Transcriptomic changes associated with husk scald incidence on pomegranate fruit peel during cold storage

Pomegranate fruit is valued for its social, economic, aesthetic and health benefits. The fruit rapidly loses quality after harvest due to continued metabolic responses and physiological disorders under sub-optimal conditions. The incidence of physiological disorder such as husk scald manifests during storage and commercial shipping, which affects the appearance and limits marketability. Despite the importance of pomegranate husk scald, little information is available about the origin and molecular mechanisms. Therefore, the aim of this study was to investigate the scald incidence of pomegranate fruit at molecular level using RNA-Seq (Ion Proton™ Next Generation Sequencing) by analyzing peel transcriptomic changes. The RNA-seq analysis generated 98,441,278 raw reads. 652 Differentially Expressed Genes (DEGs) with a fold change of > |2|, a p value ≤ 0.05 and a false discovery rate (FDR) of <0.05 were identified between healthy and scald fruit peels. An analysis of the gene ontologies of these DEGs revealed the 432 genes were assigned with molecular functions, 272 as cellular components and 205 as part of biological processes. In this analysis, genes (Pgr023188 and Pgr025081) that encode uncharacterized protein and gene (Pgr007593) that encodes glycosyltransferase showed significantly highest fold changes. Genes (Pgr003448, Pgr006024 and Pgr023696) involved in various iron binding and oxidoreductase activities were significantly suppressed. This is the first transcriptome analysis of pomegranate fruit peel related to husk scald development. Results obtained from this study will add valuable information on husk scald related changes on pomegranate fruit at genomic level and provide insight on other related physiological disorders.