Crop species and wild plants differ in their ecological roles and traits

Rubén Milla

This is a plain language summary of a Functional Ecology review article which can be found here.

The bulk of our food supply ultimately depends on a few species of agricultural plants: corn, wheat, legumes, fruit trees and vegetables, among others. In total, a few hundred species. But where do they come from and how did they become agricultural plants?

Scheme of a stand of crop plants that may serve multiple ecosystem services, including fostering yields through resource-use complementarity, storing more carbon in the soil through deep and diverse root systems, providing more nutritious and diverse grains, or relying more on mycorrhiza and less on synthetic fertilizers for their mineral nutrition (credit: Rubén Milla)

All of them come from a wild progenitor. For example, maize is descended from natural populations of the species Zea mays ssp. parviglumis (Balsas teosinte), which inhabits forest clearings and open sites in the Balsas River basin in central Mexico. During the evolution from wild plants to domesticated varieties, crops changed in several ways. For example, in maize mutations were selected that resulted in plants with strongly upright growth, little branching, and few, but large, ears. However, such radical changes in their way of life, i.e., transitioning from natural to agricultural habitats, must have had consequences on many other aspects of the biology of crops.

In this review, I tackled the changes in the ecological performance of crop plants associated with domestication. For example, we highlighted that the good digestibility of agricultural species—another trait that evolved under domestication—does not come for free. The selection of palatable agricultural plants made them more sensitive to pests, and therefore I had to defend them with phytosanitary products of high economic and environmental cost. Similarly, the increase in the yield of these plants has decreased their nutritional quality. For example, the seeds of grain legumes have lost much of the carotenoids—important precursors of vitamin A—which were present in the seeds of their wild progenitors. Other consequences of domestication include the evolution of large plants with large seeds and decreases in the performance of mycorrhiza—a symbiotic relationship between certain soil fungi and plant roots which provides mineral nutrients to plants. There are many other ecological processes for which we still largely ignore with regards to the consequences of domestication, including relationships with microbes, plant-plant interactions, trade-offs among traits, or the genetic basis of changes in ecological traits.

Understanding the full implications of domestication for the functioning of agricultural plants and fields is an area of intense research today, and one from which we can learn a from in order to move towards a more sustainable and productive agriculture.


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