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Modified Organism
Cassava modified for high starch yield, increased photosynthetic capacity, and ACMV resistance
Record information and status
Record ID
114704
Status
Published
Date of creation
2019-05-20 19:35 UTC (austein.mcloughlin@cbd.int)
Date of last update
2019-05-20 20:17 UTC (austein.mcloughlin@cbd.int)
Date of publication
2019-05-20 20:17 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 modified for high starch yield, increased photosynthetic capacity, and ACMV resistance
Transformation event
Not available
Developer(s)
International Institute of Tropical Agriculture (IITA)
IITA Headquarters
PMB 5320, Oyo Road, Ibadan 200001,
Oyo State, Nigeria.
Ibadan, Oyo State
Nigeria
Phone:+234 700800IITA
Fax:+44 208 7113786
Email:iita@cgiar.org
Url:International Institute of Tropical Agriculture
Description
The cassava has been modified to elevate the storage root yield, increase photosynthesis, and have RNA interference-mediated resistance to African Cassava Mosaic Virus (ACMV). The expression of PsGPTand AtNTT  promote starch biosynthesis in the amyloplasts through the increased uptake of both ATP and glucose-6-phosphate precursors. The cassava also has been modified for increased photosynthetic capacity via EcGlyDH, which creates a photorespiratory bypass, and AtTMT1, which increases expression of photosynthetic genes and increases sugar export to the storage roots. The plant is also resistant to ACMV through the production of hairpin RNA targeting AC1, mediating an RNA interference against the virus and preventing viral replication.
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
Cultivar 60444
Related LMOs
Cassava modified for increased starch yield, elevated photosynthesis, and ACMV resistance
Altered photosynthesis Changes in physiology and/or production - Yield, Growth rate, Photoperiod response Changes in quality and/or metabolite content - Carbohydrates Resistance to antibiotics - Hygromycin Resistance to diseases and pests - Viruses Selectable marker genes and reporter genes
Cassava modified for high starch yield, increased photosynthetic capacity, and ACMV resistance
Altered photosynthesis Changes in physiology and/or production - Yield, Growth rate, Photoperiod response Changes in quality and/or metabolite content - Carbohydrates Changes to photosynthesis and photorespiration Increased photosynthetic rate Resistance to antibiotics - Hygromycin Resistance to diseases and pests - Viruses Selectable marker genes and reporter genes Tolerance to abiotic stress - Cold / Heat
Characteristics of the transformation process
Vector
p134GG
Techniques used for the modification
  • Agrobacterium-mediated DNA transfer
Genetic elements construct
 
Granule Bound Starch Synthase 1 Promoter
1.16 Kb
 
 
Glucose-6-phosphate/phosphate-translocator gene
1.28 Kb
 
 
Nopaline Synthase Gene Terminator
0.26 Kb
 
 
Solanum tuberosum Soluble Starch Synthase 3 promoter
1.02 Kb
 
 
5' Untranslated region from Cucumber Mosaic Virus 1
0.09 Kb
 
 
Nucleoside Triphosphate Translocator 1
1.87 Kb
 
 
Mannopine synthase gene terminator
0.25 Kb
 
 
L700 promoter
1.50 Kb
 
 
Omega 5' untranslated leader
0.07 Kb
 
 
Chloroplast Transit Peptide
0.19 Kb
 
 
Recombinant glycolate dehydrogenase (fused subunits DEF)
3.86 Kb
 
 
Octopine Synthase Gene Terminator
0.71 Kb
 
 
Ribulose 1,5-bisphosphate carboxylase/oxygenase small subunit 3B promoter
0.80 Kb
 
 
5' Untranslated region from Potato Virus X
0.07 Kb
 
 
Tonoplast Monosaccharide Transporter 1
2.20 Kb
 
 
Transcript 7 gene 3' untranslated region
0.22 Kb
 
 
Ribulose 1,5-bisphosphate carboxylase/oxygenase small subunit 2B promoter
0.70 Kb
 
 
Replication Associated Gene
0.17 Kb
 
 
Replication Associated Gene
0.17 Kb
 
 
CaMV 35S terminator
0.20 Kb
 
 
Nopaline Synthase Gene Promoter
0.31 Kb
 
 
Hygromycin B phosphotransferase gene
1.03 Kb
 
 
CaMV 35S terminator
0.22 Kb
 
Further details
Notes regarding the genetic elements introduced or modified in this LMO
Overexpression of PsGPT and AtNTT1 in roots:
The Pisum sativum Glucose 6-phosphate/Phosphate Translocator (PsGPT) is under the control of the Manihot esculenta Granule Bound Starch Synthase 1 promoter and the Agrobacterium tumefaciens nopaline synthase terminator.  Note: PsGPT contains both the 5' untranslated region (5' UTR) and the coding sequence.

