Abstract

Background and aimsSoil microorganisms play a pivotal role in modulating plant nutrient uptake, yet the influence of soil yeasts on nitrate transporter dynamics remains largely unexplored. This study examines the effects of two rhizosphere yeasts-Solicoccozyma terrea (a yeast strain with ACC-deaminase activity) and Metschnikowia sp. (indole-3-acetic acid producer)-on the expression and tissue localization of three nitrate transporters (NRT1.2, NRT2.1, and NRT2.3) in tomato (Solanum lycopersicum) roots.MethodsPlant roots were exposed to both, individually or in combination, yeast strains under controlled conditions. Gene expression analysis via RT-qPCR was performed every two days after exposure, and after 20 days, stem samples were collected to determine nitrate content in the xylem sap. In a second experiment, plants were transformed to express the nitrate transporters of interest fused to NeonGreen. After 20 days of exposure to the yeast strains, root samples were collected and analyzed by confocal microscopy.ResultsThe expression of the high-affinity nitrate transporters NRT2.1 and NRT2.3 was upregulated by S. terrea, while Metschnikowia sp. induced transient expression of the dual-affinity LeNRT1.2. Confocal imaging showed yeast-specific shifts in transporter localization, with S. terrea enhancing vascular bundle accumulation and Metschnikowia sp. promoting epidermal presence of NRT2.3.ConclusionsThese findings suggest that soil yeasts can modulate nitrate acquisition pathways through distinct biochemical signaling, offering new perspectives on microbiome-driven strategies to improve nitrogen use efficiency in horticultural systems.