DPS-Ø4Ø46–8 - Cassava brown streak disease-resistant cassava | BCH-LMO-SCBD-258946 | Living Modified Organism | Biosafety Clearing-House

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
The cassava (Manihot esculanta Crantz) was modified for resistance to Cassava Brown Streak disease caused by Cassava brown streak virus and Ugandan cassava brown streak virus. To achieve resistance, the cassava expresses an RNA interference cassette that targets the coat proteins of the two cassava viruses. In addition to the RNA interference cassette, the cassava contains an Escherichia coli neomycin phosphotransferase II cassette that was used for kanamycin (or neomycin) selection during transformation.
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 (Manihot esculanta Crantz) cultivar TME 204
  • Cassava brown streak disease-resistant cassava
    | National Root Crops Research Institute(NRCRI) | 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
  • 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 cassava contains a Cassava brown streak virus-Ugandan cassava brown streak virus RNA interference (RNAi) cassette and and Escherichia coli neomycin phosphotransferase II (nptII) gene cassette.

Transcription of the RNAi commences from a Cassava vein mosaic virus promoter and transcribes: a segment of the Cassava brown streak virus (CBSV) coat protein coding sequence (sense orientation); a segment of the the Ugandan cassava brown streak virus (UCBSV) coat protein coding sequence (sense orientation), a Flaveria trinervia pyruvate orthophosphate dikinase intron 3 (pdk), a CBSV coat protein (anti-sense orientation) and then an UCBSV coat protein segment (anti-sense orientation). Transcription is terminated at an Agrobacterium tumefaciens nopaline synthase terminator. After transcription, the sense and anti-sense sequences within the transcript base pair to form hairpin RNA with the pdk functioning as a flexible sequence to form the loop of the hairpin structure. The double stranded structure of the hpRNA elicits an RNAi response. Dicer-like endonucleases process the hpRNA into small interfering RNA (~21 to 23 nucleotdies in length), which are then recruited by Agronaute proteins to guide the targeted degradation of RNA molecules with sequence homology. In this case, infecting viral transcripts and genome ((+) single stranded RNA) are degraded by the host cell. Due to the processing of the hpRNA, no proteins are expected to be translated from this cassette.

Transcription of the nptII coding sequence is under control of a Cauliflower mosaic virus enhanced 35S promoter and an Agrobacterium tumefaciens nopaline synthase terminator.

  • The p5001 vector was produced from the pCAMBIA2300 vector.
  • A single, intact copy of the T-DNA is integrated at a single location in the cassava genome. No vector backbone sequences were integrated.
LMO characteristics
  • Food
Detection method(s)
Records referencing this document Show in search
Record type Field Record(s)
Country's Decision or any other Communication Living modified organism(s) 1
Risk Assessment generated by a regulatory process Living modified organism(s) 1