*5.8. Real-Time Quantitative PCR*

PrimeScript RT Reagent Kit (Takara, Dalian, China) was used for first-strand cDNA synthesis following the manufacturer's instructions. LightCycler480II Real-Time PCR System was used for qRT-PCR analysis. The reaction mixture (10 μL total volume) consisted of 5 μL SYBR Premix Ex Taq (Takara, Dalian, China), 20 ng cDNA template, forward and reverse primers (10 microns/L) of 0.4 μL, was and filled with ddH2O to 10 μL. Three biological replications were performed for each treatment. The relative expression of the target gene was calculated using the 2−ΔΔCT method. OfACT was used as a reference gene [39]. Primers of *OfXTH* genes used in RT-qPCR are shown in Table S3.

**Supplementary Materials:** The following supporting information can be downloaded at: https:// www.mdpi.com/article/10.3390/plants11081015/s1, Figure S1: Flower bud phenotype of *O. fragrans* at different stages; Figure S2: Flower bud phenotype under temperature treatment; Table S1: Chromosome location of OfXTH genes; Table S2: DEGs of 2d-19 °C vs 2d-23 °C; Table S3: Primers of OfXTH genes used in RT-qPCR; Table S4: The FPKM value of OfXTH genes in temperature treatment transcriptome; Table S5: The RT-qPCR raw data of OfXTH genes at different

flowering stages; Table S6: The RT-qPCR raw data of five differential expressed OfXTH genes treated at 19 ◦C and 23 ◦C.

**Author Contributions:** Conceptualization, S.Z.; methodology, Y.M.; software, Y.Y.; validation, Q.F. and Y.W.; investigation, Y.Y.; data curation, Y.Y.; writing—original draft preparation, Y.Y.; writing—review and editing, Y.M., S.Z. and B.D.; visualization, Y.Y.; supervision, B.D.; project administration, H.Z. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was funded by the National Natural Science Foundation of China (Grant No. 32072615 and 31902057), Zhejiang Provincial Natural Science Foundation of China (Grant No. LQ19C160012), and the key research and development program of Zhejiang Province (2019C02036).

**Data Availability Statement:** Data are contained within the article.

**Conflicts of Interest:** The authors declare no conflict of interest.
