Effects Of Exogenous SRNA On The Growth And Development Of Arabidopsis Thaliana And Its Absorption Mechanism

Regulatory small RNAs(sRNAs)are ubiquitous in eukaryotes,which recognize the sequence by complementary pairing to specifically regulate target gene expression.As the most important ones,microRNAs(miRNAs)are involved in extensive physiological processes in animals and plants including immune response,organ morphogenesis,nutrient metabolism,and stress resistance.More and more evidence show that miRNAs not only play a role in the initial cells,but also can be transported in vivo,even across species to regulate gene expression.As the vast majority of plants are sessile and lack of escape mechanism during life history,they are More susceptible to environmental impact.At present,there are many reports on the cross-kingdom regulation of miRNAs between plants and the associated organisms.However,little is known about the effects of exogenous microRNAs on plant growth and development.In present study,I used the model plant,Arabidopsis as material to investigate the effects of animal-derived sRNAs on plant grown and the possible absorption mechanism.First,the expression of GFP was inhibited by exogenous supplied of small silencing RNAs(siRNAs)against GFP,indicating that the exogenous sRNAs are functional in Arabidopsis.The Arabidopsis seedlings grown on farmyard manure,which are predicted abundant of animal miRNAs,showed the lag of bolting time and longer growth period compared to those on regular culture soil.The small RNA deep sequencing revealed that a large number of exogenous animal miRNAs existed in Arabidopsis seedlings and the shared miRNAs accounted for a large proportion,inferring that the exogenous miRNAs absorbed by plants are universal.Moreover,the phenotype of Arabidopsis overexpressing miR184-3p resembled that of plants grown on fermented farmyard soil,including the lagging bolting,longer growth period and larger rosette leaves.Meanwhile,spraying synthetic siR184-3p duplex on Arabidopsis seedlings also showed a similar phenomenon of delay in bolting.Though transcriptome analysis of overexpressing miR184-3p,it was found that many genes controlling bolting and flowering(such as AP1 and SPL9)were down-regulated.On the other hand,the absorption and transport of exogenous sRNA in plant were also assessed via Carboxyfluorescein-labelling(FAM-labeled).Compared to exogenous double-stranded sRNA(dsRNA),plants are more readily to absorb exogenous single-stranded sRNA(ssRNA).The exogenous ssRNA could stably present for more than 8 days without being methylated in plants.Further,the further analysis revealed that the absorption of exogenous sRNAs by Arabidopsis were length and sequence-dependent,and the long RNA precursor with hairpin structure could be further processed into short ssRNA in plant cells.Overall,the current work used a variety of experimental techniques to demonstrate the absorption of exogenous miRNAs in Arabidopsis thaliana and the effect of miR184-3p on the growth and development of Arabidopsis thaliana.These results provide a basis for understanding the role of exogenous sRNA as a regulator of plant growth and development and as a medium for information exchange with the related species.