Genome-Wide Identification, Characterization of RDR Genes and their Expression Analysis during Reproductive Development and Stress in Pineapple

RNA-dependent RNA polymerases (RDRs), involved in the production of various small interfering RNA (siRNA), play critical roles in plant growth, development process, and abiotic/biotic stresses. In this study, 5 RDR genes (AcRDRs) were identified from the pineapple genome. Phylogenetic analysis showed that AcRDRs could be divided into 4 subgroups. Gene structure analysis showed that the number of introns varied from 2 to 18. Furthermore, we analyzed AcRDR expression patterns in vegetative organs and in sexual organs, namely ovules and stamens, at different developmental stages respectively. AcRDR2, AcRDR3 and AcRDR6b showed higher expressions in the male and female reproductive organs, while AcRDR3 also was accumulated highly in sepal and fruit. AcRDR6a exhibited the highest expression levels at the mature ovule and stamen. AcRDR1 had an expression peak in the root. Furthermore, we checked the responses of AcRDRs to abiotic stresses and phytohormones. The results of this study provided basic genomic information for AcRDRs and insights into the probable roles of these genes in plant growth and development.