The Vitamin Map


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Improve speed on the Piccadilly Line, create delays on the track to Hyde Park Corner, route more trains through Kings Cross. These are not suggestions for baffling passengers of the London Underground. Rather, it’s a metaphor describing how plant scientists may one day breed new varieties: To enhance the breeding process, they may consult plant metabolism models that resemble the familiar map of the London Tube.

Tube map for plants
Creating such metabolic models, which simulate the network of biochemical reactions in the plant, is extremely challenging because plant metabolism involves thousands of enzymes and is extremely complex. A new plant metabolic model, the most complete to date, has recently been created by a team headed by scientists from the Weizmann Institute, the Technion – Israel Institute of Technology and Tel Aviv University. This computerized model, described in the Proceedings of the National Academy of Sciences, USA, focuses on Arabidopsis, a plant in the mustard family that is commonly used in research. The network of this plant’s metabolic reactions is so wide and branched that it indeed evokes the layout of an extensive underground system, in which the lines represent the pathways of metabolic reactions, the trains symbolize individual enzymes and the ends of the lines – the reactions’ end products.
Applied to the breeding of plants, the model might predict, for example, that the best way to increase the production of a desired nutrient, say vitamin E, is to close a particular “train line” – that is, block a certain biochemical reaction in the plant, or to increase “traffic” on another line – that is, speed up another reaction. Armed with such predictions – the technical term is “predictive metabolic engineering” – plant breeders should be able to produce desired new varieties more quickly and efficiently than by trial and error, as has been done in the past.
Prof. Asaph Aharoni
The new model has been created by Prof. Asaph Aharoni and Ph.D. student Shira Mintz-Oron of the Weizmann Institute’s Plant Sciences Department, Dr. Tomer Shlomi of the Technion and Prof. Eytan Ruppin of Tel Aviv University. The team also included the Institute’s Ph.D. student Sergey Malitsky and Aharoni’s lab assistant Dr. Sagit Meir.

Though the model was developed for Arabidopsis, it is applicable to many other plants as well. Among the projects to which Aharoni and his colleagues now intend to apply it is the breeding of new crops, such as rice that is rich in vitamin B1. Crops fortified in this way might in the future help prevent serious vitamin deficiencies that affect people in developing countries.

Prof. Asaph Aharoni’s research is supported by the Tom and Sondra Rykoff Family Foundation; Roberto and Renata Ruhman, Brazil; the Clore Center for Biological Physics; the Minna James Heineman Stiftung; and the Kahn Family Research Center for Systems Biology of the Human Cell. Prof. Aharoni is the incumbent of the Peter J. Cohn Professorial Chair.