The Function Of MicroRNA858a In Regulation Of Arabidopsis Thaliana Photomorphogenesis

Photomorphogenesis is both a developmental process and a response to environmental stimuli,in which complicated gene regulation is involved.Although light-modulated alteration in transcriptomes has been well documented in photomorphogenic Arabidopsis,most efforts have focused on the transcriptional activation or repression of light-regulated genes.Posttranscriptional regulation of gene expression in the process of phomorphogenesis has been less studied.HY5 is a kind of main regulating factors that control the target gene locate in middle and downstream of the light regulation network.Recent reports revealed that small regulatory RNAs may participate in modulating the transcriptome shift duringphotomorphogen-esis.The task is designed to explore actions of small regulatory RNA atposttranscriptionallevel in photomorphogenic Arabidopsis.We will particular focus on micro RNA858 a which are directly regulated by HY5 at the seedling stage.Firstly,organ-specific expression patterns will be characterized for miRNA858 a.Identification of miR858 a transcriptional units and upstream promoter regions through RACE,build the promoter vector drive GUS report gene expression inplant.The results of staining analysis showed thatthe hypocotyls?the leaf vein of cotyledon,and lobus cardiacus of the seedlings under the lightconditions,the cotyledons ofthe seedlings under the dark conditions,the silique ? leaf vein ? the petiole and the anthers of the Arabidopsis thalianacan be clearly observed GUS staining.Real-time PCR were used to detect the miR858 a specific expression in different tissue under different light conditions,The detection results showed that the expression level of miR858 a in the siliqueof wild type Arabidopsis was significantly higher than that in other parts.Real-time PCR results showed that expression level of miR858 a in Arabidopsis was significantly higher than that in hy5,and the expression of miR858 a in the light condition was significantly higher than that in dark condition.Light response treatment of Arabidopsis thaliana showed that the Arabidopsis thaliana grown in darkness increased sharply with the accumulation of illumination time,and gradually became stable after reaching the peak at about 0.5 hour.These results suggest that miRNA858 a all stages have been expressed in plants,and has obvious light regulation function in photomorphogenesis.Then,we excessive expression miRNA858 a in the hy5 and wild-type Arabidopsis thaliana respectively.Overexpression of miRNA858 a in hy5,T3 generation homozygous strain showed relative to the reference strains hypocotyl shorten,anthocyanin and chlorophyll content were increased.At the same time,we transferred to the constructed artificial miRNA858 a expression vector in wild-type Arabidopsis thalianain.T3 generation homozygous strain of anthocyanin content is slightly decreased compared with control group,no obvious external phenotypic changes.Finally,by transcriptome sequencing comparisons will be used to identify differentially expressed genes among wild type,hy5,and transgenic plants with overaccumulation or repression of representative miRNAs,of which the related metabolic pathways will also be analyzed.Results from this study will be of substantial significance for exploration of the regulatory mechanism underlying photomorphogenesis at the posttranscriptional level,and also provide the theoretical reference for the use of miRNA858 a for crop improvement.