Scientists Solve the Grass Leaf Conundrum
upstart writes:
watching the grass grow and how 19th century scientists were right
Scientists solve the grass leaf conundrum:
Grass is cut regularly by our mowers and grazed on by cows and sheep, yet continues to grow back.
The secret to its remarkable regenerative powers lies in part in the shape of its leaves, but how that shape arises has been a topic of longstanding debate.
[...] Flowering plants can be categorised into monocots and eudicots. Monocots, which include the grass family, have leaves that encircle the stem at their base and have parallel veins throughout.
Eudicots, which include brassicas, legumes and most common garden shrubs and trees, have leaves that are held away from the stem by stalks, termed petioles, and typically have broad laminas with net-like veins.
In grasses, the base of the leaf forms a tube-like structure, called the sheath. The sheath allows the plant to increase in height while keeping its growing tip close to the ground, protecting it from the blades of lawnmowers or incisors of herbivores.
[...] They modelled different hypotheses for how grass leaves grow, and tested the predictions of each model against experimental results.
To their surprise, they found that the model based on the 19th century idea of sheath-petiole equivalence was much more strongly supported than the current view.
[...] The grass study shows how simple modulations of growth rules, based on a common pattern of gene activities, can generate a remarkable diversity of different leaf shapes, without which our gardens and dining tables would be much poorer.
Journal Reference:
A. E. Richardson, J. Cheng, R. Johnston, et al. Evolution of the grass leaf by primordium extension and petiole-lamina remodeling, Science (DOI: https://www.science.org/doi/10.1126/science.abf9407)
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