Transcriptome Analysis of Petunia ×hybrida under Water Stress Using RNA Sequencing

Water deficit is a major environmental constraint to plant growth and development resulting in severe crop loss. While physiological and molecular experiments using individual genes have been extensively studied in various crops with regard to water stress tolerance, genome-wide understanding of water stress response in bedding plants is still limited. The objective of this research was to perform RNA sequencing and analyze transcriptome of Petunia ×hybrida ‘Mitchell Diploid’ under water stress. Nine-week-old petunias were irrigated daily or placed under water stress by withholding water. Leaf tissue samples were collected 1, 3, and 5 days after water was withheld. Gene expression profiling under water stress were examined using RNA sequencing. Nearly 170 million reads were sequenced by Illumina Hiseq 1500, and de novo assembly using Trinity software generated 58,628 contigs. Among all contigs, 179, 3370, and 1064 were upregulated and 84, 2416, and 250 were downregulated on day 1, 3, and 5, respectively. Gene Ontology (GO) annotation was carried out by Blast2GO. Among differentially expressed genes, genes encoding regulatory proteins such as signaling factors and transcription factors were differentially expressed at the early stage of water stress. The transcriptome data from this research will provide valuable genetic information for understanding water stress-responsive networks as well as engineering petunia with enhanced water stress tolerance.