Nova Patents
CA2581440C

Gene silencing

Abstract

The present invention relates to unique strategies and constructs for producing a nucleic acid product that downregulates or prevents expression of a desired target polynucleotide.

CA2581440C, drawing sheet 1
Sheet 1 of 20

Term

Term ended

Expired 23 September 2025, 1 year ago.

  1. Priority
  2. Filed
  3. Granted
  4. Expired
  5. Today

2 claims: 2 independent, 0 dependent

  1. 1
    CA 02581440 2016-08-23 WHAT IS CLAIMED IS:1. A construct comprising an expression cassette which comprises: (i) a first promoter operably linked to a first polynucleotide;and (ii) a second promoter operably linked to a second polynucleotide, wherein: (a) neither the first nor the second polynucleotide is operably linked to a terminator;(b) the second polynucleotide and the first polynucleotide are fully identical in sequence over at least 23 contiguous nucleotides, wherein the second polynucleotide is positioned within the cassette in a different orientation to the first polynucleotide;(c) the direction of transcription initiated from the first promoter is toward the second promoter and the direction of transcription initiated from the second promoter is toward the first promoter;and (d) the first polynucleotide shares sequence identity with a target gene or a sequence associated with the target gene, for at least 23 contiguous nucleotides. 2. The construct of claim 1, wherein neither the first nor the second polynucleotide is operably finked to: (i) a nos gene terminator;(ii) the 3' untranslated sequence of T-DNA gene 7;(iii) the 3' untranslated sequences of the major inclusion body protein gene of cauliflower mosaic virus;(iv) the 3' untranslated sequences of the pea ribulose 1,5-bisphosphate carboxylase small subunit;(v) the 3' untranslated sequences of the potato ubiquitin-3 gene;(vi) the 3' untranslated sequences of the potato proteinase inhibitor 11 gene;(vii) the 3' untranslated sequences of opine genes;or (viii) the 3' untranslated sequences of endogenous genes. 3. The construct of claim 1 or 2, wherein the target gene or the sequence associated with the target gene is at least one of a regulatory element that is associated with the target gene, an exon of the target gene, an intron of the target gene, the 5'-untranslated region of the target gene, or the 3'-untranslated region of the target gene. CA 02581440 2016-08-23 4. The construct of any one of claims 1 to 3, wherein the first and second promoters are functional in a plant and wherein the expression cassette is located between transfer-DNA border sequences of a plasmid that is suitable for bacterium-mediated plant transformation, wherein the bacterium is a strain of Agrobacterium. Rhizobium, or Phyllobaclerium. 5. The construct of any one of claims 1 to 4, further comprising a spacer polynucleotide positioned between the first and second polynucleotides, wherein the spacer polynucleotide is 2, 3,4,5,6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20,21,22, 23,24,25,26, 27, 28, 29, 30. 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44. 45, 46, 47, 48, 49, 50, 60, 70, 80, 90. 100, 110, 120, 130, 140, 150, 160, 170, 180. 190, 200, 300, 400, 500, or more than 500 nucleotides long. 6. The construct of any one of claims 1 to 5, wherein the target gene is: a caffeie aeid/5hydroxyferulic acid 3/5-O-methyltransferase (COMT) gene involved in lignin biosynthesis;a caffeoyl CoA 3-O-methyltransferase (CCOMT) gene involved in lignin biosynthesis;any other gene involved in lignin biosynthesis;an R1 gene involved in starch phosphorylation;a phosphorylase gene involved in starch phosphorylation;a polyphenol oxidase (PPO) gene involved in oxidation of polyphenols;a polygalacturonase gene involved in pectin degradation;a gene involved in the production of allergens;or a gene involved in fatty acid biosynthesis. 7. The construct of claim 6, wherein the target gene is fatty acid desaturase (Fad2). 