Study On The Physiological Changes And Molecular Mechanisms In Paeonia Lactiflora Pall Seeds During Dormancy Releasing

Paeonia lactiflora Pall is a versatile plant that can be used both as an ornamental and medicinal plant.Paeonia suffruticosa is the basal plant of Chinese herbal medicine Paeoniae Radix Rubra.The peony has a high economic value,But the seeds of peony have dormancy characteristics,which affects the reproduction of peony.Studies have shown that the germination of peony seeds requires warm temperatures to take root,the roots grow to a certain length,and buds grow at low temperatures.According to the previous research results of peony seed dormancy,the dormancy method of peony seeds was optimized,And the dormancy process of peony seeds was observed under the optimal treatment,determine the critical period of dormancy release,then perform physiological changes analysis combined with transcriptome differential gene expression analysis,to construct the dormancy release regulation network of peony seeds,the results provide a theoretical basis for further exploration of the dormancy release of peony seeds.The main research results are as follows:(1)The best treatment method for peony seed dormancy release is 20℃ warm sand storage,When the root grows to more than 4cm and is stored in low temperature sand at4℃,the emergence rate can reach 98%.The dormancy release process of Paeonia lactiflora seeds can be divided into hypocotyl growth under warm temperature,embryo expansion and epicotyl growth under low temperature.A total of 41204 differentially expressed genes were obtained during the release of seed dormancy.A total of 11045 genes were differentially expressed during the growth of peony seed hypocotyls,of which 4933 genes were up-regulated and 6112 genes were down-regulated.During the process of epicotyl dormancy release,4158 genes were up-regulated and 5884 genes were down-regulated.During the process of embryo enlargement and radicle elongation,the differentially expressed genes were the most,of which 22,672 genes were up-regulated and 10,985 genes were down-regulated.Trend analysis and kegg enrichment analysis showed that the differential genes during hypocotyl growth were mainly enriched in plant endogenous hormone transduction and glycolysis pathways.The differential genes in germ enlargement and radicle growth process were mainly enriched in plant endogenous hormone transduction,sugar and starch metabolism,fat metabolism,TCA cycle,and glycolysis pathway.Epicotyl growth differential genes were also mainly enriched in sugar and starch metabolism,fat metabolism,TCA cycle,and glycolysis pathways.(2)Substance metabolism regulates the dormancy release of Paeonia lactiflora seeds.The results showed that the storage material of peony seeds was mainly fat,and the fat content was about 28%.An overall decrease in fat,starch,protein and soluble sugars,Provide material basis for germination of peony seeds.Fat is the most energy-supplying material in the dormancy release of peony seeds.The changing trend of enzymes that break down nutrients is in line with the changes in nutrients.In addition,during the release of dormancy,the activity of antioxidant enzymes was enhanced.Transcriptome analysis of the key period of peony seed dormancy release,A total of 118 differentially expressed genes were identified in the fat and starch metabolism pathways.By combining physiological data and PCR for analysis,Five genes that play a major role in the dormancy release of peony seeds were screened out,namely GPAT,LACS,BAM,FRK,and AMY.(3)Plant hormones regulate seed dormancy,13 hormones were identified,which belonged to 7 categories of plant hormones,and all of them changed differently during the process of peony seed dormancy release.Abscisic acid,isoleucine jasmonate,cytokinins,and salicylic acid were all decreased overall.However,only jasmonate isoleucine,abscisic acid and cytokinins continued to decrease,The three may play a major inhibitory role in the release of dormancy.The levels of gibberellin,auxin and ACC were all elevated overall,which promoted the release of dormancy.Among them,ACC began to increase after dew white.Further analysis of the proportional changes of the 4 major hormones,GA/ABA,IAA/ABA and CTK/ABA decreased overall in the critical period of peony seed dormancy release.Proportional changes in hormone content may be the main reason for the release of dormancy.Transcriptome analysis of peony seeds during the critical period showed that,A total of 274 differential genes were identified in plant hormone synthesis and signal transduction pathways by combining metabolomic data and PCR analysis,Nine genes that play a major role in hormone regulation of peony seed dormancy release were screened out,including CYP707 A,NCED,KAO,YUCCA,IPT,GA2 ox,DELLA,PP2 C,and ACS.(4)In this study,a total of 1362 TFs were identified that were differentially expressed in the dormancy release of peony seeds.The TFs gene family with the most DEGs is C2H2,with a total of 151,accounting for 8% of all TFs differential genes,Followed by b HLH,ERF,MYB-related and so on.Among the identified transcription factor families,most genes in the ERF,WRKY,MYB,b HLH and b ZIP gene families were differentially expressed in the low temperature sand storage stage,It can provide a new research direction for the release of epicotyl dormancy in peony seeds.