A team led by Ram Dixit at Washington University in St. Louis investigated how normal root twisting arises. The work, published in Nature Communications and coming from the Center for Engineering Mechanobiology (CEMB), tested whether twisting needs a full loss of gene function or only a localized change in gene expression.
Using a model plant whose roots skew right or left, the researchers expressed the wild-type version of a key gene in specific root cell layers. Expressing the gene in inner layers left plants twisted, while expressing it only in the outer epidermis restored straight root growth. That result showed the epidermis can control twisting across the organ.
Mechanobiology experiments and modelling explained why. Charles Anderson’s lab measured changes in the orientation of cellulose microfibrils in mutant roots, and engineer Guy Genin made a computer model showing concentric layers act like rings in a trunk: the outer ring has more leverage. The authors note this insight could guide engineering root architecture for crops in challenging soils.
Difficult words
- investigate — to study carefully to discover factsinvestigated
- epidermis — the outer cell layer of a plant root
- express — to make a gene active in certain cellsexpressed, expressing
- wild-type — the normal, non-mutated version of gene
- mutant — an organism with a changed gene or genes
- microfibrils — very small fibers in plant cell walls
- mechanobiology — study of how physical forces affect biology
- concentric — having shapes with the same center, different sizes
- leverage — ability to cause greater mechanical effect or force
- architecture — the arrangement or design of a structure
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Discussion questions
- Do you think changing gene expression in the epidermis is a good way to control root growth? Why or why not?
- How could stronger or different root architecture help farmers in soils that are hard to grow crops in? Give one or two reasons.
- What practical problems might scientists face when engineering plant roots for use in real fields?
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