  Tunable symmetry breaking plays a crucial role for the manipulation of
topological phases of quantum matter. Here, through combined high-pressure
magneto-transport measurements, Raman spectroscopy, and X-ray diffraction, we
demonstrate a pressure-induced topological phase transition in nodal-line
semimetal ZrSiS. Symmetry analysis and first-principles calculations suggest
that this pressure-induced topological phase transition may be attributed to
weak lattice distortions by non-hydrostatic compression, which breaks some
crystal symmetries, such as the mirror and inversion symmetries. This finding
provides some experimental evidence for crystal symmetry protection for the
topological semimetal state, which is at the heart of topological relativistic
fermion physics.
