Genetic improvement of legume roots for adaption to acid soils

Acid soils occupy approximately 50% of potentially arable lands. Improving crop productivity in acid soils, therefore, will be crucial for ensuring food security and agricultural sustainability. High soil acidity often coexists with phosphorus (P) deficiency and aluminum (Al) toxicity, a combination that severely impedes crop growth and yield across wide areas. As roots explore soil for the nutrients and water required for plant growth and development, they also sense and respond to below-ground stresses. Within the terres-trial context of widespread P deficiency and Al toxicity pressures, plants, particularly roots, have evolved a variety of mechanisms for adapting to these stresses. As legumes, soybean (Glycine max) plants may acquire nitrogen (N) through symbiotic nitrogen fixation (SNF), an adaptation that can be useful for mit-igating excessive N fertilizer use, either directly as leguminous crop participants in rotation and inter-cropping systems, or secondarily as green manure cover crops. In this review, we investigate legumes, especially soybean, for recent advances in our understanding of root-based mechanisms linked with root architecture modification, exudation and symbiosis, together with associated genetic and molecular strategies in adaptation to individual and/or interacting P and Al conditions in acid soils. We propose that breeding legume cultivars with superior nutrient efficiency and/or Al tolerance traits through genetic selection might become a potentially powerful strategy for producing crop varieties capable of maintain-ing or improving yields in more stressful soil conditions subjected to increasingly challenging environ-mental conditions.& COPY; 2023 Crop Science Society of China and Institute of Crop Science, CAAS. Publishing services by Elsevier B.V. on behalf of KeAi Communications Co. Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Automated summary

Acid soils cover approximately 50% of arable lands, and improving crop productivity in these soils is crucial for food security and agricultural sustainability. The combination of high soil acidity, phosphorus deficiency, and aluminum toxicity severely affects crop growth and yield. Legumes, such as soybeans, have evolved mechanisms to adapt to these stresses, including root architecture modification, exudation, and symbiosis. Breeding legume cultivars with superior nutrient efficiency and aluminum tolerance traits through genetic selection could be a powerful strategy for maintaining or improving yields in challenging soil conditions.