Circular RNA In Wheat Leaves Under Drought Stress:Genome-wide Identification Via High-throughput Sequencing And Preliminary Functional Prediction

Wheat(Triticum aestivum)in the normal growth process,often affected by drought stress.The Long non-coding RNA(lnc RNA)played an important role in the adaptive responses of drought stress in wheat,directly or indirectly.Circular RNA(circRNA)were a type of non-coding RNA with a closed-loop structure and without5'-cap and 3'-poly(A)tail which has been recognised through high-throughput deep sequencing.In animals and plants,circRNA acted as mi RNA sponges to competitively terminate suppression of their m RNA targets.However,there is no report about the circRNA of wheat took part in the drought stress response.To explore the quantity and their potential functions of circRNA in wheat seedlings while regulation of drought response,we extracted the total RNA from leaves of wheat seedlings(Triticum aestivum L.cv.Aikang58)under drought-stressed and well-watered conditions respectively.Then,genome-widely identified circRNA in wheat seedlings using high-throughput sequencing technology.Moreover,the sponge effect of differentially expressed circRNA and related m RNA were further predicted and discussed using bioinformatics tools combined with q RT-PCR validation,thus further reveals that circRNA regulatory impact of circRNA-mi RNA-gene.The main results were as follows:The content of relative water content(RWC)in wheat seedlings decreased and the content of malondialdehyde(MDA)and H2O2 increased after wheat seedling leaves treatment was carried out using PEG-simulated drought condition.The contents of superoxide dismutase(SOD),catalase(CAT)and peroxidase(POD)in wheat seedling leaves were all increased in order to reduce the damage caused by drought.Then,the circRNA enriched library based deep sequencing was performed and the circRNA were identified using bioinformatics tools.Around 88 circRNA candidates were isolated in wheat seedlings leaves while 62 were differentially expressed in drought expressed leaves compared to well-watered control.Among the dehydration responsive circRNA,six were found to act as 26 corresponding mi RNA sponges in wheat.The six circRNA were further validated to be circular by q RT-PCR assay,and five displayed consistencies in regulation with the transcriptome sequencing results.After Gene Ontology(GO)and Kyoto Encyclopedia of Genes and Genomes(KEGG)pathway analysis of the targeted m RNA functions,the circRNA were predicted to be involved in dehydration responsive process,such as photosynthesis,porphyrin and chlorophyll metabolism,oxidative phosphorylation,amino acid biosynthesis and metabolism,as well as plant hormone signal transduction,involving auxin,brassinosteroid,and salicylic acid.Herein,we revealed a possible connection between the regulations of circRNA with the expressions of functional genes in wheat leaves associated with drought resistance.