To assess the evolutionary relationship of nine NnTPS genes, a small evolutionary tree was constructed using the nine NnTPS genes to exam NnTPS gene structures which are typical imprints of evolution within some gene families. The length of gene introns was larger and genetic structures were more complicated in NNU_024672, NNU_020115, NNU_000253, and NNU_016432 than the other NnTPS genes (Figure 1). All NnTPS genes contain at least one intron in their CDSs: most of them have three introns, one (NNU_004429) has four introns and one (NNU_022788) has five introns. According to the previous reports (Nuruzzaman et al., 2010; Hu et al., 2016), the rate of intron gain is slower than that of intron loss after segmental duplication in rice. Thus, it can be concluded that NNU_022788 might be the most ancestral with the other NnTPS genes derived from it. Compared with similar CDS length (2535–2814 bp) among 9 NnTPS genes, their gene length is even more variable (3583–8291 bp).