Abstract
BackgroundSNF-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.ResultsIn this study, we reported that overexpression of the gene encoding the α subunit of Prunus persica SnRK1 (PpSnRK1α) in tomato could improve salt stress tolerance. The increase in salt stress tolerance in PpSnRK1α-overexpressing plants was found to correlate with increased PpSnRK1α expression level and SnRK1 kinase activity. And PpSnRK1α 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, PpSnRK1α 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 PpSnRK1α overexpression lines using RNA-seq and identified about 1000 PpSnRK1α-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 PpSnRK1α, signifying that SnRK1α may be involved in the ABA signaling pathway to improve tomato salt tolerance. Overall, these findings provided new evidence for the underlying mechanism of SnRK1α conferment in plant salt tolerance phenotypes.ConclusionsOur findings demonstrated that plant salt stress resistance can be affected by the regulation of the SnRK1α. Further molecular and genetic approaches will accelerate our knowledge of PpSnRK1α functions, and inform the genetic improvement of salt tolerance in tomato through genetic engineering and other related strategies.
Highlights
SNF-related Kinase 1 (SnRK1) is a key component of the cell signaling network
We further examined the expression levels of salt stressrelated genes that significantly correlated with SnRK1 and validated the interactions between SnRK1 and known Abscisic acid (ABA) receptors, which provide evidence for a role of SnRK1 in salt stress response, signifying that SnRK1α may be involved in the ABA signaling pathway or reactive oxygen (ROS) metabolism to improve tomato salt tolerance
These results indicate that PpSnRK1α overexpression leads to a decrease in the degree of cell membrane peroxidation and the accumulation of proline in response to salt stress
Summary
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. High salt can affect the absorption of water and nutrients and reduce photosynthesis, thereby inhibiting plant growth and causing yield loss. The salt tolerance of plants is conferred by tolerance genes. The isolation of novel tolerance genes and effective identification of salt-resistant germplasm are key strategies for improving salt tolerance in plants [3]. Extensive genetic and molecular studies using loss-of-function mutants and overexpression lines have been carried out to investigate the molecular basis of salt tolerance in model plants and crop species. Screening for salt-tolerant genes via molecular studies is a necessity for protecting the plants against salt stress
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