Molecular Mechanism Underlying the Sorghum sudanense (Piper) Stapf. Response to Osmotic Stress Determined via Single-Molecule Real-Time Sequencing and Next-Generation Sequencing

Abstract

Drought, as a widespread environmental factor in nature, has become one of the most critical factors restricting the yield of forage grass. Sudangrass (Sorghum sudanense (Piper) Stapf.), as a tall and large grass, has a large biomass and is widely used as forage and biofuel. However, its growth and development are limited by drought stress. To obtain novel insight into the molecular mechanisms underlying the drought response and excavate drought tolerance genes in sudangrass, the first full-length transcriptome database of sudangrass under drought stress at different time points was constructed by combining single-molecule real-time sequencing (SMRT) and next-generation transcriptome sequencing (NGS). A total of 32.3 Gb of raw data was obtained, including 20,199 full-length transcripts with an average length of 1628 bp after assembly and correction. In total, 11,921 and 8559 up- and down-regulated differentially expressed genes were identified between the control group and plants subjected to drought stress. Additionally, 951 transcription factors belonging to 50 families and 358 alternative splicing events were found. A KEGG analysis of 158 core genes exhibiting continuous changes over time revealed that ‘galactose metabolism’ is a hub pathway and raffinose synthase 2 and β-fructofuranosidase are key genes in the response to drought stress. This study revealed the molecular mechanism underlying drought tolerance in sudangrass. Furthermore, the genes identified in this study provide valuable resources for further research into the response to drought stress.

Selection and Validation of Reference Genes in Sudan Grass (Sorghum sudanense (Piper) Stapf) under Various Abiotic Stresses by qRT-PCR

“…cording to transcriptomic data of Sudan grass under drought stress [26]. They belo COR (Isoform0007606) and MAPK (Isoform0002387).…”

“…To ensure the dependability of the rankings for the reference genes, the relative expression trend in the target genes was analyzed using the two most stable reference genes (eIF4α, PP2A), one combined reference gene (eIF4α + PP2A), and the most unstable reference gene (Actin) under drought stress. Two target genes (Isoform0007606 and Isoform0002387) that belong to the drought-stress-response genes are highly expressed according to transcriptomic data of Sudan grass under drought stress [26]. They belong to COR (Isoform0007606) and MAPK (Isoform0002387).…”