Peach (Prunus persica L. Batsch) is a shallow root fruit tree with poor waterlogging tolerance. Hydrogen sulfide (H 2 S) is a signal molecule which regulates the adaptation of plants to adverse environments. Nevertheless, the effects of exogenous applications of H 2 S in fruit tree species especially in peach trees under waterlogging stress have been scarcely researched. Thus, the goal of this research was to investigate the alleviating effect of exogenous H 2 S on peach seedlings under waterlogging stress. In the present study, we found that the effect of exogenous H 2 S depended on the concentration and 0.2 mM sodium hydrosulfide (NaHS) showed the best remission effect on peach seedlings under waterlogging stress. Waterlogging significantly reduced the stomatal opening, net photosynthetic rate, and Fv/Fm of peach seedlings. The results of histochemical staining and physiological and biochemical tests showed that waterlogging stress increased the number of cell deaths and amounts of reactive oxygen species (ROS) accumulated in leaves, increased the number of root cell deaths, significantly increased the electrolyte permeability, O 2. − production rate, H 2 O 2 content and ethylene synthesis rate of roots, and significantly reduced root activity. With prolonged stress, antioxidative enzyme activity increased initially and then decreased. Under waterlogging stress, application of 0.2 mM NaHS increased the number of stomatal openings, improved the chlorophyll content, and photosynthetic capacity of peach seedlings. Exogenous H 2 S enhanced antioxidative system and significantly alleviate cell death of roots and leaves of peach seedlings caused by waterlogging stress through reducing ROS accumulation in roots and leaves. H 2 S can improve the activity and proline content of roots, reduce oxidative damage, alleviated lipid peroxidation, and inhibit ethylene synthesis. The H 2 S scavenger hypotaurine partially eliminated the effect of exogenous H 2 S on alleviating waterlogging stress of peach seedlings. Collectively, our results provide an insight into the protective role of H 2 S in waterlogging-stressed peach seedlings and suggest H 2 S as a potential candidate in reducing waterlogging-induced damage in peach seedlings.

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 α subunit of Prunus persica SnRK1 (PpSnRK1α) in tomato could improve salt stress tolerance. The increase in salt stress tolerance in PpSnRK1αoverexpressing 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. Conclusions: Our 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.

Salt stress is a major adverse abiotic factor seriously affecting fruit tree growth and development. It ultimately lowers fruit quality and reduces yield. Phosphatidylcholine (PC) is an important cell membrane component that is critical for cell structure and membrane stability maintenance. In this study, we found that the addition of external PC sources significantly increased the tolerance of one-year-old peach trees, Prunus persica (L.) Batsch., to salt stress and attenuated their damage. The effect of exogenous application of 200 mg/L PC exerted the most significant positive effect. Its use caused seedling leaf stomatal opening, contributing to normal gas exchange. Moreover, beneficial effects were exerted also to the root system, which grew normally under salt stress. Meanwhile, phospholipase D activity in the cell was promoted. The production of phosphatidic acid (PA) was enhanced by increased decomposition of phospholipids; PA serves as a secondary messenger involved in plant biological process regulation and the reduction in the reactive oxygen species- and peroxide-induced damage caused by salt stress. The possible mechanism of action is via promoted plant osmotic regulation and tolerance to salt stress, reducing salt stress-induced injury to plants.

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