| Quinoa(Chenopodium Willd.)is an annual dicotyledonous plant of the genus Quinoa in the family Amaranthaceae.Its grain is rich in high-quality complete protein,a variety of amino acids,and nutritional value.Quinoa has strong drought tolerance,but the physiological and molecular mechanisms of drought resistance are still unclear.Therefore,in this study,PEG-6000 was used to simulate drought stress,and 23 quinoa germplasm resources were evaluated for drought resistance at germination stage.On this basis,the effects of gradient drought stress on the growth,development and photosynthetic index of different drought-resistant quinoa were studied by potted water control method,and the physiological mechanism of quinoa response to drought stress was elucidated.And through transcriptome sequencing(RNA-seq)and differential metabolic gene expression analysis,non-target metabolomics(LC-MS)and differential metabolite identification of quinoa with different drought resistance under drought stress,quinoa drought resistance genes and drought marker metabolites were excavated,and the molecular mechanism of quinoa response to drought stress was revealed.hoping to lay a theoretical foundation for the study of drought resistance of quinoa.The main results of this thesis are as follows:(1)PEG-6000 was used to simulate drought stress.Taking germination potential,germination rate,germination index,vigor index,bud length,root length,root shoot ratio and biomass as identification indexes,the drought resistance of 23 quinoa at germination stage was comprehensively evaluated by means of principal component,cluster and stepwise regression analysis.The tested quinoa can be divided into three drought resistance grades: strong,moderate,sensitive.The determination of root length,vigor index and germination rate can be used as the effective indicators to identify and predict the drought resistance at germination stage.(2)With the increase of drought stress,the plant height,biomass and root shoot ratio of drought-resistant varieties D2 and LL1 all showed a trend of first increasing and then decreasing,and the biomass and root shoot ratio of drought sensitive ZK1 decreased.The relative water content of D2,LL1 and ZK1 decreased continuously,while the root viability increased first and then decreased.CAT and SOD activities of D2 and LL1 were increased first and then decreased,POD activity decreased first and then increased,CAT and POD activities of ZK1 were decreased continuously,and SOD decreased first and then increased;The contents of chlorophyll b and total chlorophyll of the three quinoa varieties for testing increased with drought stress,and the contents of chlorophyll a of drought resistant varieties D2 and LL1 were higher than those of the control under severe stress.Under severe stress,the net photosynthetic rate,transpiration rate and water use efficiency of D2 and LL1 were significantly higher than those of ZK1.The effects of drought stress against drought resistant varieties D2 and LL1 were less than those of sensitive varieties.Under drought stress,quinoa has a regulatory mechanism of actively removing reactive oxygen species,accumulating chlorophyll,and protecting photosynthetic system.(3)Drought resistant varieties D2 and LL1 and drought sensitive variety ZK1 were sequenced after 48 hours simulate drought stress by 30% PEG-6000.Of the 8799 new genes obtained,a total of 4587 new genes were annotated.After data analysis,D2,LL1 and ZK1 identified 234 DEGs,1756 DEGs,764 DEGs.Up regulation of DEGs is mainly involved in amino acid metabolism and lipid metabolism,phenylpropane biosynthesis,signal transduction and other pathways.Down regulation of DEGs are mainly involved in carbon metabolism,nitrogen metabolism,glucose metabolism and other pathways.The relative expression of q RT-PCR was basically consistent with the expression of FPKM of RNA-seq,indicating that the sequencing data of leaf transcriptome of quinoa seedlings was reliable.(4)Under the same conditions as the materials and experimental conditions of transcriptome sequencing.The non-targeted metabolomics analysis of quinoa varieties with different drought resistance showed that D2,LL1 and ZK1 identified 595 kinds of DEMs(pos),610 kinds of DEMs,483 kinds of DEMs.D2、LL1 and ZK1 identified 202 kinds of negative ions(neg),357 kinds of DEMs,265 kinds of DEMs,among which the number of up-regulated metabolites > down-regulated metabolites.Under drought stress,the differential metabolites of quinoa were mainly concentrated in amino acids and derivatives,fatty acids,sugars,polyphenols and various secondary metabolites.(5)Combined analysis of transcriptome and metabolome data showed that DEGs and DEMs with high correlation coefficient were mainly enriched in amino acid metabolism,lipid metabolism,carbohydrate metabolism,secondary metabolite synthesis pathway,hormone and signal transduction pathway.Among them,shikimic acid and Phenylpyruvate(4-hydroxyphenylpyruvate acid)were significantly correlated with branched acid mutase,UDP glycosyltransferase;Marker metabolites in lipid metabolism α-Linolenic acid,jasmonic acid were significantly correlated with phospholipases A1,AOS and LOX;The marker metabolites glycogen was significantly correlated with 17 DEGs such asβ-Glucosidase,sucrose synthase,glucose-1-phosphate adenylate transferase and fructose kinase in carbohydrate compounds;The marker metabolites ferulic acid,trans cinnamic acid,caffeic acid,quercetin in the synthesis pathway of secondary metabolites were significantly correlated with DEGs genes such as POD,CCR,CAD,4CL,COMT and UDP glycosyltransferase;Abscisic acid,jasmonic acid and Zeatin,the marker metabolites in hormone and signal transduction pathway,were significantly correlated with multiple PP2 C,serine/ threonine protein kinase. |
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