Welcome to our Food Safety blog =).

Created: 10 April 2010
Leader: Lynnette Heng
Members: Lorelle Ang
Soh Chin Yi
Goh Ai Ting
Li Yuen Ying

Lynnette: KK Hospital- Dietitian
Chin Yi: Gardenia- R&D
Ai Ting: Singapore Sports Council- Nutritionist
Yuen Ying: KH Roberts- lab assistant
Lorelle: OSIP (China)

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modification proces

- Based bacterial transformation system was used to modify the potatoes, where cells from the potato parental line were infused with a specifically constructed plasmid vector carried into each plant cell by the bacterial system.
-The vector carries the genetic code for resistance to the pests Colorado Potato Beetle (cry3A) and Potato Virus Y (PVYcp), and a marker gene for plant selection (nptII ). The Agrobacterium used in the transformation process is no longer considered a plant pest threat.
-The Agrobacterium containing the vector was added to potato stem sections into culture dishes and then transferred into the genome of individual potato cells thereby allowing selection on neomycin-containing media. Subsequently, the potato tissues were treated to regenerate the transgenic cells into shoots and tested for CPB and PVY resistance.


CRY3A gene and its encoded CRY3A protein
-Cry3A gene was isolated from the DNA of a strain of Bacillus thuriengensis subsp. tenebrionis (Btt).
-Upon ingestion it will disrupt cause the gut epithelium of the Colorado beetle to rupture causing the pest to die without harming the potato plant.


PVYcp gene
-PVY capsid protein gene (PVYcp) was obtained from a PVY strain isolated from potato.
-The gene sequence engineered into NewLeaf Y potato is identical to that of the native viral gene, except for a synthesized start codon.
-Studies conducted show that mRNA encoding for PVY proteins is produced in NewLeaf Y potato plants at levels well below that occurring in potato plants naturally infected with PVY.

marker gene NPTII
-To facilitate this process, a selectable marker gene, NPTII, and selective agent, kanamycin are incorporated into the growing media.
-cells that are selected for plant generation contains the NPTII and CRY3A genes.
-NPTII gene functions as a dominant selectable marker in the initial laboratory stages of plant cell selection after transformation.
-NPTII enzyme uses ATP to phosphorylate kanamycin to inactivate aminoglycoside antibiotics in the growth media to prevent them from killing the cells that produces NPTII.

(Safety Assessment of NewLeaf Y Potatoes Protected Against Colorado Potato Beetle and Infection by Potato Virus Y Causing Rugose Mosaic, 2002)
(http://www.agbios.com/docroot/decdocs/02-269-004.pdf)