Cassava mosaic disease resistant cassava | BCH-LMO-SCBD-115621 | Living Modified Organism | Biosafety Clearing-House

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Living Modified Organism (LMO)

Decisions on the LMO Risk Assessments  
last updated: 26 Jun 2020
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 mosaic disease resistant cassava
EN
pCRNAi-dsAC1dsAV1_singleintron
No
The cassava was modified for resistance to Cassava mosaic disease (CMD) by introducing an RNA interference cassette that targets African cassava mosaic virus (ACMV) replication associated disease AC1 and capsid protein (AV1). The production of hairpin RNA by the host cells trigger an RNAi response that is expected to target viral transcripts and prevent viral replication and thus further infection. Due to conservation between AC1 and AV1 sequences in ACMV and East african cassava mosaic virus, the modified cassava is expected to resistant to both viruses, which are the causal agents of CMD. A selectable marker, Escherichia coli hygromycin B phosphotransferase, was additionally included for hygromycin selection during transformation.
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.
EN
  • Cassava mosaic disease resistant cassava
    | Masinde Muliro University of Science and Technology(MMUST) | Resistance to African cassava mosaic virus (ACMV), Resistance to antibiotics (Hygromycin), Resistance to diseases and pests (Viruses), Selectable marker genes and reporter genes
  • Cassava mosaic disease resistant cassava
    | Masinde Muliro University of Science and Technology(MMUST) | Resistance to African cassava mosaic virus, Resistance to antibiotics (Hygromycin), Resistance to diseases and pests (Viruses), Selectable marker genes and reporter genes
  • Cassava mosaic disease resistant cassava
    | Masinde Muliro University of Science and Technology(MMUST) | Resistance to African cassava mosaic virus, Resistance to antibiotics (Hygromycin), Resistance to diseases and pests (Viruses)
  • Cassava brown streak disease resistant cassava
    | Masinde Muliro University of Science and Technology(MMUST) | Resistance to antibiotics (Hygromycin), Resistance to Cassava brown streak virus, Resistance to diseases and pests (Viruses), Selectable marker genes and reporter genes
Characteristics of the modification process
pCAMBIA1300
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
The modified cassava contains an RNA interference (RNAi) cassette designed to target African cassava mosaic virus replication associated gene (AC1) and capsid protein (AV1). Transcription is initiated from the Cauliflower mosaic virus (CaMV) 35S promoter and terminates at the CaMV 35S terminator. The transcript contains two segments (sense and antisense) of AC1 separated by a plant synthetic intron. The sense AC1 sequence is preceded by an AV1 antisense sequence and the antisense AC1 is followed by a sense AV1 sequence. Post-transcription, the intron functions as a loop and allows the sense and antisense segments of AC1 and AV1 to base pair, forming hairpin RNA (hpRNA). The hpRNA acts as double stranded RNA (dsRNA), which triggers an RNAi response and the host cell machinery will target AC1 and AV1 viral transcripts for degradation.

Note:
- The segment of AC1 corresponds to position 1690 to 1844 of the ACMV DNA 1 (DNA A) (GenBank accession AJ427910).
- The segment of AV1 corresponds to position 492 to 647 of the ACMV DNA 1 (DNA A) (GenBank accession AJ427910).
- The source of the AC1 and AV1 sequences is ACMV strain Nigeria-Ogo.
- Due to the RNAi response, no protein is expected to be translated from the RNAi cassette.

Selectable marker
Transcription of Escherichia coli hygromycin B phosphotransferase is under transcriptional control of the CaMV 35S promoter and terminator.
RNA interference
An RNAi response is an anti-viral response triggered by the recognition of dsRNA. Host DICER recognizes dsRNA, cleaving the dsRNA into small interfering RNA (siRNA), roughly 21-23 bp long (size is host dependent). The siRNA is then bound by ARGONAUTE family proteins, which unwind the duplex, leaving a single strand of the siRNA and activating the RISC complex. The RISC complex targets transcripts with homology to the siRNA and degrades them.
EN
LMO characteristics
EN
  • Food
Detection method(s)
EN
Additional Information
RNA interference
An RNAi response is an anti-viral response triggered by the recognition of dsRNA. Host DICER recognizes dsRNA, cleaving the dsRNA into small interfering RNA (siRNA), roughly 21-23 bp long (size is host dependent). The siRNA is then bound by ARGONAUTE family proteins, which unwind the duplex, leaving a single strand of the siRNA, and activating the RISC complex. The RISC complex targets transcripts with homology to the siRNA and degrades them.
EN
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