Transcriptomic And Metabolomic Integrative Analysis To Identify Key Genes Invoved In The Regulation Castor Plant Height Development

Plant architecture is one of the important crop traits.The dwarf plant is suitable for dense planting and is resistant to lodging,which helps increase crop yields,save the labor force,and create higher economic value.Therefore,cultivating suitable crop height has become one of the key jobs for crop breeding.In recent years,the mining of dwarf-related genetic resources and the exploration of dwarfing mechanism exploration have attracted more and more attention.Castor,as one of the top ten oil crops in the world,in recent years,due to factors such as high plant height,low yield,and unfavorable mechanized harvesting,the planting area of castor has shown a sharp shrinking trend,which has restricted the development of related fields.Castor plant height is a quantitative trait regulated by multiple genes with a complex genetic basis and unclear regulatory mechanism.We used transcriptome and metabolome analysis to compare the development of high and dwarf castor stalks,identify candidate genes for plant height development,and analyze the molecular mechanism of castor plant architecture development.This thesis mainly consists of the following work:Castor transcriptome comparison was performed between high and dwarf cultivars using the sequencing data between 2 pairs of castor transcriptome raw datasets from the Castor Engineering Center of Inner Mongolia University for Nationalities.1862 differentially expressed genes were identified in W-DOF mutant group.3155 differentially expressed genes were identified in Zhezi2129 group.There were 458 common genes screened between the DEGs of W-DOF mutant group and Zhezi 2129 group.Differentially expressed genes were mainly enriched in starch and sucrose metabolic pathway,ribosome pathway,and photosynthesis pathway.A pair of high and dwarf castor internode tissues in the fast-growing period(8-10 leaf stage)were used as experimental materials to measure the plant height-related data.The internode length of the 3rd,4th,and5 th nodes showed significant differences in the 8-10 leaf stage.The width of the xylem and cortex of dwarf internode tissue were larger than those of the high-stalked castor plant significantly,while the cell length and the vessel number in the cortex were smaller than those of the high-stalked castor plant.Compared with the high-stalked castor,the internode tissue of the dwarf-stalked castor showed an earlier lignification state.The auxin content of the dwarf-stalked castor plant was significantly lower than that of the high castor plant.Auxin may be related to castor internodes elongation.Lignin and cellulose are the two main cell wall components.The lignin content is higher in the dwarf internodes,while the content of cellulose is higher in the high-stalk castor plant.This result is consistent with the cytological characteristics,which further proves that the dwarf castor bean cells have entered an earlier stop of elongation growth with a secondary wall lignification development state.The joint analysis of transcriptome and metabolome of internode tissues showed that differentially expressed genes and metabolites were significantly enriched in the phenylpropane biosynthesis pathway(lignin polymer synthesis),the plant hormone signal transduction pathway,especially the auxin signal transduction pathway,and Cell cycle,DNA replication and other pathways related to cell division,carbohydrate metabolism pathway,etc.Based on the comprehensive analysis of differentially expressed genes in internode tissues and castor resequencing genome in published literature,67 genes related to castor plant architecture development were screened.The polar transport of auxin promotes the elongation and growth of stem internode tissue,and has a negative regulatory effect on the lignification development of vascular tissue cell walls.In this study,we identified candidate genes related to castor stalk development by analyzing genome resequencing data,transcriptome data,and metabolome data combined with published genome data to reveal the molecular mechanism of castor plant architecture development regulated by auxin and cell wall lignification development.And we hope to provide a theoretical basis for the improvement of castor plant architecture.