Multicellular living organisms and unmodified parts thereof and – Method of introducing a polynucleotide molecule into or... – The polynucleotide contains a tissue – organ – or cell...
Reexamination Certificate
1998-01-29
2002-04-30
Nelson, Amy J. (Department: 1638)
Multicellular living organisms and unmodified parts thereof and
Method of introducing a polynucleotide molecule into or...
The polynucleotide contains a tissue, organ, or cell...
C435S069100, C435S070100, C435S071100, C435S468000, C435S410000, C435S419000, C435S418000, C800S288000, C800S300000, C800S320000, C800S278000
Reexamination Certificate
active
06380463
ABSTRACT:
The present invention relates to DNA constructs and plants incorporating them. In particular it relates to promoter sequences for the expression of genes which confer herbicide resistance on plants.
Recent advances in plant biotechnology have resulted in the generation of transgenic plants resistant to herbicide application. Herbicide tolerance has been achieved using a range of different transgenic strategies. One well documented example is the use the bacterial xenobiotic detoxifying gene phosphinothricin acetyl transferase (PAT) from
Streptomyces hydroscopicus
. Mutated genes of plant origin, for example the altered target site gene encoding acetolactate synthase (ALS) from Arabidopsis, have been successfully utilised to generate transgenic plants resistant to herbicide application. The PAT and ALS genes have been expressed under the control of strong constitutive promoter.
We propose a system where genes conferring herbicide tolerance would be expressed in an inducible manner dependent upon application of a specific activating chemical. This approach has a number of benefits for the farmer, including the following:
1. Inducible control of herbicide tolerance would alleviate any risk of yield penalties associated with high levels of constitutive expression of herbicide resistance genes. This may be a particular problem as early stages of growth where high levels of transgene product may directly interfere with normal development. Alternatively high levels of expression of herbicide resistance genes may cause a metabolic drain for plant resources.
2. The expression of herbicide resistance genes in an inducible manner allows the herbicide in question to be used to control volunteers if the activating chemical is omitted during treatment.
3. The use of an inducible promoter to drive herbicide resistance genes will reduce the risk of resistant weed species becoming a major problem. If resistance genes were passed onto weed species from related crops, control could still be achieved with the herbicide in the absence of inducing chemical. This would particularly be relevant if the tolerance gene confirmed resistance to a total vegetative control herbicide which would be used (with no inducing chemical) prior to sowing the crop and potentially after the crop has been harvested. For example, it can be envisaged that herbicide resistance in cereals, such as wheat, might outcross into the weed wild oats or that herbicide resistance in oil seed rape or canola could be transferred to wild brassicas thus conferring herbicide resistance to these already troublesome weeds. A further example is that the inducible expression of herbicide resistance in sugar beet will reduce the risk of wild sugar beet becoming a problem.
Several gene regulation systems (gene switches) are known and may be used for conferring inducible herbicide resistance on plants. Many such gene switches are described in the review by Gatz (Current Opinion in Biotechnology (1996) 7, 168-172) and include systems such as the tetracycline repressor gene switch, the Lac repressor system, copper inducible systems such as that based on ACE 1, salicylic acid inducible promoters including the PR-1a system and systems based on sterioid hormones such as the glucocorticoid, progesterone and oestrogen receptor systems. Modifications of the glucocorticoid receptor systems which include the GAL 4 binding domain from yeast and the VP 16 activator are described by Aoyama et al,
The Plant Cell
, (1995) 7, 1773-1785 and it is envisaged that similar systems may based on, for example insect steroid hormones rather than on mammalian steriod hormones. Indeed, a system based on the ecdysone receptor of
Heliothis virescens
has recently been described. Benzene sulphonamide gene switching systems are also known (Hershey et al,
Plant Mol. Biol
., 17, 679-690 (1991) as are systems based on the alcR protein from
Aspergillus nidulans
and glutathione S-transferase promoters.
Several genes which confer herbicide resistance are also known, for example, one herbicide to which resistance genes have been described and which is extremely widely used is N-phosphonomethyl-glycine (glyphosate) and its agriculturally acceptable salts including the isopropylamine, trimethylsulphonium, sodium, potassium and ammonium salts.
