Cassava brown streak disease-resistant cassava | BCH-LMO-SCBD-115143 | Living Modified Organism | Biosafety Clearing-House

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Living Modified Organism (LMO)

Decisions on the LMO Risk Assessments  
last updated: 21 Jan 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.
Cassava brown streak disease-resistant cassava
EN
D5001-985013
Cassava (Manihot esculenta Crantz) was modified for RNA interference-mediated resistance to Cassava Brown Streak Disease. The modified cassava expresses a hairpin RNA (hpRNA) cassette that contains portions of the coat proteins of Cassava brown streak virus and Ugandan cassava brown streak virus, the causal agents of Cassava Brown Streak Disease. Transcription of the hpRNA form this cassette guides host cell machinery for targeted degradation of infecting viral transcripts.

A selectable marker, Escherichia coli neomycin phosphotransferase II, was also included for selection of transformants using kanamycin.
EN
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.
Cassava cultivar: TMS 98/0505
EN
  • Viral resistant cassava with increased levels of zinc and iron
    | Dr Ihuoma Okwuonu | Changes in quality and/or metabolite content, Increased iron levels, Increased zinc levels, Resistance to antibiotics (Kanamycin), Resistance to CBSV, Resistance to diseases and pests (Viruses), Resistance to UCBSV, Selectable marker genes and reporter genes
  • Viral resistant cassava with increased levels of zinc and iron
    | National Root Crops Research Institute(NRCRI) | Changes in quality and/or metabolite content, Increased iron levels, Increased zinc levels, Resistance to antibiotics (Kanamycin), Resistance to CBSV, Resistance to diseases and pests (Viruses), Resistance to UCBSV, Selectable marker genes and reporter genes
Characteristics of the modification process
p5001
EN
  • Agrobacterium-mediated DNA transfer
Some of these genetic elements may be present as fragments or truncated forms. Please see notes below, where applicable.
RNA interference cassette:
Transcription of the cassette produces a hairpin RNA (hpRNA). RNA polymerase is recruited to the Cassava vein mosaic virus promoter and then transcribes: two segments of Cassava brown streak virus (CBSV) and the Ugandan cassava brown streak virus (UCBSV) coat protein (sense orientation), the Flaveria trinervia pyruvate orthophosphate dikinase intron 3 (pdk), and CBSV and UCBSV coat protein (anti-sense orientation). Transcription stops at the Agrobacterium tumefaciens nopaline synthase (nos) terminator. The produced RNA then can form a double stranded segment due to the inter-strand homology between the CBSV and UCBSV coat protein segments in inverted orientations and the flexible linker/loop, pdk. The double stranded segment of the hpRNA is sufficient to elicit an RNA interference (RNAi) response. The host cell machinery then processes the hpRNA into small interfering RNA, which is used to guide the targeted degradation of RNA molecules with sequence homology. In this case, infecting viral transcripts are degraded by the host cell.

Please note all genetic elements were in the anti-sense orientation.
EN
LMO characteristics
EN
  • Food
  • Research
Detection method(s)
Due to the processing of the hpRNA by the host cell DICER protein, it is expected that small interfering RNA 21 to 24 base pairs in length will be present instead. Additionally, the cellular processing means that no proteins are expected to be produced from the hpRNA.
EN
Additional Information
Please note that several lines have been created using the transformation vector p5001. The following transformation events are expected to contain similar genetics:

D5001-985013, D5001-985019, D5001-985022, D5001-985024, D5001-985025, D5001-985026, D5001-985028, D5001-985029, D5001-985030, D5001-985031, D5001-985033 and D5001-985034.

The transformation event is thus a placeholder until further information is uncover and/or a line has been selected for commercialization.
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