8. The construct of any one of claims 1 to 7, wherein the first promoter is a constitutive promoter, a near-constitutive promoter, a tissue-specific promoter, or an inducible promoter, and wherein the second promoter is a constitutive promoter, a near-constitutive promoter, a tissuespecific promoter, or an inducible promoter. 9. A transformation plasmid comprising an expression cassette, which comprises in the 5' to 3' orientation (1) a first promoter that is operably linked to (2) a first desired polynucleotide that shares sequence identity with a target gene or a sequence associated with the target gene for at least 23 contiguous nucleotides, which abuts (3) at least one optional spacer polynucleotide, where the 3'-end of one of the spacer polynucleotides abuts (4) a second desired polynucleotide, which is operably linked to (5) a second promoter, wherein neither desired polynucleotide in the expression cassette is operably linked to a transcription terminator, and wherein the second CA 02581440 2016-08-23 polynucleotide and the first polynucleotide are fully identical in sequence over at least 23 contiguous nucleotides, wherein the second polynucleotide is positioned within the cassette in a different orientation to the first polynucleotide, and wherein the direction of transcription initiated from the first promoter is toward the second promoter and the direction of transcription initiated from the second promoter is toward the first promoter. 10. The transformation plasmid of claim 9, wherein (a) at least part of the first desired polynucleotide is in the antisense orientation;or (b) at least part of the first desired polynucleotide is in the sense orientation;or (c) at least part of the first desired polynucleotide of (a) or (b) is a promoter sequence or shares sequence identity with a promoter sequence. 1 1. The transformation plasmid of claim 10, wherein the sequence of (c) shares sequence identity with a promoter that is associated with an endogenous gene, said promoter being: (1) a starch-associated Rl gene promoter, (2) a polyphenol oxidase gene promoter, (3) a fatty acid desaturase 12 gene promoter, (4) a microsomal omega-6 fatty acid desaturase gene promoter, (5) a cotton stearoyl-acyl-carrier protein delta 9-desaturase gene promoter, (6) an oleoylphosphatidylcholine omega 6-desaturase gene promoter, (7) a Medicago truncatula caffeic acid/5-hydroxyferulic acid 3/5-O-methyltransferase (COMT) gene promoter, (8) a Medicago sativa (alfalfa) caffeic acid/5-hydroxyferulic acid 3/5-O-methyltransferase (COMT) gene promoter, (9) a Medicago trunccitula caffeoyl CoA 3-O-methyltransferase (CCOM'l) gene promoter, (10) a Medicago sativa (alfalfa) caffeoyl CoA 3-O-methyltransferase (CCOMT) gene promoter, (11) a Zea mays (maize) COMT gene promoter, (12) a major apple allergen Mal d 1 gene promoter, (13) a major peanut allergen Ara h 2 gene promoter, (14) a major soybean allergen Gly m Bd 30 K gene promoter, (15) a polygalacturonase gene promoter, or (16) any other endogenous promoter. 12. The transformation plasmid of claim 10, wherein (1) (i) at least one of the first and second promoters is a granule-bound starch synthase (GBSS) promoter and (ii) the first desired polynucleotide is a sequence that shares sequence identity with at least a part of a promoter associated with a polyphenol oxidase gene;(2) both the first and second promoters are GBSS promoters;or (3) the first promoter is a GBSS promoter and the second promoter is an ADP glucose pyrophosphorylase (AGP) promoter. 13. A method of reducing expression of a gene normally capable of being expressed in a plant cell, comprising exposing a plant cell to the construct of claim I, wherein the construct is CA 02581440 2016-08-23 maintained in a bacterial strain which is: Agrobacterium tumefaciens, Rhizobium trifolii, Rhizobium leguminosarum, Rhyllobacterium myrsinacearum, SinoRhizobium meliloti, or MesoRhizobium loti, wherein the first polynucleotide comprises a sequence that shares sequence identity to a target gene sequence in the plant cell genome. 