The key for domestication. Humans’ capability or plant’s domesticability?

Oryginal date of publishing January 15/2025, By Marta Koblańska, Photo: Pixabay

Just 15 edible plants provide us 90 percent of calories while a few hundred have been finally domesticated of the thousands of them. Why? The answer might be eligibility for domestication or humans’ limited ability.

As state scientists, University of Southampton, UK in the newly published article in ,,Trends in Ecology and Evolution”, crop domestication arises from a coevolutionary process between plants and humans, resulting in predictable and improved resources for humans. At the beginning of their existence, humans consumed trees’ leaves and flash abandoned by other predators. Hunting and cultivation of plants which supported first human groups with energy came later. There are theories that meat and particularly cooked meat enabled so spectacular brain development but, on the other hand, plants are those who contributed the most to, lets say, higher culture. Agriculture though became a strong base for further civilization both because of surplus possible for distribution or its storage. Anyway the success of domestication of plants drove us to over 8 billion people living on the Earth in various environment and conditions.

But, someone may ask, why we succeeded with only several domesticated plants delivering us often majority of energy we need to live, work, study or produce and distribute our ideas or discoveries? Some plants due to their genetic variants may be easier to edit and thus adapt to the environment offered by humans. Some are different and not eligible for domestication. This is why there is a difference between our capability to genetically adopt plant for our purposes and needed quantities as well as the plant capacity to adapt to new conditions.

British scientists asked a question: ,,are there genomic and phenotypic features that facilitated or constrained the domestication of certain wild species under human management or cultivation? And they further state this knowledge would have consequences for understanding how future food security can be ensured. Why? Because hundreds of wild plants were collected and cultivated during the Neolithic and then abandoned as efficient food sources. But at that time the number of humans had been much lower than today.

What makes plants possible to cultivate?

The answer is simple. Their traits and more precisely the traits of their progenitors what stipulates a specific variant of genetic code which either enables adaptation to new requirements or makes it more difficult or impossible. The scientists admit, if crop progenitors possess traits that increase their domesticability, then domesticated species are a biased sample not representative of natural selection in the wild. If so, domestication could instead be a model for understanding the rapid evolution of highly evolvable species.

The trait which is particularly desired from humans point of view is plasticity of a plant phenotype. This phenotype may be induced by climate change and/or human management. The phenotype expresses plant outfit while, as the scientists underline, plasticity is an adaptive mechanism that can result in multiple phenotypes from a single genotype. It is driven by transcriptomic changes in response to environment. In other words this is a rapid way of introducing new phenotypes into the population with pre-existing genetic variation. Of course the key is genotype ( hidden resources of species) which constitutes in the process of propagating and needs to its growth and expression certain conditions along with water and nutrients. Scientists admit that genotypes with high plasticity may be able to acquire resources quicker and increase growth under optimal conditions. Roots and leaves are
particularly sensitive to growing conditions and root traits are known to be highly plastic.

Plasticity could therefore ‘push’ crop progenitors in the right direction when brought into cultivation, accelerating adaptation to the cultivated environment and producing traits that humans would benefit from, as opposed to waiting for the relevant genetic mutation.

says Anne J. Romero, the lead author of the study.

But, certainly, specific mutations may also make the process of domestication easier and more efficient. But the process remains for now impossible to control if occurs in nature. However, despite mutations are random process, some of them may result with benefits. But, in the other hand limits the most human ability to assimilate the wild. For example, as British scientists hold, the number of loci responsible for selected traits, their dominance/recessiveness, and their arrangement in the genome (i.e., linkage), determines how fast species can adapt/evolve under selection. These together could have favoured some species over others. Selection from standing variation can fix small numbers of alleles with large effects faster than a large number of alleles with small effects. To be clear a loci is, in some sense, a collection of spaces with, lets say the same properties. The more of them with beneficial bodies, the better effect might be. This effect for plants may be for instance more and bigger seeds, size or response to light availability. In contrary, loci with dysfunctional properties – the final effect becomes worse. And usually the level of difficulty along with the success in domestication comes from progenitors genome traits.

The scientists’ one of the most important conclusion is that crop progenitors may also be more resilient to disturbance. Defoliation of crop progenitors led to a 31 percent decrease in tillering and seed production, but a 61 percent reduction in never-domesticated relatives.

The author’s note: The post has been first published on January 15/2025 with the number 173. Due to technical issues the post number had to be changed for 224, however the oryginal date of publication has been sustained.