**5. Conclusions**

In this study, we identified 91 PODs from the cassava genome and studied their basic classification, protein motif, gene structure, chromosomal distribution, and duplication pattern. Comprehensive transcriptional level analyses revealed the involvement of MePODs in biotic and abiotic stress responses, hormone responses, and storage root deterioration. Several *MePOD* genes (*MePOD-13, -17, -85,* and *-86*) were found to be transcriptionally upregulated after multiple different treatments, suggesting that these genes are good candidates to target for cassava improvement. These findings increase our understanding of POD-mediated stress and hormone responses and storage root deterioration in cassava, laying a foundation for the genetic improvement of cassava.

**Supplementary Materials:** Supplementary materials can be found at http://www.mdpi.com/1422-0067/20/11/2730/ s1. Table S1. Characteristics of PODs in cassava. Table S2. The Ka/Ks ratios of duplicated *POD* genes in cassava. Table S3. The expression profiles (log2-based values) of the cassava *POD* genes in different tissues. Table S4. The expression profiles (log2-based fold changes) of the cassava *POD* genes after drought treatment. Table S5. The expression profiles (log2-based fold changes) of the cassava *POD* genes after harvest. Table S6. The expression profiles (log2-based values) of the cassava *POD* genes after various stress treatments. Table S7. Primers used in qRT-PCR analysis. Figure S1. Phylogenetic analyses of 91 MePODs, 2 AtPRXs, 3 OsPRXs, and 3 ZmPRXs.

**Author Contributions:** W.H., X.D., and H.Y. designed the research; C.W., X.D., Z.D., and Y.Y. performed the research; X.D., W.T., C.W., and Y.W. analyzed the data; X.D. and C.W. wrote the paper; W.H., Z.D., and H.Y. reviewed the paper. All authors have read and approved the final manuscript.

**Funding:** This research was funded by the Natural Science Foundation of Hainan Province (318MS092), the National Natural Science Foundation of China (31771859), the Central Public-Interest Scientific Institution Basal Research Fund for Chinese Academy of Tropical Agricultural Sciences (1630052016005, 1630052016006, 1630052017021, 1630012019009, 1630052019023), the Central Public-Interest Scientific Institution Basal Research Fund for Innovative Research Team Program of CATAS (17CXTD-28, 1630052017017), and the earmarked fund for Modern Agro-industry Technology Research System (CARS-11).

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