Leaves were collected in 2017 from radish plants in fields in northern China with virus-like symptoms, and four infectious clones of turnip mosaic virus (TuMV) were generated from these samples (CN3:MH735111, CN7:MH735112, CN8:MH735113, and CN9:MH735114). The genomic sequences of these four isolates were determined and showed 90.53% - 99.96% nucleotide identity, and 97% - 99.94% amino acid identity. Among these four isolates, CN7, CN8, and CN9 were most closely related to Chinese isolate CCLB (KR153038), and CN3 was most closely related to Korean isolate HJY1 (KX674727). Phylogenetic analysis of TuMV genomic sequences showed that all four isolates clustered into the basal-BR group. Only four differential amino acids in the N-terminal half of the polyprotein (one in P1, two in HC-Pro, and one in CI) of three of these isolates were associated with varied symptom development in Nicotiana benthamiana. Although CN3 had the most divergent polyprotein sequence, the symptoms induced by CN3 and CN9 were the most similar among the four isolates. Residue V241 in P1, and HC-Pro residues G485 and S646 were unique to CN8, while CI residue E1459 was unique to CN7. In previous work we have found no association of HC-Pro differences between 20 Korean TuMV isolates and symptom severity. Chimeric constructs between stem necrosis-inducing isolate CN7 and mild isolate CN8 suggest that amino acids A241 in P1 and E1459 in CI are most likely required for induction of stem necrosis.