14. A construct comprising an expression cassette which comprises in the 5' to 3' orientation (i) a first promoter, (ii) a first polynucleotide that comprises a sequence that shares sequence identity with a promoter sequence associated with a target gene for at least 23 contiguous nucleotides, (iii) a second polynucleotide, wherein the second polynucleotide and the first polynucleotide are fully identical in sequence over at least 23 contiguous nucleotides, wherein the second polynucleotide is positioned within the cassette in a different orientation to the first polynucleotide, and (iv) a second promoter, wherein the first promoter is operably linked to the 5'-end of the first polynucleotide and the second promoter is operably linked to the 3'-end of the second polynucleotide, and wherein neither the first polynucleotide nor the second polynucleotide is operably linked to a terminator, and wherein the direction of transcription initiated from the first promoter is toward the second promoter and the direction of transcription initiated from the second promoter is toward the first promoter. 15. The transformation plasmid of claim 9, comprising the sequence depicted in SEQ ID NO: 40 or 42. 16. A method for reducing cold-induced sweetening in a tuber, said method comprising expressing the construct as defined in any one of claims 1 to 5 in a cell of a tuber, wherein (a) the first polynucleotide comprises the sequence that shares sequence identity with at least a part of an R1 gene or with at least a part of an R1 gene promoter, (b) one or both of the first and second promoters are granule-bound starch synthase (GBSS) or ADP glucose pyrophosphorylase (AGP), and (c) expression of the construct in the cell reduces transcription and/or translation of an R1 gene in the tuber cell genome, thereby reducing cold-induced sweetening in the tuber. 17. The method of claim 16, wherein the first polynucleotide comprises the sequence depicted in SEQ ID NO: 23 or 24. 18. A method for enhancing tolerance to black spot bruising in a tuber, said method comprising expressing the construct as defined in any one of claims 1 to 5 in a cell of a tuber, wherein (a) the first polynucleotide comprises the sequence that shares sequence identity with at CA 02581440 2016-08-23 least a part of a tuber-expressed polyphenol oxidase gene or a tuber-expressed polyphenol oxidase gene promoter, (b) one or both of the first and second promoters are granule-bound starch synthase (GBSS) or ADP glucose pyrophosphorylase (AGP), and (c) expression of the construct in the cell reduces transcription and/or translation of a polyphenol oxidase gene in the tuber cell genome, thereby enhancing the tolerance of the tuber to black spot bruising. 19. The method of claim 18, wherein the first polynucleotide comprises the sequence of SEQ ID NO: 26 or 27. 20. A method for increasing oleic acid levels in an oil-bearing plant, said method comprising expressing the construct as defined in any one of claims 1 to 5 in a cell of a seed of an oil-bearing plant, wherein (a) the first polynucleotide comprises a sequence that shares sequence identity with at least a part of a fatty acid desaturase (Pad2) gene or a Fad2 gene promoter, (b) one or both of the first and second promoters are napin gene, Fad2 gene, or stearoyl-ACP desaturase gene promoters, and (c) expression of the construct in the cell reduces transcription and/or translation of a Fad2 gene in the cell of the seed of the oil-bearing plant, thereby increasing the oil content of the seed. 21. The method of claim 20, wherein (i) the first polynucleotide comprises the sequence depicted in SEQ ID NO: 28 or a sequence that shares sequence identity with at least a part of SEQ ID NO: 28;(ii) the sequence of the napin gene promoter comprises the sequence depicted in SEQ ID NO: 30;(iii) the sequence of the stearoyl-ACP desaturase gene promoter comprises the sequence depicted in SEQ ID NO: 31;(iv) the sequence of the fatty acid desaturase (Fad2) gene promoter comprises the sequence depicted in SEQ ID NO: 32;or (v) permutations of (i)-(iv) exist in the construct. 22. The method of claim 20 or 21, wherein the oil-bearing plant is a Brassica plant, canola plant, soybean plant, cotton plant, or a sunflower plant. 