| Using winter fallow fields for highland barley cultivation can not only fully utilize land resources,but also improve the multiple cropping index and unit area yield.However,in most areas of the southwest,there is less drought and rainfall in winter,resulting in a lower yield of highland barley.Therefore,this experiment aims to study the drought resistance of highland barley.As a crop with strong drought resistance,the drought resistance mechanism of highland barley is studied,It is of great significance for studying the drought resistance of other crops and for breeding highland barley.In this study,two highland barley varieties with different drought resistance,Dianqing1 and Dianqing 2,were selected for drought stress at the seedling stage.Growth and development characteristics and physiological indicators were measured at 0 h,24 h,48 h and 72 h of drought treatment,and transcriptome analysis was carried out.The research results are as follows:(1)As the drought duration prolonged,the plant height,seedling dry matter,root dry matter,and root length of the two strains gradually decreased,while the root to shoot ratio gradually increased.It was found that the growth and development characteristics of the Dianqing 1 strain with strong drought resistance were better than those of the Dianqing 2strain with weak drought resistance.The physiological indicators of leaf water content and chlorophyll content gradually decrease with the prolongation of drought stress treatment;After 24 hours of drought treatment,the MDA content was the lowest and gradually increased;The contents of soluble sugar,abscisic acid and jasmonic acid all increased gradually at first and reached the maximum at 48 h,and then decreased gradually.Compared with Dianqing 2,the growth rate of leaf water content of Dianqing 1 was lower,and the growth rate of MDA content was higher.At 48 h,the content of abscisic acid of Dianqing 1 was higher than that of Dianqing 2,indicating that the drought resistance of Dianqing 1 was stronger than that of Dianqing 2.(2)Transcriptome data showed that Dianqing 1 had 316 and 1909 differential genes in the control and 48 h treatment(D1-0vsD1-48)and Dianqing 2 had 1909 differential genes in the control and 48 h treatment(D2-0vsD2-48),respectively.G0 pathway analysis found that protein containing complexes and cellular anatomical entities were significantly enriched in cell grouping,cell processes and metabolic processes were significantly enriched in biological processes,and catalytic activity and binding were significantly enriched in molecular functional classes.In biological processes,the regulation of biological processes and response to stimuli were only significantly enriched in the comparison group of Dianqing 1 treated with control and 48 h treatment(D1-0vsD1-48).The KEGG pathway was found to be significantly enriched in the biosynthesis of secondary metabolites,metabolic pathways,plant pathogen interactions,plant hormone signaling,MAPK signaling pathways-plant,starch,and sucrose metabolism.The co expression network indicates that Dianqing 2 mainly undergoes a series of intracellular reactions under drought treatment in the comparison group of control and 48 h treatment(D2-0vsD2-48),while Dianqing 1 mainly undergoes reactions in cell structure,metabolic processes,etc.in the comparison group of control and 48 h treatment(D1-0vsD1-48).The gene expression changes of Dianqing 2 in different pathways of metabolism were more significant in the control and 48 h treatment(D2-0vsD2-48)than in Dianqing 1 in the control and 48 h treatment(D1-0vsD1-48),which may be due to the more active or faster stress response of Dianqing 2 during drought.(3)Under transient drought stress,analysis of two strains revealed that the expression of genes in the NAC candidate transcription family(HORVU.MOREX.R3.2 HG0111350 and HORVU.MOREX.R3.1 HG0074840),AP2/ERF ERF family(CBF1 and HORVU.MOREX.R3.7 HG0665380),MYB related family(HORVU.MOREX.R3.2 HG0196050 and CCA1),and WRKY family(HORVU.MOREX.R3.3 HG0284810)may play a major role.It was also found that genes regulating other stresses,such as CBF1,CBF14 and CCA1 also played a role in this experiment,indicating the complexity between drought stress and other stresses.These results provide new ideas and resources for the research and cultivation of drought resistant barley strains in the future.In the metabolism of starch and sucrose,many genes were found to be expressed in Dianqing 2 under control and 48 h treatment(D2-0vsD2-48),and fructose kinase β-Glucosidase,glucose-1-phosphate adenylate transferase α-Amylase was expressed in both treatment groups,indicating that these enzymes play a role under short-term drought treatment.In the analysis of jasmonic acid and abscisic acid in hormone signal transduction,it was found that most of jasmonic acid was expressed in the control and 48 h treatment(D2-0vsD2-48)of Dianqing 2,while Dianqing 1 was less expressed in the control and 48 h treatment(D1-0vsD1-48),indicating that Dianqing 1 may have a slower rate of jasmonic acid synthesis under drought stress,and both treatment groups have significant effects on abscisic acid.To sum up,it can be seen from the physiological index data that the drought resistance of Dianqing 1 is stronger than that of Dianqing 2,and the indexes have increased to varying degrees after 48 h of drought treatment.Therefore,transcriptome research shows that Dianqing 2 activates more differential genes under the comparison of control and 48 h treatment(D2-0vsD2-48),and starch and sucrose metabolism and hormone signal transduction process play an important role in it,transcription NAC,WRKY,MYB and other families have played an important role in the drought resistance process of highland barley,and other stress control factors have also been found to appear in this process,indicating the complexity of short-term drought resistance in highland barley. |
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