Example of exercise for the model[MECHA] ( Example created by Valentin Couvreur and Valentine Calay (Faculty of Bio-Engineers, UCL)

Petite vidéo explicative sur MECHA:

The context

You are a researcher trying to discover a variety of millet that is more tolerant to drought. You suspect that aquaporins (water channels) are key regulators in increasing water availability for the plant through modification of root permeability. Little variability exists in genes regulating aquaporin expression in high-potential (“V0”) millet varieties. However, this variability exists in nature, and you can cross the high-potential variety with natural varieties (“V1-4”) to import new genes into the existing pool.

You have varieties with the following characteristics:

  • V1 : Increased expression of aquaporins in the epidermis (first cell layer on the root surface), doubling the permeability of epidermal membranes;

  • V2 : Increased expression of aquaporins in the cortex (tissue containing the largest cell surface area), doubling the permeability of cortical membranes;

  • V3: Increased expression of aquaporins in the endoderm (tissue supporting the Caspary frame), doubling the permeability of endodermal membranes;

  • V4: Increased expression of aquaporins in the Xylemic parenchyma (tissue surrounding the xylemic vessels), doubling the permeability of the membranes in the stele;

root cross section

Illustration by Fred Bouché []]

The questions

Creating a hybrid variety bringing together genes of interest requires a lot of time, and carrying out a preliminary study using a modeling tool makes it possible to test a priori which crossing would be the most promising to modify root permeability.

Use MECHA to answer the following questions and develop explanations:

  • What is the impact of endoderm suberization on root permeability?

  • Which hybrid (V0 - V?) would a priori allow the greatest increase in root permeability in the area with an unsuberized Caspary frame?

  • How does the permeability of this hybrid vary compared to the variety V0, in the more mature area where the endoderm is suberized?

  • What factors other than aquaporins limit root permeability?

Novel multiscale insights into the composite nature of water transport in roots
Couvreur V, Faget M, Lobet G, Javaux M, Chaumont F, Draye X

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