provided are a eukaryotic expression system and its applications . the eukaryotic expression system has a recombinant plant cell . the recombinant plant cell includes a first vector and a second vector . the first vector expresses a fusion protein containing an asia tospoviral common epitope . the fusion protein containing asia tospoviral common epitope consists of an amino acid sequence as set forth in seq id no . 1 , and a predetermined protein fragment connecting to the asia tospoviral common epitope . the above eukaryotic expression system is useful for monitoring the interaction between proteins via use of a specific peptide to tag the predetermined protein and demonstrates high sensitivity and stability .