Altered linolenic and linoleic acid content in plants

1. A genetically transformed plant which has a reduced linolenic acid content relative to non-transformed plants of the same species, comprising a recombinant, double-stranded DNA molecule comprising:

(i) a promoter that functions in plant cells to cause the production of an RNA sequence, said promoter operably linked to;

(ii) a DNA sequence that causes the production of an RNA sequence that is in antisense orientation to at least 959 bp of a gene comprising SEQ ID NO:1, or SEQ ID NO:11; and

(iii) a 3′ non-translated region that functions in plant cells to promote polyadenylation to the 3′ end of said RNA sequence.

2. The plant of claim 1 in which the structural coding sequence of (ii) is taken from SEQ. ID NO:1.

3. The plant of claim 1 in which the structural coding sequence of (ii) is taken from SEQ. ID NO:11.

4. A genetically transformed canola plant which has a linolenic acid content of less than about 3%, said plant comprising a recombinant, double-stranded DNA molecule comprising:

(i) a promoter that functions in plant cells to cause the production of an RNA sequence, said promoter operably linked to;

(ii) a DNA sequence that causes the production of an RNA sequence that is in antisense orientation to at least 959 bp of a gene comprising SEQ ID NO:1, or SEQ ID NO:11; and

(iii) a 3′ non-translated region that functions in plant cells to promote polyadenylation to the 3′ end of said RNA sequence.

5. A genetically transformed canola plant which has an increased oleic acid content relative to non-transformed plants of the same species, comprising a recombinant, double-stranded DNA molecule comprising:

(i) a promoter that functions in plant cells to cause the production of an RNA sequence, said promoter operably linked to;

(ii) a DNA sequence that causes the production of an RNA sequence that is in antisense orientation to at least 959 bp of a gene comprising SEQ ID NO:1, or SEQ ID NO:11; and

(iii) a 3′ non-translated region that functions in plant cells to promote polyadenylation to the 3′ end of said RNA sequence.

6. A method of producing a genetically transformed plant which has a reduced linolenic acid content relative to non-transformed plants of the same species, comprising:

(a) inserting into the genome of a plant cell a recombinant, double-stranded DNA molecule comprising:

(i) a promoter that functions in plant cells to cause the production of an RNA sequence, said promoter operably linked to;

(ii) a DNA sequence that causes the production of an RNA sequence that is in antisense orientation to at least 959 bp of a gene comprising SEQ ID NO:1, or SEQ ID NO:11; and

(iii) a 3′ non-translated region that functions in plant cells to promote polyadenylation to the 3′ end of said RNA sequence

(b) obtaining transformed plant cells; and

(c) regenerating from the transformed plant cells genetically transformed plants which have a reduced linolenic acid content.

7. The method of claim 6 in which the structural coding sequence of (ii) is taken from SEQ. ID NO:1.

8. The method of claim 6 in which the structural coding sequence of (ii) is taken from SEQ. ID NO:11.

9. A method of producing a genetically transformed canola plant which has an increased oleic acid content relative to non-transformed plants of the same species, comprising:

(a) inserting into the genome of a plant cell a recombinant, double-stranded DNA molecule comprising:

(i) a promoter that functions in plant cells to cause the production of an RNA sequence, said promoter operably linked to;

(ii) a DNA sequence that causes the production of an RNA sequence that is in antisense orientation to at least 959 bp of a gene comprising SEQ ID NO:1, or SEQ ID NO:11; and

(iii) a 3′ non-translated region that functions in plant cells to promote polyadenylation to the 3′ end of said RNA sequence

(b) obtaining transformed plant cells; and

(c) regenerating from the transformed plant cells genetically transformed plants which have an increased oleic acid content.

10. A recombinant, double-stranded DNA molecule comprising in sequence:

(i) a promoter that functions in plant cells to cause the production of an RNA sequence, said promoter operably linked to;

(ii) a DNA sequence that causes the production of an RNA sequence that is in antisense orientation to at least 959 bp of a gene comprising SEQ ID NO:1, or SEQ ID NO:11; and

(iii) a 3′ non-translated region that functions in plant cells to promote polyadenylation to the 3′ end of said RNA sequence.

11. A plant cell comprising a recombinant, double-stranded DNA molecule comprising in sequence:

(i) a promoter that functions in plant cells to cause the production of an RNA sequence, said promoter operably linked to;

(ii) a DNA sequence that causes the production of an RNA sequence that is in antisense orientation to at least 959 bp of a gene comprising SEQ ID NO:1, or SEQ ID NO:11; and

(iii) a 3′ non-translated region that functions in plant cells to promote polyadenylation to the 3′ end of said RNA sequence.

12. A genetically transformed canola plant which has a reduced linolenic acid content and an increased oleic acid content relative to non-transformed plants of the same species, comprising a recombinant, double-stranded DNA molecule comprising:

(i) a promoter that functions in plant cells to cause the production of an RNA sequence, said promoter operably linked to;

(ii) a DNA sequence that causes the production of an RNA sequence that is in antisense orientation to at least 959 bp of a gene comprising SEQ ID NO:1, or SEQ ID NO:11; and

(iii) a 3′ non-translated region that functions in plant cells to promote polyadenylation to the 3′ end of said RNA sequence.

13. A method of producing a genetically transformed canola plant which has a reduced linolenic acid content and an increased oleic acid content relative to non-transformed plants of the same species, comprising:

(a) inserting into the genome of a plant cell a recombinant, double-stranded DNA molecule comprising:

(i) a promoter that functions in plant cells to cause the production of an RNA sequence, said promoter operably linked to;

(ii) a DNA sequence that causes the production of an RNA sequence that is in antisense orientation to at least 959 bp of a gene comprising SEQ ID NO:1, or SEQ ID NO:11; and

(iii) a 3′ non-translated region that functions in plant cells to promote polyadenylation to the 3′ end of said RNA sequence

(b) obtaining transformed plant cells; and

(c) regenerating from the transformed plant cells genetically transformed plants which have a reduced linolenic acid content.

14. The plant of claim 1 , further defined as sunflower, safflower, cotton, corn, wheat, rice, peanut, canola/oilseed rape, barley, sorghum , soybean, flax, tomato, almond, cashew or walnut.

15. An isolated nucleic acid sequence encoding a delta-15 fatty acid desaturase enzyme, which catalyzes a reaction at C15–C16 of linoleic acid comprising SEQ ID NOS: 1 or 11.

16. The isolated nucleic acid sequence of claim 15 which encodes a protein comprising any one of the amino acid sequences set forth in SEQ ID NOS: 2 or 12.

17. A chimeric gene capable of causing altered levels of linolenic acid in a transformed plant cell, the gene comprising a nucleic acid sequence of claim 15 or claim 16 , the fragment operably linked to suitable regulatory sequences.

18. Plants containing the chimeric gene of claim 17 .

19. A method of producing seed oil containing altered levels of linolenic (18:3) acid comprising:

(a) transforming a plant cell of an oil-producing species with a chimeric gene of claim 17 ;

(b) growing fertile plants from the transformed plant cells of step (a);

(c) screening progeny seeds from the fertile plants of step (b) for the desired levels of linolenic (18:3) acid; and

(d) processing the progeny seed of step (c) to obtain seed oil containing altered levels of linolenic (18:3) acid.

20. The method of claim 19 wherein said plant cell of an oil-producing species is selected from the group consisting of Arabidopsis thaliana , soybean, oilseed Brassica napus , sunflower, cotton, peanut, and corn.