It's been known for many decades that the nuclei of animal cells are constantly in motion within the cell. Less well known, and less well studied, is the fact that the nuclei of plant cells are also often in constant motion.

While textbook figures imply nuclei as resting spheres at the center of idealized cells, this picture fits few real situations. Plant nuclei come in many shapes and sizes, and can be actively transported within the cell. In several contexts, this nuclear movement is tightly coupled to a developmental program, the response to an abiotic signal, or a cellular reprogramming during either mutualistic or parasitic plant–microbe interactions.

Source :Frontiers in Plant Science, 5: 129

The reasons behind the movements, and their underlying biomechanics, are for the most part still a mystery.

While many such phenomena have been observed and carefully described, the underlying molecular mechanism and the functional significance of the nuclear movement are typically unknown.

[Source as above]

It's known that the nuclear movements can be enhanced or provoked by mechanical stimuli, light and chemical changes.