Methods and compositions for nucleic acid sequencing using photoswitchable labels

A kit comprising four types of nucleotides for sequencing by synthesis, wherein a first type of nucleotide is a labeled nucleotide conjugate comprising a first photoswitchable label, wherein the first photoswitchable label comprises a silicon rhodamine fluorescent moiety covalently bonded, optionally via a first linker, to a first photochromic moiety, a second type of nucleotide is a labeled nucleotide conjugate comprising a second photoswitchable label, wherein the second photoswitchable label comprises a coumarin fluorescent moiety covalently bonded, optionally via a second linker, to a second photochromic moiety, a third type of nucleotide comprises a label having an emission at substantially the same wavelength region as the first type of nucleotide or the second type of nucleotide, and a fourth type of nucleotide is unlabeled.