Using Isoform Sequencing for De Novo Transcriptome Sequencing and the Identification of Genes Related to Drought Tolerance and Agronomic Traits in Tall Fescue (Festuca arundinacea Schreb.)

Plant height and tillering are the key traits of tall fescue (Festuca arundinacea Schreb.), a perennial turf grass widely used for forage and turf worldwide. It exhibits excellent abiotic stress tolerance. However, the investigation of these traits at the genetic level is limited by the lack of a completely sequenced genome of tall fescue. Here, we generated genome-wide transcriptome data using PacBio isoform sequencing (Iso-Seq) technology. We obtained 73,628 transcripts with an average length of 2410 bp. Among these transcripts, 42,265 (60.09%) were predicted as complete full-length open reading frames. The dataset contained 11,520 simple sequence repeats; 737 bp long non-coding RNAs; and 1599 alternative splicing sites in unigenes. Sixty-three unigenes involved in abscisic acid biosynthesis, catabolism, and signaling pathways were identified. The Illumina-sequencing analysis results, further verified using qRT-PCR, revealed the significant upregulation of nine unigenes under drought stress. Ninety-three unigenes involved in controlling plant height and tillering were also identified, of which FaMAX1 was functionally verified to regulate plant tillering. Our results provide a valuable genetic resource about the complete transcriptome of tall fescue; the identified candidate genes can aid in improving the drought tolerance and agronomic traits in tall fescue and other related plants.