23. A method for reducing lignin content in a plant, said method comprising expressing the construct as defined in any one of claims 1 to 5 in a cell of the plant, wherein (a) the first polynucleotide comprises a sequence that shares sequence identity with at least part of the sequence of the promoter associated with a gene which is caffeic acid/5-hydroxyferulic acid 3/5O-methyltransferase (COMT) gene or caffeoyl CoA 3-O-methyltransferase (CCOMT) gene, (b) one or both of the first and second promoters are petH or Pal gene promoters, and (c) expression CA 02581440 2016-08-23 of the construct in the cell reduces transcription and/or translation of a COMT or CCOMT gene in the cell of the plant, thereby reducing lignin content in a plant. 24. The method of claim 23, wherein the plant is an alfalfa plant and wherein the first polynucleotide comprises at least a part of the sequence depicted in SEQ ID NO: 33 or 37. 25. A method for reducing the degradation of pectin in a fruit of a plant, said method comprising expressing the construct as defined in any one of claims 1 to 5 in a fruit cell of the plant, wherein (a) the first polynucleotide comprises the sequence of part of polygalacturonase gene, (b) both of the first and second promoters are fruit-specific promoters, and (e) expression of the construct in the fruit cell reduces transcription and/or translation of a polygalacturonase gene in the cell of the plant, thereby reducing the degradation of pectin in the fruit. 26. The method of claim 25, wherein the first polynucleotide comprises the sequence depicted in SEQ ID NO: 39 or at least a part of the sequence depicted in SEQ ID NO: 39. 27. A method for reducing the allergenicity of a food produced by a plant, said method comprising expressing the construct as defined in any one of claims 1 to 5 in a cell of a plant, wherein (a) the first polynucleotide comprises the sequence of part of a gene that encodes an allergen, and (b) the expression of the construct reduces transcription and/or translation of the allergen, thereby reducing the allergenicity of a food produced by the plant. 28. The method of claim 27, wherein: (1) (a) the plant is an apple plant, (b) the food is an apple, (c) the first polynucleotide comprises a sequence from the Mal d 1 gene promoter, and (d) expression of the construct in the apple plant reduces transcription and/or translation of Mal d I in the apple;
  2. 2
    (2) (a) the plant is a peanut plant, (b) the food is a peanut, (e) the first polynucleotide comprises a sequence from the Ara h 2 gene promoter, and (d) expression of the construct in the peanut plant reduces transcription and/or translation of Ara h 2 in the peanut; or (3) (a) the plant is a soybean plant, (b) the food is a soybean, (c) the first polynucleotide comprises a sequence from the Gly m Bd gene promoter, and (d) expression of the construct in the soybean plant reduces transcription and/or translation of Gly m Bd in the soybean. CA 02581440 2016-08-23 29. A method for downregulating the expression of multiple genes in a plant, said method comprising expressing in a cell of a plant:(1) the construct of claim 1, comprising the sequence that shares sequence identity with at least a part of the sequence depicted in SEQ ID NO: 40, which downregulates expression of polyphenol oxidase, phosphorylase L gene, and the R1 gene in the plant cell;or (2) the construct of claim 1, comprising the sequence depicted in SEQ ID NO: 42, which downregulates expression of polyphenol oxidase, phosphorylase L gene, and the R1 gene in the plant cell. 30. The method of claim 20, wherein the first polynucleotide comprises a sequence that shares sequence identity with (i) at least part of the sequence depicted in SEQ ID NO: 28;or (ii) at least part of the sequence of the promoter associated with the napin gene depicted in SEQ ID NO: 30;or (iii) at least part of the sequence of the stearoyl-ACP desaturase gene promoter depicted in SEQ ID NO: 31;or (iv) at least part of the sequence of the fatty acid desaturase (Fad2) gene promoter depicted in SEQ ID NO: 32, or permutations of (i)-(iv) exist in the construct.