| Melatonin(MT)is a pleiotropic amine hormone neuroendocrine hormone.Studies in animals suggest that melatonin had an adjuvant treatment for disease,anti-aging and neuroprotection.At present,although the botanical effects of melatonin have made great progress,the specific molecular mechanism remains to be resolved.It was known that 5-hydroxytryptamine N-acetyltransferase(SNAT)was the rate-limiting enzyme in the synthesis of melatonin.This study investigated whether endogenous melatonin was involved in plant salt tolerance by cloning the SNAT gene and related genetic manipulations.Methane(CH4)has anti-inflammatory,anti-cancer and anti-oxidation effects in animals.In recent years,the botanical role of CH4 has also received increasing attention.Studies have confirmed that CH4 is involved in plants in response to a variety of abiotic stresses.Similarly,Heme oxygenase 1(HO1/HY1)also has a physiological effect similar to that of CH4.For example,both CH4 and HY1 have been found to increase the salt tolerance of plants,but it is not clear whether there is interaction between them.In response to the above scientific problems,this study used wild-type Arabidopsis(Wild-type,WT),HY1 mutant(hy1-100),HY1 overexpression(35S:HY1-4)and CH4 synthetase overexpression material(MtMCR).For the main research materials,through genetics and molecular biology,try to analyze whether there is interaction between CH4 and HY1 in the salt tolerance process of plants.The specific research results are as follows:(1)Firstly,the SNAT gene(MsSNAT)of alfalfa was cloned,and two strains of melatonin synthase overexpressing Arabidopsis MsSNAT(MsSNAT-1 and MsSNAT-2)were further obtained.It was found that MsSNAT overexpression significantly increased the endogenous melatonin content of transgenic Arabidopsis,there by increasing its salt tolerance;the number of autophagy and autophagy-associated(ATG)gene expression analysis confirmed by sulfonylar cadaverine(MDC)staining;the endogenous melatonin-induced plant salt tolerance was associated with autophagosome enhancement.Overexpression of MsSNAT also participates in the rebuilding of redox balance under salt stress by increasing the activity of antioxidant enzymes/gene expression,thus enhancing the salt tolerance of Arabidopsis thaliana.Molecular biology experiments show that overexpression of MsSNAT can also participate in the reconstruction of ion homeostasis by modulating the ion transporters of sodium and hydrogen transporters(NHX1)and salt allergy 1(SOS1).In conclusion,the above genetic and molecular biology results confirm that melatonin enhances salt tolerance in Arabidopsis thaliana through the following factors:1)enhancing intracellular autophagy;2)participating in rebuilding redox balance and ion homeostasis of seedlings under stress.(2)Real-time quantitative PCR and GUS staining analysis confirmed that exogenous CH4(provided as methane-rich water)pretreatment could enhance the expression of wild-type HY1 under salt treatment;exogenous CH4pretreatment could enhance 35S:HY1-4 salt tolerance of Arabidopsis thaliana,but does not alter the salt sensitivity of the hy1-100 mutant,which is not the same as the result of CO pretreatment.Molecular biology studies have shown that HY1 participates in CH4 to improve salt tolerance in Arabidopsis thaliana by increasing the expression of SOS1 gene,antioxidant enzyme gene and microRNAs.In addition,exogenous CH4 pretreatment could also reduce the contents of Na+/K+,reactive oxygen species(hydrogen peroxide and superoxide anion)and TBARS in 35S:HY1-4 Arabidopsis strains,but no similar effect was found in hy1-100 mutants.Further genetic studies showed that ZnPP,an inhibitor of HY1,reduced the salt tolerance of Arabidopsis thaliana MtMCR In conclusion,this study revealed that CH4 participates in alleviating salt stress in Arabidopsis thaliana by modulating the HY1 signal.The above studies provide preliminary theoretical and practical knowledge for improving plant salt tolerance. |
PDF Full Text Request