Plant domestication is a dynamic and ongoing process that has been largely studied by Archeology and Genetics, whereas the ecological aspects have been often overlooked. However, filling this gap is very important not only to better understand how plant domestication progressed but also to identify its evolution and future consequences. Archeological and genetic evidences highlighted that domesticated plants come from a phylogenetically diverse assemblage of wild ancestors (i.e. wild relatives) by artificial selection for different traits. Specifically, plant domestication is considered the result of a convergent evolution, which led different species to acquire a set of phenotypic traits (i.e. domestication syndrome). Nevertheless, also natural selection caused by the cultivation conditions (i.e. resources availability and disturbance intensity) can be considered a driver of crop evolution. Human selection based on traits of agronomical interest could have led to an indirect selection for other traits resulting from biophysical or eco-physiological constraints caused by agricultural practices. This could have produced shift in functional trait syndrome leading to hypothesize that domestication syndrome does not follow a unique model. However, redefine a new domestication syndrome scheme requires to identify traits not directly selected by artificial selection so that eco-physiological and biophysical constraints can be revealed. Accordingly, the proposed research aims to contribute redefining a new domestication syndrome scheme by using plant traits related to biomass allocation patterns (i.e. dry mass distribution through different plant organs). These patterns have a high responsiveness to abiotic factors and allow to understand the performance of plants, which experience different environmental conditions. Thus, the analysis of these patterns by using whole-plant traits is a valuable test-bed to analyze functional changes during crop domestication.
The innovative aspect of the proposed research consists in applying a strictly eco-physiological topic such as how biomass allocation patterns vary in response to water and nutrient limitations to a wider and multidisciplinary theme that is plant domestication process. Although there is a growing consensus on considering that the ecological trait-based approach has a good potential to address several unsolved questions on plant domestication, there are still lacks of data about the matter. In this context, the research aims to contribute filling the gap. The methodological set up to grow crops and their wild relatives in contrasting water and nutrient conditions reflects the environmental heterogeneity inherent to both natural and agricultural environment. As cultivation usually occurs under a higher water and nutrient supply rates, it is feasible that domestication caused a shift from resource-conservation towards resource-acquisition traits [1]. Up to date a few of these shifts have been investigated and most remain understudied. The rationale of the study will allow to test how environmental limitations affected domestication syndrome as well as to predict how and why changes in functional profile of crops occurred over the course of plant domestication, particularly in response to natural selection under cultivation. Results from this study by exploring possible changes in plant strategies during domestication, could significantly contribute to expand knowledge on plant domestication syndrome.
Another novel aspect of this research concerns the choice to focus, between the possible different plant traits, on those related to biomass allocation. Up to date such traits have been poorly explored as domestication syndrome was mostly described by modifications of reproductive organs [2]. As far as we know, a few studies have investigated how domestication changed biomass allocation patterns between crops and their wild relatives [2, 3] whereas how these patterns change across experimental treatments reflecting variations in water and nutrient conditions is still scarcely explored [4]. Data from this type of studies have the potential to test the plastic response to environmental changes after domestication that is crucial to evaluate how cultivated plants are adapted to novel environments.
Overall, the proposed research could substantially contribute to detect shifts in plant strategies and then to expand understanding on domestication syndrome by identifying new phenotypic traits involved and by evaluating the role of the domesticated phenotypes in altering ecological process. Moreover, as it is estimated that 2500 plant species have undergone domestication worldwide, with over 160 families contributing one or more crop species [5], the obtained results can have a higher applicative potential in the agroecology context. In fact, they could be used to operate an ecological-based selection and domestication of wild species suitable for a new generation of domesticated crops.
[1] Milla et al. 2015 Trends Ecol Evol 30: 463-469
[2] Roucou et al. 2018 J Appl Ecol 55: 25-37
[3] Wacker et al. 2002, Plant Biol. 4: 258-265
[4] Milla et al. 2018, Envion Exp Bot 145: 54-63
[5] Meyer et al. 2012 New Phytol 196: 29-48