| Salt stress is different from alkali stress.It has been shown that alkali stress does more damage to oats than salt stress.Elucidating the physiology and metabolism and genes mechanisms under plant saline stress will help to further optimize breeding and cultivation to improve saline field crop yield.Therefore,in this study,we analyzed the different mechanisms of oat under salt and alkali stress by analyzing the differences in physiological indicators and metabolic pathways and gene transcript expression under salt and alkali stress conditions.The main results are as follows:1.Osmotic regulation and antioxidant regulation and ion balance participate in the response process of oat response to salt stress or alkali stress.The leaves maintain the ion balance by accumulating Cl~-under salt stress,and by accumulating organic acid as the main aconic acid under alkali stress.The aconitic acid and citric acid are the main components of organic acids with alkali stress.2.There are different metabolic pathways of oat leaves response to salt and alkali stress.(1)Comparing with alkali stress,salt stress causes a more abundant metabolic path response in oat leaves.Among them,lipid metabolism and organic acid are the main ways of oat leaf differential metabolism under salt stress and alkali stress conditions respectively.(2)There are differences in the catcher acid pathway and pyruvate metabolism and TCA cycle of responding salt stress and alkali stress in oat leaves.Salt stress increased tryptophan and decreased quinacid in oat leaf.Alkali stress is the opposite.Pyruvate kinase accumulates in large quantities under alkali stress,however,it does not change significantly under salt stress.Furthermore,organic acid metabolites accumulate the TCA cycle only under alkali stress,and the main organic acid component is aconic acid.(3)It is speculated that the metabolic regulation mechanism of aconic acid accumulation may be the increased upstream synthesis of aconic acid and the reduced consumption of aconic acid.The increase of pyruvate kinase and the reduced plant water content are the key metabolic and physiological regulatory factors to promote the accumulation of aconic acid,which conforms to the"broaden sources of income&reduce expenditure"mode in the metabolic pathway.3.There are different transcriptional regulation mechanisms of oat leaves response to salt and alkali stress.(1)The number of differentially expressed genes(DEGs)in oat leaves in response to alkali stress is more in salt stress.(2)The GO enrichment analysis found that the DEGs of oat leaves under salt stress were enriched in nucleic acid binding,cell wall,external encapsulation structure,extracellular domain and nucleotide binding items,The DEGs under alkali stress were enriched in cell components,metabolic synthesis,amino acids and other items;Analysis of the KEGG pathway enrichment analysis revealed that,DEGs under salt stress were enriched in metabolic pathways,signal transduction pathways,plant pathogen interactions,amino acid metabolism pathways,such as carbon metabolism and signaling,however,the DEGs under alkali stress were enriched in the TCA cycle,glycolysis,pentose phosphate pathway,sucrose,and starch metabolism pathways.(3)The patterns of DEGs expression between salt stress and alkali stress are different:The DEGs are more abundant than salt stress when it is under the alkali stress.The DEGs in the pyruvate metabolic pathway are lower with salt stress,while the DEGs overexpression in TCA cycle and glyoxylate cycle.The patterns of DEGs expression with alkali stress is the opposite,the DEGs are overexpressed in the pyruvate metabolism pathway,whereas,the expression of DEGs in the TCA cycle and glyoxylate cycle are lower.(4)Under the alkali stress,the DEGs expression related to aconic acid show that,the expression of DEGs in the upstream of aconic acid synthesis pathway is overexpressed,but it is lower in downstream.The transcriptional regulation mechanism also conforms to the mode of"open source and reducing expenditure"when the aconic acid in response to alkali stress.The gene of PEPC2 plays an important role in regulating the accumulation of organic acid metabolism under alkali stress.In conclusion,it’s different to responses to two types of stress in metabolic and gene regulation on the organic acid pathway,the leaf response to alkali stress by accumulating organic acid,and organic acid is used on the ways of ion balance regulation,and it is regulated by the pathways of metabolic and transcription. |
