Grass-dicot intercropping system for improved iron nutrition in crops

Overview

Iron (Fe) deficiency is a major agricultural challenge, particularly in calcareous and high-pH soils where most iron exists in insoluble forms. This solution proposes an intercropping strategy pairing grass species with dicot crops to naturally improve iron nutrition without relying on chemical fertilizers. Grasses secrete mugineic acid family phytosiderophores (MAs) from their roots, which chelate insoluble Fe(III) in the soil and facilitate iron uptake. While dicots cannot produce MAs, they benefit from the grass-derived chelators when grown together. This approach addresses Fe-deficient chlorosis, enhances photosynthesis, and improves overall plant health and yields in iron-limited environments.

Technical specifications

Key features:

• Leverages natural MAs secretion from grass roots to solubilize and mobilize iron in alkaline soils
• Utilizes transgenic approaches to enhance MAs efflux transporters (e.g., TOM1 overexpression in rice) for increased iron acquisition
• Employs barley NA synthase (HvNAS1) overexpression in dicots such as soybean and sweet potato to boost nicotianamine production, improving both iron and zinc concentrations
• Explores genetic diversity in Ae. tauschii (donor of the D genome to bread wheat) to identify accessions producing diverse MAs for breeding wheat varieties with enhanced iron uptake
• Investigates synergistic effects of intercropping wheat with rhizobium-infected soybeans for improved iron nutrition through symbiotic nitrogen fixation combined with MAs-mediated iron solubilization
• Validates the use of synthetic MAs analogs, such as proline-2′-DMA (PDMA), effective in both grasses and dicots

Technology readiness level

The underlying science has been validated through laboratory and greenhouse studies demonstrating improved iron nutrition in intercropped Erianthus with rice, as well as transgenic rice, soybean, and sweet potato lines with enhanced tolerance to iron deficiency. Future validation includes screening approximately 500 Ae. tauschii accessions for diverse MAs production and iron deficiency tolerance, followed by hydroponic and soil culture trials with wheat-soybean intercropping systems, ultimately scaling to field trials. The technology is at an early-to-mid stage of development, with breeding strategies and field validation ongoing.