*2.3. Gene Family Identification*

Yang et al. identified 38 *OfXTH* genes belonging to the four main phylogenetic groups in *Osmanthus fragrans*. The gene structure, chromosomal location, synteny relationship and cis-acting elements and expression patterns were analyzed on a genome-wide scale. The expression patterns showed that most *OfXTHs* were closely associated with the floweropening period of *O. fragrans*, and five of them were involved in the regulation of flower opening by responding to ambient temperature changes [8]. Cao et al. identified twentynine *NnDofs* in lotuses, of which the physicochemical properties vary; however, all of which contain conserved zinc finger structures. A promoter analysis, RNA-seq atlas and qRT-PCR were performed to demonstrate the potential function of *NnDofs* in the salt tolerance of lotuses [9]. Gu et al. identified 21 *LiNAC* genes from the transcriptome data in *Lagerstroemia indica*, and the physicochemical characteristics of amino acids, their subcellular localization, transmembrane structure, GO and KEGG enrichment, and expression patterns were examined. A further qRT-PCR indicated that these *LiNAC* genes may be involved in the regulation of weeping traits in *L. indica* [10]. Ma et al. identified 16 *MsHSF* genes in *Medicago sativa*, and the physicochemical properties, subcellular localization, synteny analysis, GO annotation and enrichment, and the protein interaction networks of amino acids were also examined. Similarly, the RNA-Seq results found that the *MsHSF* gene family plays a key role in abiotic stress [11]. Guo et al. performed a phylogenetic analysis of 120 AP2/ERF genes in the *Rhododendron simsii* genome; cis-acting elements involving plant growth regulators, the response to abiotic stress and MYB binding sites were detected in the upstream sequences of *RsAP2* genes. In addition, twenty *RsAP2* genes were selected for a qRT-PCR, and the results showed that most of the *RsAP2* genes responded to these abiotic stresses [12]. Liu et al. analyzed 204 *HhMYB* family members in *Hibiscus hamabo* using RNA-seq and a qRT-PCR, and found that *HhMYB* was involved in plant responses to salt and drought stress to varying degrees [13]. Song et al. identified and analyzed 25 *SWEET* genes in *Rosa chinensis* 'Old Blush', and through a transcriptome analysis, *SWEET2a* and *SWEET10c* were found to be candidate genes involved in the rose's ability to tolerate cold conditions [14].
