS THEREOF; PROPAGATING, PRESERVING, OR MAINTAINING MICROORGANISMS; MUTATION OR GENETIC ENGINEERING; CULTURE MEDIA (microbiological testing media C12Q1/00)
- C12P: FERMENTATION OR ENZYME-USING PROCESSES TO SYNTHESISE A DESIRED CHEMICAL COMPOUND OR COMPOSITION OR TO SEPARATE OPTICAL ISOMERS FROM A RACEMIC MIXTURE {(brewing of beer C12C; producing vinegar C12J; producing specific peptides or proteins C07K; producing enzymes C12N9/00; DNA or RNA concerning genetic engineering, vectors, e.g. plasmids, or their isolation, preparation or purification C12N15/00; measuring or testing processes involving enzymes or microorganisms C12Q; measuring or testing processes involving nucleic acid amplification reactions C12Q1/6844; fermentation processes to form a food composition, A21 or A23; compounds in general, see the relevant compound class, e.g. C01, C07)}

## Abstract

The present invention relates to fructan producing plants particularly to methods for the production of fructans having a low degree of polymerization. The invention is also directed to non-fructan producing plants which are transformed or crossed to contain at least two of three genes encoding a fructosyltransferase.

## Claims

### Claim 1

A method for producing fructans having a degree of polymerization (DP) of from DP2 to DP5, comprising the steps of:
(a) selecting two genes of plant origin which encode different fructosyltransferase enzymes, wherein the two different fructosyltransferase enzymes are 1-SST and 6G-FFT or 1-SST and 6-SFT;
(b) operably linking the genes to suitable transcription-initiation and transcription-termination signals to provide an expression construct;
(c) transforming a sugar beet or sugarcane host plant cell with the expression construct;
(d) regenerating a transgenic plant from the transformed plant cell;
(e) cultivating the transgenic plant under conditions enabling the expression of the two fructosyltransferase enzymes during biosynthesis of the fructans; and
(f) isolating the fructans from the transgenic plant, wherein the percentage of DP3 is greater than DP2.

### Claim 2 (depends on 1)

The method of claim 1 wherein the isolated fructan has a DP of 3 or above.

### Claim 3 (depends on 1)

The method of claim 1 wherein the isolated fructan has a DP of 3 or above formed at least in part from isokestose produced by a 1-SST gene.

### Claim 4 (depends on 1)

The method of claim 1 wherein the isolated fructan has a DP of 3 or above and is formed at least in part from fructan synthesis based on a 1-kestose substrate.

### Claim 5

A method for producing seeds of transgenic plants which accumulate fructans having a degree of polymerization (DP) at or above DP3, wherein the percentage of DP3 is greater than DP2, comprising the steps of:
(a) selecting two genes of plant origin which encode different fructosyltransferase enzymes, wherein the two different fructosyltransferase enzymes are 1-SST and 6G-FFT or 1-SST and 6-SFT;
(b) operably linking the genes to suitable transcription-initiation and transcription-termination signals to provide an expression construct;
(c) transforming a sugar beet or sugarcane host plant cell with the expression construct;
(d) regenerating a transgenic plant from the transformed plant cell;
(e) cultivating the transgenic plant under conditions enabling the expression of the two fructosyltransferase enzymes; and
(f) producing seed of transgenic plants which express the two fructosyltransferase enzymes.

### Claim 6

A transgenic plant which accumulates fructans having a degree of polymerization (DP) at or above DP2 comprising: two genes of plant origin which encode different fructosyltransferase enzymes, wherein the two different fructosyltransferase enzymes are 1-SST and 6G-FFT or 1-SST and 6-SFT, operably linked to a suitable transcription-initiation and transcription-termination signal to provide an expression construct which encodes fructosyltransferase enzymes which convert at least one substrate into a fructan having at least a DP2, wherein the transgenic plant is selected from sugar beet or sugarcane and wherein the percentage of DP3 is greater than DP2.

### Claim 7

A transgenic plant comprising at least two different genes of plant origin which encode two different fructosyltransferase enzymes, wherein the two different fructosyltransferase enzymes are 1-SST and 6G-FFT or 1-SST and 6-SFT, operably linked to one or more suitable transcription initiation and transcription termination signals to provide an expression construct, wherein said transgenic plant expresses fructans having a degree of polymerization (DP) ranging from DP2 to DP5, and said transgenic plant is selected from sugar beet or sugarcane, and wherein the percentage of DP3 is greater than DP2.

### Claim 8 (depends on 7)

The transgenic plant according to claim 7 wherein the percentage of DP3 is greater than DP4.