SPS-ØØØW8-4 - Innate™ Russet Burbank Potato | BCH-LMO-SCBD-109066 | Living Modified Organism | Biosafety Clearing-House

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Living Modified Organism (LMO)

Decisions on the LMO Risk Assessments  
last updated: 22 Jun 2022
Living Modified Organism identity
The image below identifies the LMO through its unique identifier, trade name and a link to this page of the BCH. Click on it to download a larger image on your computer. For help on how to use it go to the LMO quick-links page.
Innate™ Russet Burbank Potato
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W8
SPS-ØØØW8-4
  • - Organization: J.R. Simplot Company () | BCH-CON-SCBD-106427-1
    Organization
    J.R. Simplot Company ()
    Private sector (business and industry)
    5369 West Irving Street
    Boise, ID
    83706, United States of America
    Phone: +1 (208) 780-6066,
    Fax:
    Email:
    Website:
The potato (Solanum tuberosum) was modified to express a resistance gene against late blight (Phytophthora infestans) and RNA interference cassettes to reduce enzymatic browning, formation of dark spots, lower the acrylamide potential and allow for cold storage. The resistance gene from Solanum venturii recognizes a pathogen-specific effector protein to cause a defense response to halt the spread of infection. To reduce discoloration (enzymatic browning) due to damage from harvesting and transport, polyphenol oxidase-5 was silenced. To lower the acrylamide potential, asparagine synthetase (reduced free asparagine), water dikinase (lower levels of reducing sugars) and phosphorylase-L (lower levels of reducing sugars) were silenced. Thus, when baked or fried, it is expected that less free asparagine and reducing sugars will react (via the Millard reaction) to form acrylamide. Further, invertase was additionally silenced to reduce the conversion of sucrose into reducing sugars, which may also allow the potatoes to be stored at colder temperatures, thus, potentially reducing sprout inhibiting chemicals and growth of disease. Silencing is not expected to change the levels of essential amino acids or other nutrients in the potato.
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The term “Recipient organism” refers to an organism (either already modified or non-modified) that was subjected to genetic modification, whereas “Parental organisms” refers to those that were involved in cross breeding or cell fusion.
  • BCH-ORGA-SCBD-12106-6 Organism Solanum tuberosum (Potato, SOLTU)
    Crops
  • BCH-LMO-SCBD-260756-1 Living Modified Organism SPS-ØØE56-7 - Low acrylamide potential, reduced browning Russet potato
    J.R. Simplot Company | Changes in quality and/or metabolite content (Carbohydrates, Pigmentation / Coloration, Protein and amino acids)
Variety Russet Burbank
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Characteristics of the modification process
pSIM1278 and pSIM1678
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  • Agrobacterium-mediated DNA transfer
Some of these genetic elements may be present as fragments or truncated forms. Please see notes below, where applicable.
The modified potato was produced through two subsequent transformation events; first with pSIM1278 (to generate E56 potato) and then pSIM1678 (to generate W8 potato).

DNA insert from E56 vector pSIM1278
The parental LM potato line contains two types of RNA interference cassettes:

  1. The first RNA interference cassette suppresses expression of asparagine synthetase-1 (asn1 from Solanum tuberosum) and polyphenol oxidase 5 (ppo5 from Solanum verrucosum). Transcription of the cassette occurs from two converging promoters: S. tuberosum ADP glucose pyrophosphorylase and  granule-bound starch synthase (convergent orientation). The transcription contains inverted repeats of fragments of asn1 and ppo5, separated by a spacer region.
  2. The second RNA interference cassette suppresses expression of phosphorylase-L promoter (PhL from S. tuberosum) and alpha-glucan water dikinase R1 gene promoter (P-R1 from S. tuberosum). Transcription of the cassette occurs from two converging promoters: S. tuberosum ADP glucose pyrophosphorylase and  granule-bound starch synthase (convergent orientation). The transcription contains inverted repeats of fragments of P-R1 and PhL, separated by a spacer region.

Due to complex rearrangements which occurred during the insertion of the T-DNA, the genome contains two tandem repeats of asn1/P-po5 silencing cassettes (three in total) and three partial tandem repeats of the PhL/R1 silencing cassette in addition to the expected insert containing the two RNAi cassettes. 

Expected sizes for genetic elements (as per pSIM1278 vector):
  • Cassette 1:
    •  ADP glucose pyrophosphorylase gene promoter - 2260 basepairs (bp)
    • asn1 - 405 bp
    • ppo5 - 144 bp
    • Spacer-1 - 157 bp
    • asn1 - 406 bp
    • Granule bound starch synthase gene promoter - 686 bp
  • Cassette 2:
    • ADP glucose pyrophosphorylase gene promote - 2260 bp
    • PhL - 509 bp
    • R1 - 532 bp
    • Spacer-2 - 258 bp
    • Granule bound starch synthase gene promoter - 924 bp

DNA insert from vector  pSIM1678
The DNA insert associated with pSIM1678 contains two gene cassettes: Solanum venturii late blight (Phytophthora infestans) resistance gene 1 (Rpi-vnt1) and S. tuberosum vacuolar invertase RNAi cassette.

The Rpi-vnt1 coding sequence is under control of the native promoter and terminator from S. venturii.

The RNAi cassette suppresses the expression of vacuolar invertase (inv), which contains inverted repeats of inv separated by a short connector sequence. Transcription of the cassette occurs from two converging promoters: S. tuberosum ADP glucose pyrophosphorylase and  granule-bound starch synthase (convergent orientation).

Expected sizes for genetic elements (as per pSIM1678 vector):
  • Cassette 1:
    •  Rpi-vnt1 promoter - 709 bp
    • Rpi-vnt1 coding sequence - 2676 bp
    • Rpi-vnt1 terminator - 1025 bp
  • Cassette 2:
    • ADP glucose pyrophosphorylase gene promote - 2261 bp
    • inv - 679 bp
    • Spacer - 6 bp
    • inv - 504 bp
    • Granule bound starch synthase gene promoter - 924 bp

Notes
  • Southern blot analysis indicated that the W8 genome contains a single integration of both pSIM1278 and pSIM1678 vectors.
  • The DNA insert from pSIM1278 is likely integrated into chromosome 2.
  • The DNA insert of pSIM1678 contains a nearly intact DNA insert with a 330-bp deletion, which removes the entire T-DNA left border and 137-bp of the Rpi-vnt1 promoter. 
  • Southern blot and PCR analyses have shown that the Russet Burbank W8 event does not contain backbone from either plasmid used in the transformations.
  • Due to the RNAi response, no proteins are expected to be translated from the RNAi cassettes.

For more information, also refer to the parental E56 potato record.
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LMO characteristics
After transcription from either of the convergent promoters, the nascent mRNA will fold on itself due to complementary base-pairing between the inverted repeat sequences and form a double-stranded structure (hairpin RNA; hpRNA). The double-stranded structure of the hpRNA will trigger an RNA interference response. Dicer-like proteins will complex with the hpRNA, processing it into small interfering RNA (siRNA), roughly 21 to 23 bp in length. After associating with Agronaute family proteins, mRNA transcripts with sequences complementary to the siRNA will targeted for degradation. Thus, the expression of the endogenous asparagine synthetase, polyphenol oxidase, phosphorylase-L, water dikinase and vacuolar invertase will be silenced.
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  • Food
Detection method(s)
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Additional Information
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Record type Field Record(s)