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Modified Organism
Cassava mosaic disease resistant cassava
Record information and status
Record ID
115625
Status
Published
Date of creation
2020-06-26 14:06 UTC (austein.mcloughlin@cbd.int)
Date of publication
2020-06-26 14:06 UTC (austein.mcloughlin@cbd.int)

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.

LMO name
Cassava mosaic disease resistant cassava
Transformation event
pCRNAi-dsAC1
Developer(s)
Prof. Hassan Karakacha Were
Dean, School of Agriculture, Veterinary Science and Technology
Masinde Muliro University of Science and Technology (MMUST)
Kakamega
Kenya
Phone:(+254) (724) (972207)
Email:hwere@mmust.ac.ke
Description
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. 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 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.
Recipient Organism or Parental Organisms
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.
Manihot esculenta - Cassava, Brazilian arrowroot, Yuca, Manioc, Mandioca, MANES
Point of collection or acquisition of the recipient organism
Cassava cultivar TMS60444
Related LMOs
Cassava mosaic disease resistant cassava
Prof. Hassan Karakacha Were Resistance to antibiotics - Hygromycin Resistance to diseases and pests - Viruses Selectable marker genes and reporter genes
Cassava mosaic disease resistant cassava
Prof. Hassan Karakacha Were Resistance to antibiotics - Hygromycin Resistance to diseases and pests - Viruses Selectable marker genes and reporter genes
Cassava mosaic disease resistant cassava
Prof. Hassan Karakacha Were Resistance to antibiotics - Hygromycin Selectable marker genes and reporter genes
Cassava brown streak disease resistant cassava
Prof. Hassan Karakacha Were Resistance to antibiotics - Hygromycin Selectable marker genes and reporter genes
Characteristics of the transformation process
Vector
pCAMBIA1300
Techniques used for the modification
  • Agrobacterium-mediated DNA transfer
Genetic elements construct
 
CaMV 35S terminator
0.18 Kb
 
 
Hygromycin B phosphotransferase gene
1.03 Kb
 
 
CaMV Enhanced 35S promoter
0.68 Kb
 
 
CaMV 35S promoter
0.00 Kb
 
 
Replication Associated Gene
0.15 Kb
 
 
M27939 Intron Sequence
0.20 Kb
 
 
Replication Associated Gene
0.15 Kb
 
 
CaMV 35S terminator
0.00 Kb
 
Further details
Notes regarding the genetic elements introduced or modified in this LMO
RNA interference cassette
The modified cassava contains an RNA interference (RNAi) cassette designed to target African cassava mosaic virus replication associated gene (AC1). 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. Post-transcription, the intron functions as a loop and allows the sense and antisense segments of AC1 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 viral transcripts for degradation.

Note:
- The segment of AC1 corresponds to positions 1690 to 1844 of the ACMV genome (GenBank accession AJ427910).
- The source of the AC1 sequence is ACMV strain Nigeria-Ogo.
- The AC1 sequence is conserved between ACMV and East african cassava mosaic virus.
- 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.
LMO characteristics
Modified traits
  • Selectable marker genes and reporter genes
  • Resistance to African cassava mosaic virus (ACMV)
Common use(s)
  • Food
Additional Information
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.

Records referencing this document (4)
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Modified Organism4 records