| As an important grain feed forage,oat plays an important role in livestock farming,miscellaneous crop utilization and annual artificial grassland planting.BYDV is an infectious disease caused by barley yellow dwarf virus,which often causes symptoms such as leaf discoloration and plant dwarfing,seriously affecting oat yield and quality.In recent years,with the expansion of planting area and frequent inter-regional planting,the severity of BYDV has been increasing.Understanding the specific mechanism of oat response to BYDV infection is an urgent problem.In our study,the resistant material MN10253 and the susceptible variety Qingyin 1 were selected.The endogenous phytohormone content,protective enzyme and detoxification enzyme activity of the leaves sampled at different time points of virus infection were determined.Transcriptome sequencing and metabolome analysis were performed subsequently.Finally,the disease resistance mechanism was preliminarily analyzed by multi-omics combined with physiological indicators.(1)The contents of five endogenous phytohormone in leaves of resistant and susceptible materials at 7 time points after virus infection were determined.The results showed that the contents of auxin,gibberellin,cytokinin,abscisic acid and salicylic acid in MN10253 were higher than those in Qingyin 1 at most time points,indicating that the endogenous phytohormone of MN10253 were more responsive to virus infection.The ratio of three growth-promoting phytohormones(auxin,gibberellin,cytokinin)to ABA decreased with the prolongation of stress time,indicating that oat plants resisted stress by reducing the content of growth-promoting phytohormones and increasing the content of growth-inhibiting phytohormones.Correlation analysis showed that there was a significant negative correlation between different growth-promoting phytohormones and growth-inhibiting phytohormones in the two materials,indicating that the different responses to virus infection.(2)The activities of three protective enzymes and four detoxification enzymes of MN10253 and Qingyin 1 leaves were measured at 7 time points after infection.The activities of the three protective enzymes were higher in the resistant materials than the susceptible varieties at most time points.Acid phosphatase and alkaline phosphatase showed opposite trends between the two materials,and alkaline phosphatase activity was lower than acid phosphatase,indicating that acid phosphatase played a major role in detoxification and phosphorus efficient transport under virus infection.The activity of polyphenol oxidase increased continuously after virus infection,while the phenylalanine ammonia lyase decreased first and then increased,and the activity of resistant materials was higher than susceptible varieties,indicating that these two resistance-related enzymes may respond at different time points under virus infection.(3)Transcriptome sequencing and sequential expression analysis were pe rformed on leave samples at 5 time points after virus infection of the two mat erials.PCA results showed that the gene expression of resistant material at 2 h was significantly separated from other time points,which was an important time point for resistance generation.A total of 10,288 DEGs were obtained from 30 libraries,and the peak of DEGs appeared at 2 h and 48 h.There were 60 and 127 common regulated genes in the five comparison groups.KEGG enrich ment analysis showed that sphingolipid metabolic pathways were significantly enriched at all time points.A total of 3,828 differentially expressed TFs,which distributed in 20 TF families were predicted.Among them,RLK-Pelle-DLSV,MYB-related,b ZIP,b HLH and NAC are the most common transcription factor families.WGCNA analysis identified 14 and 18 gene modules in resistant / susceptible materials,respectively,correlation analysis with physiological indicators showed that 6 key disease resistance modules were related to phytohormone signal transduction and sphingolipid metabolic pathways.A total of 14 key disease resistance genes were screened in key modules and related pathways,and 8 hub genes were identified by PPI analysis,which may be directly related to disease resistance response.(4)The metabolome of leaf samples of two materials at three time points after virus infection were analyzed.The results of PCA showed that PC1 could clearly distinguish the two materials,indicating that they had different responses to the virus.The metabolites of resistant materials were significantly separated from other time points at 48 h,indicating that the metabolites changed significantly.A total of 678 metabolites were annotated in the three comparison groups.A total of 318,343 and 327 differential metabolites were obtained in the three comparison groups,of which 194,176 and 209 were common differential metabolites.Most of the metabolites in the resistant materials were up-regulated at 48 h,which may be an important response in the process of disease resistance.53,61 and 63 differential metabolites were enriched by KEGG analysis in the three comparison groups,respectively.Phenylpropanoid biosynthesis pathway,flavonoid and flavonol biosynthesis pathway,ABC transport pathway,zeatin biosynthesis pathway,and amino acid metabolism pathway may be the key pathways in response to viral infection.(5)Combined transcriptome and metabolome analysis were performed on leave samples at three time points after infection of the two materials.40,55 and 51 coenrichment pathways were found in the three comparison groups,respectively.It was found that the DEGs and DAMs of resistant / susceptible materials were mainly enriched in flavonoid-related pathways,phenylalanine-related pathways,photosynthetic-related pathways,alkaloid-related pathways and terpene-related pathways.Combined analysis of five types of disease resistance-related metabolic pathways showed that disease-resistant varieties mainly responded to virus infection by up-regulating the expression of anthocyanin reductase,chalcone synthase,flavonol synthase,primary amine oxidase,sedum heptulose diphosphatase,primary amine oxidase,tropinone reductase,acyclic sesquiterpene synthase and other related genes,as well as the accumulation of metabolites content such as flavonoids,isovitexin and acacetin,L-phenylalanine,eugenol,coumarin,sedum heptulose 1,7-diphosphate,salidroside,L-phenylalanine,L-piperidinecarboxylic acid,trans-cinnamic acid and other metabolites.Correlation network analysis found that some differential genes had a co-regulation relationship with metabolites,which could be focused on in the future. |
PDF Full Text Request