Transcriptome Analysis and Genes Function Verification of Root Development of Paeonia suffruticosa under Sandy Loam Cultivation

Abstract

Relatively poor in vitro rooting has limited the large-scale commercial production of tree peony. In this study, on the basis of transcriptome sequencing, differentially expressed genes and the associated metabolic pathways were identified in tree peony roots at different stages of root formation under sandy loam cultivation. A total of 31.63 Gb raw data were generated and 120,188 unigenes (mean length of 911.98 bp) were annotated according to six databases (NR, NT, GO, KEGG, COG, and Swiss-Prot). Analyses of the ungerminated root primordium period, induced root primordium period, and root formation period detected 8,232, 6,907, and 10,687 differentially expressed genes related to 133, 132, and 133 metabolic pathways, respectively. Two significantly differentially expressed genes (Unigene13430_All and CL10096.Contig1_All) were associated with the auxin pathway. The full-length Unigene13430_All coding sequence (843 bp) encoded 280 amino acids, whereas the full-length CL10096.Contig1_All coding sequence (1,470 bp) encoded 489 amino acids. Unigene13430_All and CL10096.Contig1_All were identified as IAA gene family members and were respectively named PsIAA27 and PsARF19. The qRT-PCR analysis and functional verification indicated that the expressions of PsARF19 and PsIAA27 in tree peony seedlings, cuttings and grafted seedlings were significant different. PsARF19 promoted root development, it might be a regulatory gene related to the formation of tree peony roots, while PsIAA27 inhibited lateral root development, and it might be involved in controlling auxin sensitivity during root formation. The results of this study may form the basis of future investigations on the mechanism mediating peony root formation. The transcriptome data will be an excellent resource for researchers interested in characterizing the rooting-related tree peony genes.