Transcriptome sequencing and gene expression profiling of Populus wutunensis, a natural hybrid, during salinity stress

Abstract

When Populus wutunensis seedlings are salt stressed, many genes involved in cellular metabolism, signal transduction, transport, osmotic regulation, and reactive oxygen species scavenging show elevated expression levels. Populus wutunensis, a natural hybrid individual resulting from a cross between Populus × xiaozhuanica W. Y. Hsu et Liang, shows salt and drought tolerance and is fast-growing. It is widely cultivated in the Three-North Shelterbelt Forest area in China. To determine the transcriptome changes in P. wutunensis under salt stress, RNA-seq was conducted in salt-treated leaves and non-salt-treated control leaves. A total of 81,188 unigenes, with an average length of 982 bp, were obtained. In salt-treated leaves, 2466 differentially expressed genes were identified that differed from those in control leaves at any time point. Among them, 391 were upregulated and 44 were downregulated during all salt stress time points. They were mainly involved in cellular and metabolic processes, signal transduction, transport, osmotic regulation, and reactive oxygen species (ROS) scavenging. In addition, 2543 transcription factor genes were identified and divided into 60 families. qRT-PCR analysis revealed that the levels of differentially expressed genes were consistent with those from sequencing of the transcriptome under salt stress. These findings will increase our understanding of gene regulation in response to salt stress in P. wutunensis and are beneficial for future research on molecular-assisted breeding.