MiRNAs Response To Drought Stress In Paulownia ’yuza 1’

Drought stress is an important external factor which can limit the geographic distribution and impede growth and reproduction of plants.Seriously,plants will be died under drought condition.Paulownia is a primary afforestation tree species in China.Plantation of Paulownia on a large scale has important roles in creating a nice ecological environment and improving farmers’ living standard.So far,little research focused on micro RNAs(miRNAs)response to drought stress of Paulownia had been reported.It is of great theoretical significance and application value to research miRNAs response to drought stress of Paulownia against the background of transcriptome,which can reveal the molecular mechanism responsive to drought in Paulownia and popularize this plant repre.Using the high-throughput sequencing technology,a total of 107 miRNAs(32conserved miRNAs and 75 novel miRNAs)were identified in Paulownia tomentosa×Paulownia fortunei(Paulownia ‘yuza 1’).Totally,77 differential expression miRNAs(60 were in down-regulation and 17 in up-regulation)were found.Among these 77 miRNAs,60 significantly differentially expressed(44 were in down-regulation and 16 in up-regulation).Through the degradome approach,42 target genes were predicted.Subsequently,Gene Ontology and Kyoto Encyclopedia of Genes and Genomes databases were employed to analyze the functional classification and metabolic pathways of predicted target genes.Results of Gene Ontology showed that functions of the putative target genes mainly embodied in cell,cellular process,cell part and metabolic process.After analyzing the data of Kyoto Encyclopedia of Genes and Genomes,we found that these target genes were involved in biosynthesis of secondary metabolites,plant hormone signal transduction,ABC transporters,photosynthesis,diterpenoid biosynthesis,base excision repair,plant-pathogen interaction,spliceosome,m RNA surveillance pathway,pyrimidine metabolism,amino sugar and nucleotide sugar metabolism,glycine,serine and threonine metabolism and non-homologous end-joining metabolic pathways.Then the predicted target genes were matched to Nr database for functional annotations.Results indicated that some target genes response to drought stress via plant hormone signaltransduction,photosynthesis and osmotic adjustment.Hence,we speculated that some differential expression miRNAs took part in resisting drought stress in Paulownia‘yuza 1’.Moreover,the quantitative real-time PCR(q RT-PCR)verification results of seven miRNAs which selected at random were consistent with that from high-throughput sequencing.While the q RT-PCR verification results of target genes assumed negative regulation with their corresponding miRNAs.In a word,our results can provide reference to reveal the molecular mechanism of Paulownia ’yuza 1’ in response to drought.