Integrated Single-Molecule Long-Read Sequencing and Illumina Sequencing Reveal the Resistance Mechanism of Psathyrostachys Huashanica in Response to Barley Yellow Dwarf Virus-Gav

Although Psathyrostachys huashanica has excellent potential for resistance gene mining and molecular genetic breeding, no reference genome is available. To date, most studies of P. huashanica have been focused on the creation of translocation lines and additional lines, as well as the development of molecular markers. Therefore, research at the transcriptional level is lacking. In this study, the full-length transcriptome of P. huashanica was sequenced using PacBio isoform sequencing (Iso-Seq) of a pooled RNA sample to explore the potential full-length transcript isoforms. We obtained 112,596 unique transcript isoforms with a total length of 114,957,868 base pairs (bp). Subsequently, Illumina sequencing reads were used to correct and trim the PacBio isoforms. We annotated 103,875 unigenes in at least one functional database, and identified a plethora of differentially-expressed genes (DEGs) that are involved in the defense responses of P. huashanica against barley yellow dwarf virus-GAV (BYDV-GAV). Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis revealed that these DEGs were mostly involved in plant-pathogen interaction, plant hormone signal transduction, and the mitogen-activated protein kinase (MAPK) signaling pathway. Additionally, we selected twenty of the RNA-seq identified resistance-related up-regulated genes, including MAPKs, cysteine-rich receptor-like protein kinases (CRPKs), calcium-dependent protein kinases (CDPKs), pathogenesis-related protein (PR) proteins, WRKYs, and disease resistance proteins, and validated their up-regulation in response to BYDV-GAV by quantitative real-time PCR. Our results indicate that a series of defense-related genes were induced in P. huashanica during BYDV-GAV infection. The full-length transcriptome dataset will contribute to improved use of stress-resistance genes of P. huashanica, and serves as a reference database for the analysis of transcript expression in P. huashanica.