The Technion researchers found how the fruit's defenses turn a seed predator into a quality spreader

This is the first documentation of a chemical system in fruits that promotes seed dispersal by mammals

bitter seeds
Anyone who stops for a break on a trip in the Negev knows the nice rodent that appears to collect food scraps in the field. The golden thorn, so named because of the coarse hairs on its fur, is a golden thorn,
He eats everything and in the seasons of "abundance" he will prefer fruits and especially the sweet fruits of the rakfatan, one of the common plants in the Negev wadis, a large green bush with thin and long branches and small leaves that fall during dry periods.

In the spring, the hollyhock blooms with tiny yellow flowers. The Bedouins usually collect the flowers and season and color soup or rice with them and the result is similar to seasoning with turmeric. After the flowers come the fruits, the cypress is covered with clusters of white and sweet berries and of course the thorns harvest the clusters and eat the fruits with great gusto.

The sweet white fruits contain black seeds and once again the Bedouin "know-it-alls" prepare hallucinogenic "medicines" from the seeds. The taste of the seeds is similar to the taste of spicy mustard, a taste that is not liked by the thorns and it turns out that this is the "patent" that the raccoon developed to spread its seeds.

Plants have a problem. They develop sources of food and attraction for animals that will spread their seeds, flowers full of nectar attract insects that pollinate them, sweet or nutritious fruits are eaten and the eaters spread the seeds in the fruits, there are cases when the seeds pass through the digestive systems without damage and are excreted in a pile of secretions that serve as food soil.

There are seeds that "must" pass through the hot and acidic environment of a digestive system in order for them to germinate, the problem is attracting distributors who will not harm the seeds, to solve the problem to cover them and there are bitter seeds.

Michal Samoni publishes incurrent-biology Follow-up results (video) after the thistles that harvest the clusters of sedum, move away from the bush and eat the fruits, but it turns out that the thistles do not swallow the bitter seeds but spit them out.
It is possible that the act of spitting is learned after "cracking" a sperm causes what Simoni defines as a "mustard bomb". Breaking the seed causes a repulsive taste to spread and the rodent learns to eat the sweet fruit and spit out the seed,

The fruits of the sardines are also a source of attraction for nightingales and other birds, therefore we will clarify that rodents or mammals chew their food and in the above case the chewing breaks the seeds, which causes the spread of the repulsive taste, birds swallow food and thus the sweet fruit is swallowed whole without the seeds causing rejection. It turns out that there is a mechanism which ensures the distribution of the seeds by what is defined as "secondary digestion", secondary metabolites. He who damages the seeds learns not to touch the fruit or alternately like the thorn learns to eat the fruit without the seeds. Those who swallow the seeds whole do not feel the repulsive taste. Now it is worth checking if the birds excrete essential seeds in their defecation, because if not, it is clear that the preferred distributor for the hens is the thorn.

Note. For some reason in the publications in Lez there is a confusion between the sedum Ochradenus baccatus which is a desert plant and as such inhabits the habitat of the spikes and the scented sedum Reseda odorata that grows in Mediterranean areas and the sedums do not encounter it. odd.

Technion announcement

The Technion researchers from the Faculty of Biology found how protective substances in the fruit turn a seed-crazy rodent into a spreader. The researchers found in the fruits of the desert plant, the desert gorse, a chemical system that encourages the distribution of seeds.

In this system, stable and non-toxic substances, called glucosinolates, are found only in the surface of the fruit and break down into toxic decomposition products in case of mechanical damage to the seed where the myrosinase enzyme responsible for their decomposition is found. It appears that the glucosinolate and myrosinase compartmentalization in the fruits of the gorse affect the interactions between the gorse and rodents known as seed predators. One of the tested rodents, the common spiny, was even found to be a high-quality seed spreader of the raccoon.

This is, in fact, the first documentation of a chemical system in fruits that promotes seed dispersal by mammals.

The direct deterrence theory states that defensive substances (secondary metabolites) in ripe fruit will deter seed predators, but will have little or no effect on seed dispersers. Indeed, a number of studies have shown that birds, seed dispersers, feed on fruits with protective substances while rodents shy away from them. However, this mechanism has only been shown based on differences at the class level, for example in vanilloid receptors that are present in mammals but absent in birds.

"Here we present the findings of physiological and behavioral experiments showing the use of mustard oil bomb-type protective agents that encourage seed dispersal in a broad spectrum, regardless of class (for example: mammals vs. birds), in the fruits of the desert mulberry, with the aim of forcing a behavioral change in the ecological timeline, which encourages seed predators to drive as distributors". Says the researcher, Michal Semoni-Blank, who studied the subject under the guidance of professors Zeev Arad from the Technion and Ado Itzhaki from the University of Haifa. "This change is achieved through a unique compartmentalization of the mustard oil bomb, which creates an activation of the system only when the animal consumes both seeds and float. This is how 'Dirbon' was created for distribution, leading to the first evidence in the world of a rodent spreading seeds by spitting. The research findings show the power of protective substances in changing animal-plant relations from predator-prey relations to mutual relations, and provide reinforcement for the direct warning theory also at the intra-sexual level, in addition to the inter-sexual level.