*2.1. Identification of XTH Gene Family in O. fragrans*

Through the HMM search with the XTH protein domains (PF00722 and PF06955) and BLASTp with 33 AtXTH proteins, a total of 38 *OfXTH* genes were identified from the *O. fragrans* genome. Then, the characteristics of OfXTH proteins were investigated, including protein length, molecular weight (MW), and theoretical isoelectric point (pI), by the online software Expasy. The signal peptide (SP) and subcellular localization were predicted by the online program SignalP 4.1 Service and Plant-mPLoc. The results showed that the length of amino acids was between 234 and 355, and the molecular weight of the proteins was between 26.8 and 40.4 kD (Table 1), corresponding with the protein length. The theoretical isoelectric point varied from 4.83 to 9.47; this is possibly due to the different polarities of the amino acids. In addition, a total of 29 OfXTH proteins were predicted to contain a signal peptide, while the other nine proteins had no signal peptide. Additionally, the subcellular localization prediction revealed that 32 OfXTH proteins were located in the cell wall, and six proteins were predicted to locate in the cell wall or cytoplasm (Table 1).


**Table 1.** The characteristic of *OfXTH* genes in *O. fragrans*.

