| Elymus sibiricus is a type species of Elymus genus of Poaceae.It has excellent characteristics such as strong cold resistance,wide adaptability and good palatability.It is widely used in grassland vegetation restoration and artificial grassland construction in Qinghai-Tibet Plateau.However,the actual seed yield of E.sibiricus is difficult to meet the production needs due to its strong shattering property.Brassinolide has the functions of increasing plant yield,improving crop quality and inhibiting organ shedding,but its effect and regulation mechanism on shattering of E.sibiricus are still unclear.In this study,Zh N03,a new strain of E.sibiricus,was treated with exogenous brassinolide spraying treatment and the effects on seed phenotype and endogenous hormones were analyzed.Based on transcriptomic and proteomics techniques,the molecular regulation mechanism of seed shattering of E.sibiricus under exogenous brassinolide treatment was explored.The effects of exogenous brassinolide treatment on the shattering of E.sibiricus were revealed from the anatomical,physiological and biochemical,transcriptomic and proteomic levels.The main test results are as follows:1.The study on the phenotypic characteristics,cell structure and physiological indexes of the seeds and abscission zones of E.sibiricus treated with three different concentrations of brassinolide showed that the treatment of 0.01 mg/L and 0.1 mg/L brassinolide solution significantly increased the value of breaking tensile strength,and decreased the shattering rate;0.005 mg/L brassinolide solution treatment increased the awn length and thousand-grain weight of E.sibiricu seeds.The results showed that the fracture surface of abscission zone was not a complete plane structure,but a layered depression.In the control group,the surface of abscission layer was smooth and the cell contour was fuzzy,the abscission layer was degraded.Treatment with exogenous brassinolide significantly increased the contents of endogenous gibberellin,auxin,abscisic acid,ethylene and lignin,and increased the activities of cellulase and polygalacturonase in the seeds.2.Transcriptome sequencing analysis was performed on abscission zones of E.sibiricus treated with brassinolide at different concentrations for 24 h,141,964 transcripts were obtained,of which 137,358 transcripts were annotated.881,2830 and1153 differentially expressed transcripts were obtained in three treatment groups,respectively.The functional annotation of differentially expressed transcripts indicated that the differentially expressed genes involved in plant hormone signal transduction,lignin biosynthesis and metabolism,and hydrolase synthesis might be the main reasons for the differences in seed shattering among different treated materials.Core genes such as BEL1 transcription factor,COBRA,Ces A and POX were screened by weighted gene co-expression analysis,and these genes may play an important role in regulating the seed shattering process of E.sibiricus.3.Proteomics technology was used to analyze the abscission zones of E.sibiricus,and a total of 392 differential proteins were obtained.GO and KEGG analysis of differentially expressed proteins in different treatment groups found that there are 3,24 and 8 differentially expressed proteins associated with seed shattering function under brassinolide induction.Further analysis showed that exogenous brassinolide treatment positively regulated proteins related to the biosynthesis of phenylalanine and the formation of monomeric lignin,and increased the concentration of endogenous lignin in E.sibiricus seeds,thereby reducing the seed shattering rate.4.The transcriptomic and proteomic analysis showed that there were 15,97 and9 protein-m RNA associates in different treatments,respectively.Based on GO and KEGG analysis,it was found that the correlated genes and proteins with consistent and significantly up-regulated expression trends were mainly concentrated in “protein processing in the endoplasmic reticulum”,“oxidative phosphorylation”,and other cellular life processes.In particular,brassinosteroid treatment promoted the accumulation of genes and proteins related to phenylpropane biosynthesis,and increased the concentration of endogenous lignin in the seeds of E.sibiricus,which may have a positive effect on reducing seed shattering. |
