Summary model illustrating the effect of blue light on FIT NB formation and iron uptake, suggesting that FIT NBs are related to transcriptional and posttranscriptional regulation in speckles and that blue light has a promoting effect on iron uptake. FIT accumulates in FIT NBs upon induction with blue light. FIT NBs are reversible, dynamic, and of circular shape and may undergo LLPS. FIT homodimers and FIT–bHLH039 heterodimers are present in FIT NBs. FIT–bHLH039 is an active TF complex for upregulating the expression of iron acquisition genes in roots (Gratz et al., 2019). Hence, FIT NBs are subnuclear sites related to transcriptional regulation and because of their colocalization with speckle components, also to speckles. Blue light enhances root iron reductase activity and gene expression of FRO2 and IRT1, all of which are downstream of FIT–bHLH039. In summary, FIT NBs are blue light-inducible subnuclear sites where active TF complexes of FIT and bHLH039 accumulate, linking transcriptional and posttranscriptional regulation in speckles with a promoting blue light effect on iron uptake. The figure has been created with the help of https://BioRender.com.