Subcellular distribution and speciation of iron and manganese in pollen grains

Manganese (Mn) and iron (Fe) are essential micronutrients for plants, playing critical roles even in reproductive organs of plants, such as the pollen-bearing anthers. Our team has developed single-cell ICP-MS and metal staining methods, which, along with other researchers' work, have demonstrated that the accumulation of Fe and Mn in flowers is genotype, age and growth condition-dependent. Pollen grains are the organs most strongly accumulating Mn that further increases with flower maturation. We have found that mutations in the NRAMP5 transporter, which mediates the efflux of Mn and Fe from the trans-Golgi network, cause defects in pollen transmission (unpublished data). What remains to be determined is the exact location and species of Mn and Fe before and during flower pollination. Our aim is to investigate the distribution and form of Fe and Mn in wild-type and Mn/Fe transporter mutant flowers of Arabidopsis thaliana plants at tissue and subcellular levels using µXRF and µXANES.