Functional and Molecular Insights into Plant Interactions with Symbionts and Pathogens

This study addresses several critical factors involved in the establishment of plant-microorganism interactions, with a particular focus on pathogen-host dynamics using Ustilago maydis and Zea mays as model organisms. By examining factors that come into play even before the direct interaction between the pathogen and host, the research done for this work demonstrated how the specific genetic makeup and identities of different plant cultivars and fungal strains significantly influence the infection process. The use of deletion strains allowed for a detailed exploration of the functions and roles of selected U. maydis protein effectors during infection, confirming the essential role of UMAG_10156 in full virulence and excluding an infection phenotype for others, such as UMAG_12021. Furthermore, UMAG_12021 was ruled out as an isochorismatase but was structurally characterized, and key aspects of its structure were compared with those of representative members of the isochorismatase-like family. This structural analysis provides valuable insights for future research aimed at determining the precise function of UMAG_12021, alongside the solved structures of three proteins from this protein family, which will aid in advancing functional studies. Additionally, this study underscores the importance of kiwellins (Kwls) and kiwellin-like proteins (KLPs) in symbiotic interactions, revealing the recognition of Sinorhizobium meliloti by Medicago truncatula KLPs, as well as the binding of Kwls and KLPs to Agrobacterium spp. pathogens. These findings open new avenues for exploring the roles of kiwellins in mediating plant-microorganism interactions within diverse environmental contexts. Furthermore, the investigation into kiwellins introduced a simple and efficient screening method for identifying their protein interactors, offering a scalable approach that can be applied to broader protein interaction studies across different protein families.