Phylogenetic and expression analysisof polyamine oxidase (PAO) genes in maize (Zea mays L.)

Polyamines are oxidativelydeaminated by amine oxidases (AOs), including copper amine oxidases (CuAOs) and FAD-dependent polyamine oxidases (PAOs). PAOs are associated with polyamine catabolism in peroxisome, apoplast and cytoplasm. In plants, increasing evidences support that PAO genes play an essential roles in growth and developmental processes such as organogenesis, senescence, and also responses to abiotic and biotic stresses. The availability of the maize genome sequences has provided an excellent opportunity for whole-genome annotation, classification and comparative genomics research. In this study, through bioinformatics analysis approaches, nine putative PAO (ZmPAO1–ZmPAO9) were identified in maize genome. According to Phylogenetic analysis ZmPAOs can be divided into three major groups as found in their orthologous in Arabidopsis and rice. It is also demonstrated that maize PAO proteins are more closely related to rice than those in Arabidopsis. Gene structural analysis showed that the ZmPAOs have zero to nine introns and they are distributed across 4 out of 10 chromosomes in maize. Duplication pattern analysis shows that segmental and tandem duplication are the main reasons for maize PAOs expansion. Using public microarray data, the roles of ZmPAOs in growth and development processes were assessed. These results have been provided evidences regarding the important functions of the gene family in maize developmental regulation. These results provide a basis for further functional characterization of ZmPAOs at the tissue/developmental level and in response to stresses. Using public microarray data, ZmPAO expression profiles strongly suggested that ZmPAOs have a role in growth and development processes.