The present invention provides a method of identifying mRNA transcripts in the transcriptome of a cell comprising i) delivering into the cell a donor expression vector comprising nucleotides in a sequence encoding a trans-splicing barcode cassette, ii) exposing the cell to conditions such that the cell produces multiple copies of the trans-splicing barcode cassette encoded by the donor expression vector, which multiple copies of the trans-splicing barcode cassette each splice the barcode polynucleotide onto a mRNA transcript of the cell, thereby forming multiple mRNA transcripts of the cell, each spliced to the barcode polynucleotide; and iii) identifying the multiple mRNA transcripts that are spliced to the barcode polynucleotides, thereby identifying mRNA transcripts in the transcriptome of the cell.