Overexpression of PpSnRK1α in tomato enhanced salt tolerance by regulating ABA signaling pathway and reactive oxygen metabolism

Background SNF-related Kinase 1 (SnRK1) is a key component of the cell signaling network. SnRK1 is known to respond to a wide variety of stresses, but its exact role in salt stress response and tolerance is still largely unknown. Results In this study, we reported that overexpression of the gene encoding the alpha subunit of Prunus persica SnRK1 (PpSnRK1 alpha) in tomato could improve salt stress tolerance. The increase in salt stress tolerance in PpSnRK1 alpha-overexpressing plants was found to correlate with increased PpSnRK1 alpha expression level and SnRK1 kinase activity. And PpSnRK1 alpha overexpression lines exhibited a lower level of leaf damage as well as increased proline content and reduced malondialdehyde (MDA) compared with wild-type (WT) lines under salt stress. Furthermore, PpSnRK1 alpha enhanced reactive oxygen species (ROS) metabolism by increasing the expression level of antioxidase genes and antioxidant enzyme activities. We further sequenced the transcriptomes of the WT and three PpSnRK1 alpha overexpression lines using RNA-seq and identified about 1000 PpSnRK1 alpha-regulated genes, including many antioxidant enzymes, and these genes were clearly enriched in the MAPK signaling pathway (plant), plant-pathogen interactions and plant hormone signaling transduction and can respond to stimuli, metabolic processes, and biological regulation. Furthermore, we identified the transcriptional levels of several salt stress-responsive genes, SlPP2C37, SlPYL4, SlPYL8, SlNAC022, SlNAC042, and SlSnRK2 family were altered significantly by PpSnRK1 alpha, signifying that SnRK1 alpha may be involved in the ABA signaling pathway to improve tomato salt tolerance. Overall, these findings provided new evidence for the underlying mechanism of SnRK1 alpha conferment in plant salt tolerance phenotypes. Conclusions Our findings demonstrated that plant salt stress resistance can be affected by the regulation of the SnRK1 alpha. Further molecular and genetic approaches will accelerate our knowledge of PpSnRK1 alpha functions, and inform the genetic improvement of salt tolerance in tomato through genetic engineering and other related strategies.