Investigating the mechanistic underpinnings of silicon (Si) absorption in contrasting varieties of soybean (Glycine max L.)

Silicon (Si) is a highly beneficial mineral nutrient for some plants, conferring significant resilience against a wide range of environmental stresses, both abiotic (e.g., drought and salinity) and biotic (e.g., disease and herbivory). How plants absorb Si and utilize it to withstand such different stressors remains an active area of research. So is the question of what explains the vast differences in Si-uptake capabilities, both across and within plant species. In this project, we will explore the molecular, cellular, and physiological mechanisms underpinning Si absorption in two contrasting varieties of soybean (Glycine max L.): Hikmok (a high Si accumulator) and Majesta (a low Si accumulator). Preliminary findings have shown that Hikmok can accumulate twice the amount of Si (on a leaf dry-weight basis) compared to Majesta (and most other commercial varieties), and genome-wide association study (GWAS) analysis has linked this trait to a Si transporter-encoding gene. This project will entail multiple layers of investigation, including (i) a molecular-genetic characterization of the gene and transporter of interest, utilizing various techniques, including qPCR, immunohistochemistry, cloning, and heterologous expression systems; (ii) measuring Si uptake and tissue accumulation in planta; and (iii) investigating the relationship between Si absorption, stress resilience, plant performance, and yield (in the greenhouse). Advances here will provide much needed insight into Si-uptake mechanisms in dicots (which are relatively underexplored compared to monocots) and inform future breeding programs aimed at improving Si absorption and Si-derived stress resilience in crops.