Cracking the Manganese Code of Plant Reproduction

Manganese (Mn) is critical for pollen function, yet its subcellular localisation, speciation, and mobilisation during germination are unknown. In Arabidopsis thaliana, we identified two Mn hotspots in dry pollen by µXRF (ID21): 0.7–2 µm crystal-like structures and eye-glass shaped assemblies around sperm cells. Loss of Mn transporters abolishes these hotspots and reduces seed set. Hydration experiments suggest that Mn undergoes redistribution to support fertilisation. Using kinetic nano-XRF, XANES, and quasi-correlative nanoXRF and transmission electron microscopy, we will identify the organelles that host Mn, the Mn ligands, how Mn is remobilised during germination and how anther tissues deliver Mn to pollen, revealing mechanisms critical for reproductive success.