Study On AtR18 Non-coding RNA Transcribed By RNA Polymerase ? In Arabidopsis Thaliana

Non-coding RNA refers to RNA which does not encode protein in the genome of an organism.It was once considered to be "gene garbage" which is unrelated to gene expression.Studies have shown that most plant genomes are transcribed into non-coding RNAs.They combine with protein molecules to turn genes on or off at the level of transcription,post-transcription and translation,to achieve the key role of regulating the expression of target genes,affecting plant germination and pollen.Its formation,metabolism and other phy-siological processes respond to various biological and abiotic stresses.AtR18 ncRNA(151nt)is a non-coding RNA transcribed by RNA Polymerase ? which was found in Arabidopsis in 2012,that has not been reported yet.The AtR18 ncRNA in Arabidopsis was studied and the results were as follows:1.Northern blot and overall in situ hybridization method showed that,AtR18 ncRNA was expressed in Arabidopsis seeds at the germination stage and protruded from the tip of the hypocotyl.It also provided that AtR18 ncRNA responded to a variety of stress environments such as ABA and Mannitol.2.Construction of AtR18 ncRNA overexpressing Arabidopsis plants.Under the con-ditions of ABA and Mannitol stress,statisticsed the germination rate of wild type Arabidopsis(Wt)and AtR18 ncRNA overexpressing Arabidopsis(AtR18-1#,AtR18-3#)seeds.As found that,AtR18 ncRNA overexpression increased the susceptibility of Arabidopsis seeds to ABA stress and decreased the susceptibility to drought stress.3.Analyzed the AtMYC1 gene,that flanked the AtR18 ncRNA 3' end.The results showed that AtMYC1 gene was abundantly expressed during seed germination.It also responded to ABA and Mannitol stress environments.Under the conditions of ABA and Mannitol stress,statisticsed the germination rate of wild type Arabidopsis(Wt)and atmycl deletion mutant Arabidopsis(salk-15,cs-5)seeds.As found that,the atmycl deletion mutant increased the sensitivity of Arabidopsis seeds to ABA stress and decreased the sensitivity to drought stress.4.AtR18 ncRNA has possibilities to inhibit seed germination,AtMYCl gene may induce seed germination.AtMYC1 gene responds to ABA stress by affecting the expression of SnRK2.2,ABI3,EM1,EM6 and other important genes in ABA signaling pathway.It is still not clear of the detailed mechanism action of AtR18 ncRNA in response to ABA and drought stress.Whether AtR18 ncRNA have transcriptional interference effects is also not clear and need to be studied.