Fatty acid desaturases and mutant sequences thereof

• US 6,967,243 B2
• Filed: 01/29/2001
• Issued: 11/22/2005
• Est. Priority Date: 12/14/1995
• Status: Expired due to Fees

• Current Assignee: Cargill, Inc. (Agricultural Services Division)
• Original Assignee: Cargill, Inc. (Agricultural Services Division)
• Inventors: Debonte, Lorin R., Miao, Guo-Hua, Fan, Zhegong
• Primary Examiner(s): McElwain, Elizabeth F.
• Application Number:
  US09/771,904
• Publication Number:
  US 20030131379A1
• Time in Patent Office: 1,758 Days
• Field of Search: 536/23.2, 536/23.6, 536/23.1
• US Class Current: 536/23.2
• CPC Class Codes: C07C 53/126 Acids containing more than four carbon atoms
• CPC Class Codes: C07C 57/02 with only carbon-to-carbon double bonds as unsaturation
• CPC Class Codes: C07C 57/03 Monocarboxylic acids
• CPC Class Codes: C12N 15/8247 involving modified lipid metabolism, e.g. seed oil composition
• CPC Class Codes: C12N 9/0083 Miscellaneous (1.14.99)

Abstract

Seeds, plants and oils are provided having high oleic acid; low linoleic acid; and low linoleic acid plus linolenic acid; and advantageous functional or nutritional properties. Plants are disclosed that contain a mutation in a delta-12 or delta-15 fatty acid desaturase gene. Preferred plants are rapeseed and sunflower plants. Plants carrying such mutant genes have altered fatty acid composition in seeds. In one embodiment, a plant contains a mutation in a region having the conserved motif His-Xaa-Xaa-Xaa-His, found in delta-12 and delta-15 fatty acid desaturases. A preferred motif has the sequence His-Glu-Cys-Gly-His. A preferred mutation in this motif has the amino acid sequence His-Lys-Cys-Gly-His. Nucleic acid fragments are disclosed that comprise a mutant delta-12 or delta-15 fatty acid desaturase gene sequence.

Claims

1. An isolated nucleic acid comprising a full length delta-12 fatty acid desaturase coding sequence having at least one mutation in a region of said sequence encoding a His-Xaa-Xaa-Xaa-His amino acid motif, wherein said at least one mutation renders the product of said desaturase gene non-functional and wherein said sequence includes said at least one mutation.

2. The nucleic acid of claim 1, wherein said at least one mutation comprises a mutation in a region of said sequence encoding a His-Glu-Cys-Gly-His (SEQ ID NO:

60) amino acid motif.

3. The nucleic acid fragment of claim 2, wherein said at least one mutation in said sequence introduces a non-conservative amino acid substitution in said motif.

4. The nucleic acid of claim 1, wherein said at least one mutation in said sequence introduces a deletion of one or more amino acids in said motif.

5. The nucleic acid of claim 4, wherein said at least one mutation in said sequence introduces a deletion of one amino acid in said motif.

6. The nucleic acid of claim 1 , wherein said at least one mutation in said sequence introduces an insertion of one or more amino acids in said motif.

7. The nucleic acid of claim 6, wherein said at least one mutation said sequence introduces an insertion of one amino acids in said motif.

8. The nucleic acid of claim 3, wherein said at least one mutation in said motif comprises a substitution of a codon encoding Lys for the codon encoding Glu.

9. The nucleic acid of claim 8, wherein said coding sequence encodes a polypeptide having the amino acid sequence of SEQ ID NO:

12.

10. The nucleic acid of claim 9, wherein said sequence is SEQ ID NO:

11.

11. The nucleic acid of claim 3, wherein said sequence encodes a microsomal gene product.