HASwith his “Four thorns nothing to protect her from the world”the rose of princelingWithout his knowledge, he had fostered a misunderstanding. In fact, no rose bush has thorns. The plant certainly has thorns, but they are thorns, recalled a study published on 1Ahem August in the magazine ScienceThe same is true for hawthorns, hollies, brambles, acacias, thistles… Other plant species, however, have real thorns: such as cacti, bougainvilleas, gorse, lemon trees or palm trees, but also raspberries, strawberries, apple trees or wild pear trees.
The difference, we grant you, is not obvious. However, there is something about it that arouses curiosity. A simple experiment will allow you to distinguish them; however, be careful with your hands. “If one of these sharp points comes off easily without tearing the fibers of the plant, it is a sting; otherwise, it is a thorn.”explains Mohammed Bendahmane, research director at Inrae at ENS Lyon and co-author of the study.
Botanists rely on the origin of the tissue of these spines to differentiate them. The sting thus arises from a layer of cells located just below the epidermis of the plant. The spine comes from a vascularized plant organ – stem, leaf, root, etc. – that has undergone metamorphosis. It is one with the rest of the plant, so it cannot be separated from it without suffering damage.
Thorns or stings, to know their function, it is not worth deciding, because they are the same: to protect plants from attacks by herbivores, to offer climbing plants a suspension system and to recover water from the atmosphere that condenses on their tip, a vital function in arid climates.
“Natural selection”
The study published in ScienceFor its part, it takes the reader on a journey through the evolutionary adventure of stingers. To locate the gene or genes involved in their formation, the team led by Zachary Lippman of the Cold Spring Harbor Laboratory (New York State) made the DNA of the plants of the genus speak. solarium (eggplants, tomatoes, potatoes, etc.).
The authors have thus discovered a new member of a family already known in flowering plants: the genes RECORDwhich ensure the last step in the production of a plant hormone, cytokinin. The mutation of this new gene, called boneless EITHER pl (“stingless”), has historically caused stinging loss in at least sixteen species of eggplant or related wild plants; losses that occurred independently, because they were not inherited from a common ancestor. “In some cases, the loss of spines appears to have occurred through a process of natural selection; in others, it is man who has selected spineless varieties, giving rise to domestic species such as the eggplant.explains in Science Elizabeth Kellogg, Harvard University.
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