Enhancing Nitrogen-Fixing Symbiosis in Crops using Rhizobia Bacterial Effectors

Nitrogen (N) is vital for plants.

However, its poor availability in soils has led to the widespread use of N fertilizers resulting in environmental problems like greenhouse gas emissions and water pollution.

Legumes offer a sustainable alternative to N fertilizers by forming symbiotic relationships with N-fixing bacteria, known as rhizobia.

Many rhizobia possess a Type III Secretion System (T3SS), to deliver effector proteins into host plants to facilitate colonization and N-fixing symbiosis. Some T3SS effectors activate host plant symbiotic signaling, while others suppress plant defense responses.

Furthermore, plant genotypes with specific Resistance (R) Proteins can detect rhizobial effectors, triggering immunity, and limiting colonization.

Although T3SS effector-dependent nodulation holds potential for enhancing N-fixing interactions in agricultural settings, research remains limited. Nodulation outer protein I (NopI) from rhizobia Sinorhizobium fredii HH103 enhances symbiosis in commercial soybean.

However, there are gaps in our knowledge regarding NopI function, interactions with plant targets, and recognition by R proteins.

In this MSCA fellowship, I will address these gaps using interdisciplinary approaches: Genome-wide association Studies, interactomics, and NopI structural determination.

In addition, I will explore the custom engineering of rhizobial T3SS effectors for modifying symbiosis, an innovative and timely strategy for improving host-rhizobia compatibility.

The host lab will provide a unique opportunity for me to expand my knowledge into the “bacterial side” of the legume-rhizobia interaction while sharing my expertise in the “plant side”.

I will have valuable networking opportunities and cutting-edge training in protein biochemistry and structural analysis, providing me with an interdisciplinary skills base to lead my own future research group focused on plant-symbiotic interactions and their practical applications in crop improvement.