In a first aspect of the present invention there is provided a chemically inducible plant gene expression cassette comprising an inducible promoter operatively linked to a target gene which confers resistance to a herbicide.
Any herbicide resistance gene may be used but genes which confer resistance to N-phosphonomethyl-glycine or salts or derivatives thereof are especially preferred.
Several inducible promoters may be used to confer the inducible resistance and these include any of those listed above.
However, a particularly useful gene switch for use in this area is based on the alcR regulatory protein from
Aspergilluis nidulans
which activates genes expression from the alcA promoter in the presence of certain alcohols and ketones. This system is described in our International Patent Publication No. WO93/21334 which is incorporated herein by reference.
The alcA/alcR gene activation system from the fungus
Aspergillus nidulans
is also well characterised. The ethanol utilisation pathway in
A. nidulans
is responsible for the degradation of alcohols and aldehydes. Three genes have been shown to be involved in the ethanol utilisation pathway. Genes alcA and alcR have been shown to lie close together on linkage group VII and aldA maps to linkage group VIII (Pateman J H et al, 1984, Proc. Soc. Lond, B217:243-264; Sealy-Lewis E M and Lockington R A, 1984, Curr. Genet, 8:253-259). Gene alcA encodes ADHI in
A. nidulans
and aldA encodes aldDH, the second enzyme responsible for ethanol utilisation. The expression of both alcA and aldA are induced by ethanol and a number of other inducers (Creaser E H et al, 1984, Biochemical J. 255:449-454) via the transcription activator alcR. The alcR gene and a co-inducer are responsible for the expression of alcA and aldA since a number of mutations and deletions in alcR result in the pleiotropic loss of ADHI and aldDH (Felenbok B et al, 1988, Gene, 73:385-396; Pateman et al, 1984; Sealy-Lewis & Lockington, 1984). The ALCR protein activates expression from alcA by binding to three specific sites in the alcA promoter (Kulmberg P et al, 1992, J. Biol. Chem, 267:21146-21153).
The alcR gene was cloned (Lockington R A et al, 1985, Gene, 33:137-149) and sequenced (Felenbok et al, 1988). The expression of the alcR gene is inducible, autoregulated and subject to glucose repression mediated by the CREA repressor (Bailey C and Arst H N, 1975, Eur. J. Biochem, 51:573-577; Lockington R A et al, 1987, Mol. Microbiology, 1:275-281; Dowzer C E A and Kelly J M, 1989, Curr. Genet, 15:457-459; Dowzer C E A and Kelly J M, 1991, Mol. Cell. Biol, 11:5701-5709). The ALCR regulatory protein contains 6 cysteines near its N terminus coordinated in a zinc binuclear cluster (Kulmberg P et al, 1991, FEBS Letts, 280:11-16). This cluster is related to highly conserved DNA binding domains found in transcription factors of other ascomycetes. Transcription factors GAL4 and LAC9 have been shown to have binuclear complexes which have a cloverleaf type structure containing two Zn(II) atoms (Pan T and Coleman J E, 1990, Biochemistry, 29:3023-3029; Halvorsen Y D C et al, 1990, J. Biol. Chem, 265:13283-13289). The structure of ALCR is similar to this type except for the presence of an asymmetrical loop of 16 residues between Cys-3 and Cys-4. ALCR positively activates expression of itself by binding to two specific sites in its promoter region (Kulmberg P et al, 1992, Molec. Cell. Biol, 12:1932-1939).
The regulation of the three genes, alcR, alcA and aldA, involved in the ethanol utilisation pathway is at the level of transcription (Lockington et al, 1987; Gwynne D et al, 1987, Gene, 51:205-216; Pickett et al, 1987, Gene, 51:217-226).
There are two other alcohol dehydrogenases present in
A. nidulans
. ADHII is present in mycelia grown in non
Hale and Dorr LLP
Nelson Amy J.
Zaghmout O. M. F.
Zeneca Limited
LandOfFree
Inducible herbicide resistance does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Inducible herbicide resistance, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Inducible herbicide resistance will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2903920