The centrosome is a non-membrane bound cellular compartment consisting of two centrioles surrounded by a protein
coat termed the pericentriolar material (PCM). Centrioles generally remain physically associated together (a phenomenon
called centrosome cohesion), yet how this occurs in the absence of a bounding lipid membrane is unclear. One model
posits that pericentriolar fibres formed from rootletin protein directly link centrioles, yet little is known about the
structure, biophysical properties or assembly kinetics of such fibres. Here I combine live cell imaging of endogenously
tagged rootletin with cell fusion, and find previously unrecognised plasticity in centrosome cohesion. Rootletin forms
large, diffusionally stable, bifurcating fibres, which amass slowly on mature centrioles over many hours from anaphase.
Nascent centrioles (procentrioles) in contrast do not form roots, and must be licensed to do so through polo-like kinase 1
(PLK1) activity. Transient separation of roots accompanies centriolar repositioning during the interphase, suggesting that
centrioles organize as independent units, each containing discrete roots. Indeed, forced induction of duplicate centriole
pairs allows independent re-shuffling of individual centrioles between the pairs. Thus collectively, these findings suggest
that progressively nucleated polymers mediate the dynamic association of centrioles as either one or two interphase
centrosomes, with implications for the understanding of how non-membrane bound organelles self-organise.