The Impact Of Wheat Allopolyploidization On Transcriptomes In Early Developing Seeds

Wheat(Triticum aestivum L.)is not only one of the most important food crops in the world,but also an ideal model for studying the inheritance and evolution of allopolyploids.Given to the relatively clear evolutionary process of wheat,artificially synthesized wheat can be created by simulating the wheat synthesis process in the laboratory.Synthetic wheat often has excellent agronomic traits.The comprehensive systematic analysis of the subgenomic gene expression changes and gene interactions during the synthesis process helps to elucidate the mechanisms of polyploid synthesis and evolutionary,and to explore the important genes with respect to excellent phenotypes.Transcriptome sequencing is an important tool for studying changes in genome-wide gene expression during polyploidization,but sequencing of a single stage is difficult to interpret complex biological processes.Time-series transcriptome sequencing utilizes sequencing data at multiple time points in a row,and the complete developmental process can be systematically studied through clustering and co-expression of network analysis.In order to study the intrinsic molecular mechanism of excellent phenotypes,this study used time-series transcriptome sequencing for the early developmental stages(0,2,4,6,8,10 DAP,days after pollination)of two sets of synthetic wheat and cultivar Chinese Spring seeds to construct of early development co-expression network of grain.1.In this study,108 samples were subjected to high-quality deep transcriptome sequencing,and a total of1.70 Tb of high-quality data was obtained.It was found that the development process of different ploidy wheat was conserved.According to the correlation of time-series gene expression,the number of differentially expressed gene and functional enrichment difference,the early development can be divided into two different stages,rapid cell division and differentiation stage(0-4 DAP)and nutrient accumulation stage(8-10 DAP),and 6 DAP as a two-stage transition period.2.The correlation analysis of the time series expression of two sets of hexaploid synthetic wheat genes showed that the gene expression correlation between the progeny and parental subgenome A and B was significantly higher than that of subgenome D during the synthesis process of hexaploid.The expression of conserved genes tends to be highly expressed in the first stage,and is enriched in basic life activities such as DNA replication and cell cycle,while the expression of diverged genes is consistent,with no obvious characteristics,and is significantly enriched in post-transcriptional regulation such as RNA methylation and RNA cleavage or heat shock response such as protein folding.3.The results of additively and non-additively expressed gene analysis of synthetic wheat and parents showed that the number of additively expressed genes accounted for the majority of the expressed genes,and nonadditive synthesis only accounted for 0.8-2.96%.Important genes found in non-additively expressed genes,such as starch synthesis,cell wall cellulose synthesis,cell expansion and sugar transport,may be related to endosperm cellularization,expansion of endosperm cell size,and early grain filling.4.Analysis of dominant expression genes in synthetic wheat and parents revealed that the number of maternal dominant expression genes was the highest,accounting for 60-80% of the total number of dominant genes,and the paternal dominant expression genes accounted for 10-20% of the total.Comparing the maternal dominant high expression gene with the paternal dominant high expression gene,it was found that the maternal dominant high expression gene contains more genes related to DNA replication,and the paternal dominant high expression gene contains more genes related to stress response.The early co-expression network of grain development was constructed by using the weight co-expression analysis network method(WGCNA).Several important genes and co-expression networks related to grain size and grain weight were found.There was different expression patterns of cell cyle genes for different grain size of different ploidy wheat.