Transcriptome And MiRNA Regulation Network Analysis Of Inflorescence Development In Barley

The shape of an inflorescence varies among cereals,ranging from highly branched in rice,termed a panicle,to a much more compact spike in barley(Hordeum vulgare)and wheat(Triticum spp.).However,little is known about the molecular basis specifying cereal inflorescence architecture,particularly for barley and wheat.In this study,we conducted transcriptome profiles at three meristem stages of the barley main shoot apex(MSA): spikelet initiation,floral organ differentiation and floral organ growth in comparison with that of vegetative tissue seedling.The major findings of this dissertation were listed as follows:1.We observed the potential key regulators with the dynamic expression and phasespecific accumulation patterns during the three reproductive stages.Co-expression assembly and Gene Ontology analysis identified 4,888 transcription-related genes such as transcription factors,histone modification and cell cycle progressions during the early inflorescence development,and genes’ relative-to-active photosynthetic and metabolic activities during floral organ growth.We also observed the differentially fluctuant expression patterns of VRS(SIX-ROWED SPIKE)genes and hormones auxin,gibberellic acid and cytokinin biosynthetic genes between two-rowed and six-rowed barley,during inflorescence development.2.By the small RNA sequencing data in the important stage of barley inflorescence development,combined with the degradome and RNA-seq data,using bioinformatics technology,we identified 109 known barley miRNAs and 870 novel miRNAs.Organ development-associated miRNAs(miR159,miR166,etc.)are highly expressed in barley inflorescences,and their target genes are expressed in barley development in a manner opposite to miRNAs,suggesting that miRNA-mediated regulation may be conserved between barley and other crops.Cluster analysis of 109 known miRNAs and870 new miRNAs revealed that the vast majority of miRNAs were phase-specific and preferentially expressed at a certain stage.Functional enrichment analysis of target genes indicates that it is mainly involved in anther development,hormone response and growth.Analysis of the regulatory network of miRNAs and their target genes revealed the regulatory range of miRNAs during barley inflorescence development.Collectively,this work reveals barley inflorescence phase-specific expression miRNAs and genes,and we propose a regulatory network controlling barley MSAs activities and flower development,providing an informative source for further uncovering the molecular mechanism of spike development.