Isolation of Microbiome-Mediated Bacteria in the Rescue of Vitamin B6 Homeostasis in Arabidopsis thaliana
Sydney Kenber, Jakob Napitan
Department of Biology
Faculty Supervisor: Zheng-Hui He
Vitamin B6 (pyridoxal phosphate) is an essential metabolic cofactor involved in amino acid metabolism and protection against environmental stress, including ultraviolet-B (UV-B) light while soil microbial communities are fundamental regulators in plant nutrient homeostasis, stress tolerance, and development. The rus1 mutant of Arabidopsis thaliana, which is a knockout mutation of the rus1 gene that affects VitB6 homeostasis and is sensitive to UV-B light, which in turn leads to severe developmental arrest. Our previous research discovered that this phenotype can be rescued when plants are grown in non-sterile soil, suggesting that soil microbiota can metabolically compensate for the impaired vitamin B6 salvage pathway. This study aims to isolate and identify bacterial strains capable of rescuing the rus1 phenotype, giving us a clearer idea of how microbial communities contribute to nutrient homeostasis and stress mitigation in plants. Bacterial isolates are obtained from a soil slurry, then serially diluted and individually inoculated onto sterile growth media containing rus1 mutants and wild-type (WT) controls. Rescue will be assessed through measurements of aerial biomass, chlorophyll concentration, developmental progression, and seed production. To identify microbial contributors, 16S rRNA gene sequencing will be performed on isolates to determine their taxonomic identity. We hypothesize that soil microbes restore rus1 viability through metabolic complementation, potentially by synthesizing vitamin B6 or modulation of associated stress response pathways. By integrating phenotypic screening with molecular identification, this project works to advance our understanding of microbiome-mediated nutrient homeostasis. More broadly, it contributes to the emerging field of plant-microbe metabolic communication and could lead to strategies for microbial-assisted crop fortification under increasing climate stressors.