Presentation: GROUP 3 - Genetic Engineering of Fruit Ripening to Prevent Spoilage

http://www.biotopics.co.uk/edexcel/biotechnol/frurip.html

Researchers have managed to modify tomato plants by inserting a gene which prevents one of the plant's 'ripening' genes from working at the usual rate. The tomatoes may then be left on the plant until red to develop a full flavour. They soften more slowly, suffer less damage in transit and have a much longer shelf life, cutting out waste.

ethene gas = promotes fruit ripening
in the USA, whole tomatoes (marketed as Flavr SavrTM are produced in this way

Zeneca in the UK, a gene for stage Y (pectinase enzyme) is inhibited., probably better because it's lower down the pathway so less lethal mutations

http://books.google.ca/books?id=1AvyrJOYStkC&pg=PA340&lpg=PA340&dq=Genetic+Engineering+of+Fruit+Ripening+to+Prevent+Spoilage&source=bl&ots=xzIp_wsEdt&sig=0_hsDveavc-HJwQJ2HsN7mYYpYM&hl=en&ei=66p1S-G3BpCcswO0tYnMCA&sa=X&oi=book_result&ct=result&resnum=2&ved=0CAoQ6AEwAQ#v=onepage&q=Genetic%20Engineering%20of%20Fruit%20Ripening%20to%20Prevent%20Spoilage&f=false
So tomatos have been engineered not to produce ethylene, and so it won't ripe, then during the transport process, tomatos are sprayed with ethylene gas to promote artificial ripening.

This was done by creating an antisense mRNA for the ACC synthase gene (the precursor of ethylene) 'Endless summer variety'

gene subtraction - polygalacturonase

http://answers.yahoo.com/question/index?qid=20090315040540AALXSNU
Most fruit first become ripened because of the release of a hormone within the fruit and the plant called ethylene (H2C=CH2). Ethylene causes the breakdown which in itself causes a production of enzymes that break down the structures of the fruit (eg.: amylase, pictenase).The eyhylene gas also destroys the green pigment of the fruit chlorophyll. But for any fruit to become ripened there needs to be a high enough concentration of ethylene around the fruit to even begin to ripen.

The amylase acts on the starches, which are made of amylose, which is just a long chain of glucose molecule. And what the amylase does is it cuts the bonds of the starch chain, so then the glucose molecules are free; and now the fruit tastes sweet.
The other enzyme pectinase does almost the exact same thing as amylase, it cuts away the bonds of the pectin molecule so now we have a bunch of pectinic acid, and now the fruit is soft enough to eat. Pectin is extremely important for a fruits/plants because it hold the cells together.

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2705034/?tool=pmcentrez&report=abstract
Ripening-Regulated Susceptibility of Tomato Fruit to Botrytis cinerea Requires NOR But Not RIN or Ethylene1[W][OA]
Dario Cantu, Barbara Blanco-Ulate, Liya Yang, John M. Labavitch, Alan B. Bennett, and Ann L.T. Powell*

http://www.ncbi.nlm.nih.gov/sites/entrez?Db=pmc&Cmd=DetailsSearch&Term=(%22fruit%22[MeSH+Terms]+OR+fruit[Acknowledgments]+OR+fruit[Figure%2FTable+Caption]+OR+fruit[Section+Title]+OR+fruit[Body+-+All+Words]+OR+fruit[Title]+OR+fruit[Abstract]+OR+fruit[Author])+AND+ripening[All+Fields]

http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=2671613&tool=pmcentrez&rendertype=abstract

http://jxb.oxfordjournals.org/cgi/content/abstract/53/377/2039
Ethylene biosynthesis and action in tomato: a model for climacteric fruit ripening
Received 11 April 2002; Accepted 2 July 2002
Lucille Alexander and Don Grierson1

http://jxb.oxfordjournals.org/cgi/content/abstract/53/377/1995
P. J. White
Recent advances in fruit development and ripening: an overview
J. Exp. Bot., October 1, 2002; 53(377): 1995 - 2000.