Genetic tools for enhancing arbuscular mycorrhizal symbiosis in sorghum

Overview

This research program investigates the genetic basis of arbuscular mycorrhizal fungi (AMF) symbiosis in sorghum to support sustainable crop production. AMF form mutualistic partnerships with plant roots, extending hyphal networks that dramatically improve phosphorus (P) uptake from soil. Because phosphorus is sourced from non-renewable geological deposits and costs are expected to rise, reducing dependence on synthetic fertilizers is a critical agricultural challenge. Modern breeding has unintentionally weakened crops' ability to support AMF, making it essential to identify the genes that enable this beneficial symbiosis. By leveraging DMI1 mutant sorghum lines, this work aims to uncover the molecular mechanisms regulating AMF symbiosis and provide genetic targets for breeding programs.

Technical specifications

Research approach:

• Ten DMI1 mutants from Purdue's Sorghum Gene Discovery Platform will be examined by microscopy for their ability to host AMF
• AMF-resistant mutants will be backcrossed to wild-type BTx623 to generate a BC2S1 mapping population
• Plants will be grown in sterile greenhouse soil inoculated with AMF from INVAM
• Transcriptome profiling using RNA extracted from root samples at three developmental stages
• Differentially expressed genes will be analyzed using weighted gene co-expression network analysis to identify candidate genes regulating symbiosis

Key scientific foundation:

• Based on the Medicago truncatula DMI1 gene, which encodes a protein similar to prokaryotic cation channels essential for microbial symbioses
• Inspired by successful maize studies using Castor (DMI ortholog) mutants that identified QTL linked to host benefit from AMF
• Novel strategy of incorporating AMF-resistant controls to facilitate breeding crops that support AMF

Technology readiness level

This is an early-stage research program in the discovery and validation phase. The DMI1 sorghum mutants have already been obtained and the experimental design including microscopy screening, backcrossing, greenhouse trials, and transcriptome analysis is established. The work builds directly on validated methodology from maize studies, providing a strong proof-of-concept foundation. Upon completion, this research will deliver candidate genes and genetic markers that plant breeders can use to develop sorghum varieties with enhanced AMF symbiosis capability, ultimately reducing dependence on synthetic phosphorus fertilizers.