Root traits differ between wet- and dry-adapted sets of faba bean accessions selected by FIGS

Summary

Grain legumes, such as faba bean (Vicia faba L.), are important sources of protein, particularly for people in developing countries where climate change is expected to result in higher temperatures and changing precipitation patterns. Among grain legumes, faba bean is thought to be relatively sensitive to drought. Faba beans are important legumes in the crop rotations of organic farming. Deeper roots and larger root biomass have been shown to be important contributors to crop performance under drought conditions. Thus root traits could be used as the selection criteria for drought adaptation. During 2010–2011, two sets of faba bean accessions, from ‘wet’ and ‘dry’ regions, each containing 201 accessions, were chosen using the Focused Identification of Germplasm Strategy (FIGS). FIGS uses the environmental data (geographic and agro-climatic information) associated with the collection sites of plant genetic resources to identify sets of accessions ‘most likely’ and, in this case,‘least likely’ to express the trait of interest. The two sets were screened for a variety of morpho-physiological leaf traits related to drought adaptation. The results showed that FIGS successfully differentiated between material selected according to collection site moisture availability. From these results, it was hypothesized that root traits of the two FIGS sets would reflect their different geographic origins. Hence, root traits of six representative accessions from each set (chosen by principal component analysis) were evaluated under well watered conditions and then, under water deficit. Under well watered conditions, the ‘dry’ set had significantly higher root biomass than the ‘wet’ set, but no differences for root length and gas exchange traits. When the plants were exposed to water deficit, root length, root, and shoot biomass decreased significantly more in the ‘wet’ set than in the ‘dry’ one. The ‘dry’ set showed higher gas exchange than the ‘wet’ set under water deficit. These results, together with those on leaf traits, confirm the ability of the FIGS to identify germplasm for breeding for drought resistance in faba bean, and this may be extended to other crops and to other traits related to abiotic stresses and adaptation to climate change.