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Regulation Of MicroRNA408 In Arabidopsis Growth And Development

Posted on:2020-03-10Degree:MasterType:Thesis
Country:ChinaCandidate:Z Q SongFull Text:PDF
GTID:2480305771982839Subject:Cell biology
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MicroRNAs(miRNAs)are the 19-24 nucleotides endogenous non-coding small RNAs.They emerging as gene repressors by directing the cleavage or translational repression of the target transcripts in the plant.As an endogenous regulator,miRNA plays an important role in the growth and development of plants and in biotic or abiotic stresses.MicroR408(miR408)is a highly conserved miRNA in terrestrial plants,implying that its function is fundamental to plants.Overexpression of miR408 can significantly promote vegetative growth of Arabidopsis plants.The transgenic Arabidopsis thaliana,which inhibits the expression of miR408,exhibits phenotypes such as abnormal inflorescence development and reduced seed set rate.Whether miR408 is involved in the process of plant reproductive growth is not clear.In the vegetative growth phase,miR408 overexpressing line(MIR408-OX)had obvious growth advantages,and the biological yield and seed yield were significantly increased,compared with the wild type.Cell biology statistics indicate that the increase in MIR408-OX cells size due to cell expansion rather than significant difference in total cell number.In the MIR408-OX transgenic Arabidopsis seedlings,the expression levels of key genes,for cytoplasmic flow,myosin XI and gibberellin(GA)synthase were significantly increased.miR408 is a key factor regulating the content of Copper,and repress several genes encoding for copper binding proteins with non-photosynthetic usage.Overexpression of miR408 inhibits the content of non-photosynthetic copper ion-binding protein,while the transcription level of copper ion transporter PPA1 increases significantly,promotes the transfer of cytoplasmic copper ions to chloroplasts,and increases the accumulation of plastocyanin(PC),resulting in a significant increase in the photosynthesis efficiency of transgenic plants.Transcriptome sequencing data indicate that overexpression of miR408 can directly or indirectly affect a variety of physiological and biochemical metabolic pathways,affecting plant growth and development.Overexpress two downstream target genes of miR408,plantacyanin(ARPN)and Laccase13(LAC13)result in the biological yield and seed yield of the transgenic Arabidopsis thaliana were significantly reduced,which is similar to the phenotype of the miR408 transgenic silencing strain(amiR408).By verifying the promoter activity assay,it was found that a potential open reading frame encoding the polypeptide was present in pri-miR408,which was named miPEP408.Subcellular localization demonstrates that miPEP408 may function in the cytoplasm and nucleus.miR408 and miPEP408 alone overexpressed and co-overexpressed lines,showing a more obvious growth advantage than wild type.The molecular mechanisms involved in the growth and development of miR408 and miPEP408 still need to be further studied.The root location of the transgenic plant pMIR408+ORF1.1+eGFP confirmed this result.At present,we have gotten transgenic plants that miR408 and miPEP408 overexpressed alone and co-overexpressed,respectively.The molecular mechanism of miR408 and miPEP408 involved in plant growth and development will be further explored.In summary,overexpression of miR408 significantly promoted vegetative growth and increased plant biomass and seed yield in Arabidopsis thaliana.In addition,miR408 is capable of encoding a functional polypeptide through a potential reading frame.However,its biological function still needs further research.
Keywords/Search Tags:miR408, biomass, seed yield, photosynthesis, Arabidopsis, growth advantages, miPEP
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