3.1 Analysis of INH protein evolution
To analyze the evolution of INH in green plants, the PpINH1 protein sequence was used to conduct a BLASTP search for similar proteins in the One Thousand Plant Transcriptomes database (E-value < 10-10). More than 2000 target sequences were identified in this initial step, and 100 green plant species were selected to examine INH evolution (Figure 1a ). INH was found only in the flowering plants, including conifers, monocots, and eudicots. To analyze the evolution of INH in more detail among angiosperms, we used BLASTP to query the Phytozome 12.1 database to define a smaller number of representative flowering plant species and then counted the number of INH genes in each one (Figure 1b ). It is interesting to note that no INHs were detected in Amborella trichopoda , which is the common ancestor of living angiosperms. Variations in the number of INH genes are also observed, presumably reflecting gene duplication and loss events that have occurred during speciation, and there is a clear difference between dicots and monocots (Figure 1b ). Analysis of INH genes at the nucleic acid level shows that the first of 4 conserved cysteine sites are encoded as “TGC” in all species. However, the other conserved cysteine codons are more heterogeneous (Figure 1c ).