Arabidopsis thaliana Nucleoside Triphoisphate Translocator 1 (AtNTT1) is transcribed from Solanum tuberosum Soluble Starch Synthase 3 promoter and the corresponding transcript is translated from the Cucumber Mosaic Virus 1 5' UTR. Transcription and translation terminate at the 3' untranslated region (3' UTR) of A. tumefaciens mannopine synthase.

PsGPT codes for a membrane-bound translocator that transports glucose-6-phosphate into the amyloplasts. Similarly, AtNTT1 encodes a translocator for transporting ATP into the amyloplasts. Starch biosynthesis is dependent on the presence of both glucose-6-phosphate and ATP. Thus, PsGPT and AtNTT1 together promote starch biosynthesis in the amyloplasts, leading to a greater accumulation of starch in the storage roots of the cassava plants.

Overexpression of EcGlyDH in leaves:
Escherichia coli Glycolate dehydrogenase (EcGlyDH) is a fusion of subunits D, E, and F. Transcription starts from Solanum tuberosum leaf specific 1 promoter, translation initiates from the 5' UTR of Tobacco Mosaic Virus, and termination occurs at the A. tumefaciens octopine synthase 3' UTR. The protein product is directed towards the chloroplast by the Nicotiana tabacum chloroplast transit peptide.

Elevated temperatures increase the likelihood of Ribulose-1,5-bisphosphate-caboxylase/-oxygenase (Rubisco) binding oxygen instead of carbon dioxide, which creates toxic 2-phosphoglycolate instead of 3-phosphoglycerate. In an ineffeicient and costly process termed photorespiration, 2-phosphoglycolate is converted to 3-phosphoglycerate. To mitigate the adverse effects of photorespiration, EcGlyDH acts as a bypass, creating carbon dioxide and glycerate from 2-phosphoglycolate in the plastids. The photorespiratory bypass increases photosynthetic efficiency, resulting in increased sugar and starch levels in the modified plant.

Overexpression of AtTMT1 in leaves:
A. thaliana Tonoplast Monosaccharide Transporter 1 (AtTMT1) is under transcriptional control of A. thaliana Rubsico Small Subunit 3B promoter, translational control of Potato Virus X 5' UTR, and A. tumefaciens Gene 7 terminator. AtTMT1 encodes a membrane protein responsible for transferring glucose from the cytosol into vacuole. Overexpression of AtTMT1 leads to an increased expression of photosynthetic genes, a decrease in sugar consumption for cellular respiration, a reduction of nocturnal carbon dioxide loss, and increased export capacity of sugars from the leaves. Elevated photosynthetic carbon fixation and sugar export to the roots, leads to increased yield.

RNA interference targeting ACMV:
The RNA interference (RNAi) cassette targets the African Cassava Mosaic Virus replication associated gene (AC1) through the production of hairpin RNA (hpRNA). Transcription commences from the A. thaliana Rubisco small subunit 2B promoter and transcribes an inverted repeat of sequences complementary to AC1, before terminating at the Cauliflower Mosaic Virus 35S terminator (CaMV 35 terminator). After transcription, the inverted repeat base pairs to form the hpRNA structure. The hairpin structure is similar to double stranded RNA, which then proceeds to elicit an RNAi response in the host plant. Following processing of the hpRNA, the host's RNAi proteins target viral transcripts with complementary base pairs to the AC1 inverted repeats. Thus, the RNAi response prevents viral replication and infection via the destruction of AC1, a gene essential for viral replication.

Selectable marker:
For the selection of transformed embryos, hygromycin B was used. E. coli Hygromycin B phosphotransferase is under the control of the Agrobacterium tumefaciens nopaline synthase
LMO characteristics
Modified traits
  • Selectable marker genes and reporter genes
  • Increased photosynthetic rate

Records referencing this document (2)
IDDescription
2record(s) found
Modified Organism2 records