The root of the problem of perennials domestication: is selection for yield changing key root system traits required for ecological sustainability?

Abstract

Aims: During the process of domestication of herbaceous seed-producing perennial crops, selection for high yield induces a shift in the resource-use strategy from conservative to acquisitive. So far, studies on plant domestication has been focussed on the response of aerial productivity rather than in roots. Here we aimed to keep track of changes in root, in order to prevent the loss of root traits contributing to plant survival and longevity. Methods: Using the perennial forb Physaria as a model, we compared the root system and its capacity for acquisition and storage of high yield and stable yield selected plants and their wild counterpart. Results: High-yield accessions showed higher N acquisition rate and lower amount of reserves in roots than stable and wild accessions. Structural differences in root systems may be partially responsible for differences in acquisition rate and storage among accessions. Conclusions: High-yield plants maintained high acquisition rates and an acquisitive set of traits, but showed a lower investment in storage that might affect longevity and yield stability. Ideally, the root system ideotype of perennial crops for marginal lands should combine the storage capacity of wild plants (i.e., hierarchical allocation of TNC and N to roots) with the high acquisition capacity of high-yield accessions.