Genome-Wide Identification and Expression Analysis of MAPK and MAPKK Gene Family in Pomegranate (Punica Granatum L.)

Mitogen-activated protein kinase (MAPK) cascade is involved in the regulation of a series of biological processes in organisms, which are composed of MAPKKKs, MAPKKs, and MAPKs. Although genome-wide analyses of it has been well described in some species, little is known about MAPK and MAPKK genes in pomegranates. In this study, we identified 18 PgMAPKs, 9 PgMAPKKs through a genome-wide search. Chromosome localization showed that 27 genes are distributed on 7 chromosomes with different densities. Multiple sequence alignment and phylogenetic analysis revealed that PgMAPKs and PgMAPKKs could be divided into 4 subfamilies (groups A, B, C, and D), respectively. In addition, exon-introns structural analysis of each candidate gene has indicated high levels of conservation within and between phylogenetic groups. Cis-acting element analysis predicted that PgMAPKs and PgMAPKKs were widely involved in the growth, development, stress and hormone response of pomegranate. Expression profile analyses of PgMAPKs and PgMAPKKs were performed in different tissues (root, leaf, flower and fruit), and PgMAPK13 was significantly expressed in all tissues. To our knowledge, this is the first genome-wide analysis of the MAPK and MAPKK gene family in pomegranate. This study provides valuable information for understanding the classification and functions of pomegranate MAPK signal.