*Article* **The Class III Peroxidase (POD) Gene Family in Cassava: Identification, Phylogeny, Duplication, and Expression**

**Chunlai Wu 1,2,**† **, Xupo Ding 1,**† **, Zehong Ding <sup>1</sup> , Weiwei Tie <sup>1</sup> , Yan Yan <sup>1</sup> , Yu Wang <sup>3</sup> , Hai Yang 4,\* and Wei Hu 1,\***


Received: 15 April 2019; Accepted: 31 May 2019; Published: 3 June 2019

**Abstract:** The class III peroxidase (POD) enzymes participate in plant development, hormone signaling, and stress responses. However, little is known about the POD family in cassava. Here, we identified 91 cassava *POD* genes (*MePODs*) and classified them into six subgroups using phylogenetic analysis. Conserved motif analysis demonstrated that all MePOD proteins have typical peroxidase domains, and gene structure analysis showed that *MePOD* genes have between one and nine exons. Duplication pattern analysis suggests that tandem duplication has played a role in *MePOD* gene expansion. Comprehensive transcriptomic analysis revealed that *MePOD* genes in cassava are involved in the drought response and postharvest physiological deterioration. Several *MePODs* underwent transcriptional changes after various stresses and related signaling treatments were applied. In sum, we characterized the POD family in cassava and uncovered the transcriptional control of *POD* genes in response to various stresses and postharvest physiological deterioration conditions. These results can be used to identify potential target genes for improving the stress tolerance of cassava crops.

**Keywords:** expression; genome-wide; identification of peroxidase genes; duplication pattern; stress; cassava
