Assistant Professor East Stroudsburg University East Stroudsburg, Pennsylvania
Body of Abstract: In many soils, limited plant-accessible phosphate (Pi) levels constrain plant growth. To overcome this, many plants establish symbiotic associations with arbuscular mycorrhizal (AM) fungi, thereby obtaining Pi from the fungal symbiont. This relationship alters root cell metabolism and physiology, particularly the pathways of Pi entry into the roots. The impact of AM symbiosis on the Pi content and response dynamics of root cells, however, remains to be fully understood.
Utilizing fluorescence resonance energy transfer (FRET)-based Pi biosensors, we examined the cytosolic and plastidic Pi levels within intact mycorrhizal roots of Brachypodium distachyon. We discovered that colonized cells possess a higher cytosolic Pi content compared to non-colonized cortical and epidermal cells. Cells at the infection front demonstrated the highest plastidic Pi content. Application of Pi to the mycorrhizal root system resulted in transient cytosolic Pi alterations that varied based on cell type and arbuscule status. Further, applying Pi to extraradical hyphae induced measurable cytosolic Pi changes in colonized cells, noticeable 18 hours after application. These findings reveal how AM fungal colonization affects the intracellular Pi homeostasis of host root cells, emphasizing the diversity in Pi content and Pi response dynamics.