*5.4. Chromosomal Location and Synteny Analysis*

MapChart (version 2.32) was used to predict the distribution of OfXTH genes on chromosomes. Quick Run MCScanX Wrapper program in TBtools1.6 was used to assess gene duplication events of *OfXTHs*. The synonymous (Ka) and non-synonymous (Ks) substitution rate were calculated by the Simple Ka/Ks Calculator program of TBtools1.6. The divergence was calculated as follows: T = Ks/2λ, where <sup>λ</sup> = 1.5 × <sup>10</sup>−<sup>8</sup> s for dicots [38]. The selection mode was identified using Ka/Ks value (Ka/Ks ratio >1, <1 and =1 represented positive selection, negative selection, and neutral selection, respectively) [38].

#### *5.5. Analysis of Cis-Acting Regulatory Elements in Promoter*

The upstream sequences (2 kb) of the OfXTH-coding sequences were obtained from the genome database of *O. fragrans* [35]. PlantCARE (http://bioinformatics.psb.ugent.be/ webtools/plantcare/html/ (accessed on 17 March 2022)) was used to identify cis-acting regulatory elements in *OfXTH* genes promoter.
