Molecular Mechanism Of Ostrinia Furnacalis(guenée) In Response To UV Stress

Ostrinia furnacalis（Guenée）,an important pest of corn,has substantial detrimental effects on corn production.The moths of this nocturnal is a typical phototactic insect,which has strong phototaxis to ultraviolet light（UV）.In the present sutdy,we study the transcriptome and metabolome of O.furnacalis female adults under UV stress of different duration（0 h,1 h,2 h）,molecular cloning amd characterization of JNK and p38 and their expression patterns during UV light irradiation（0 min,30min,60 min,90 min,120 min）in O.furnacalis.The main results were summarized as follows:1.Transcriptome analysis of O.furnacalis female adult under UV stressAim to understand the transcriptome features of O.furnacalis,to enrich its transcriptome data,and to reveal the molecular mechanisms of O.furnacalis response to UV stress.The differences in transcriptome expression under different UV duration（0 h、1 h、2 h）of O.furnacalis were detected by high-throughput sequencing technology Illumina Hi Seq^TM2000.Results:We obtained three c DNA libraries,and all reads were assembled into 10 506 unigenes with an average length of 616 bp.A total of 157 and637 genes were differentially expressed in O.furnacalis after UV exposure 1 h and 2 h compared with the control,with 103 and 444 genes up-regulated,54 and 193 genes down-regulated,respectively.Besides,a total of 44 DEGs were detected in the UV2h group compared with UV1h,with 32 genes up-regulated and 12 genes down-regulated,respectively.The comparative transcriptome analysis between UV-treated and control revealed involvement of signal transduction,detoxification and stress-response,immune defense and antioxidative system.2.Metabolomic analysis of O.furnacalis female adult under UV stressDifferential metabolites of O.furnacalis under different during（0 h、1 h、2 h）UV stress were analyzed by liquid chromatography-mass spectrometry（LC-MS）.A total of181 differential metabolites（up:42,down:139）were identified in the UV1h group compared with the control under positive ion mode,and a total of 111 differential metabolites（up:46,down:65）were identified in the UV2h group compared with the control,and a total of 34 differential metabolites（up:28,down:6）were identified in the UV1h group compared with the UV1h.Besides,A total of 135 differential metabolites（up:32,down:103）were identified in the UV1h group compared with the control under positive ion mode,and a total of 93 differential metabolites（up:38,down:55）were identified in the UV2h group compared with the control,and a total of36 differential metabolites（up:31,down:5）were identified in the UV2h group compared with the UV1h.We used principal component analys is（PCA）and projections to latent structures-discriminant analys is（PLS-DA）to analyze 590 DEMs,and found there were significant differences between UV（1h,2h）group and the control.The DEMs were mainly involved in the metabolic pathways of sugar metabolism,lipid metabolism and amino acid metabolism,et al.3.Cloning and expression profile of OfJNK and its response to UV stress in O.furnacalisIn this study,a JNK gene was cloned from O.furnacalis,and named OfJNK（Gen Bank accession no.:MK779707）,which is 1 657 bp in length and contains an open reading frame（ORF）of 1 143 bp,encoding 381 amino acid residues.The putative protein is 44.34 k D with an isoelectric point（p I）of 6.06.The phylogenic tree indicated that OfJNK shares a high homology with JNK from other insect species.RT-q PCR results showed that OfJNK gene was expressed at all developmental stages（eggs,1-5instar larvae,pupae,3-day-female adults and male adults）,in various tissues（head,chest,abdomen,leg,wing,antennae,compound eye,midgut,and ovary）and under UV stress（0,30,60,90,and 120 min）.The expression levels of OfJNK was relatively higher in eggs than in other developmental stages.Moreover,OfJNK was specifically expressed in wing and antennae.The m RNA expression of OfJNK in female adults was induced by UV stress,increasing firstly and then decreasing with the increase of the exposure time,and reached the highest expression level at 60 min.The results indicate that UV radiation could induce the up-regulation of OfJNK expression in female adults of O.furnacalis,activate JNK signaling pathway in response to UV stress.In summary,our results will provide a foundation for additional research needed to determine the role of the JNK signaling pathway and the underlying mechanisms by which it shows resistance to environmental stresses in insects.4.Cloning and expression profile of Ofp38 and its response to UV stress in O.furnacalisIn this study,a p38 gene was cloned from O.furnacalis,and named Ofp38（Gen Bank accession no.:MK779707）,which is 1 657 bp in length and contains an open reading frame（ORF）of 1 080 bp,encoding 360 amino acid residues.The putative protein is 41.72 k D with an isoelectric point（p I）of 5.84.The phylogenic tree indicated that Ofp38 shares a high homology with p38 from other insect species.RT-q PCR results showed that Ofp38 gene was expressed at all developmental stages（eggs,1-5 instar larvae,pupae,3-day-female adults and male adults）,in various tissues（head,chest,abdomen,leg,wing,antennae,compound eye,midgut,and ovary）and under UV stress（0,30,60,90,and 120 min）.The expression levels of Ofp38 was relatively higher in female adults and eggs than in other developmental stages.Moreover,Ofp38 was specifically expressed in ovary,leg and midgut.The m RNA expression of Ofp38 in female adults was induced by UV stress,increasing firstly and then decreasing with the increase of the exposure time,and reached the highest expression level at 30 min.The results indicate that short-term UV radiation could activate the p38 signaling pathway in female adults of O.furnacalis in response to UV stress.Our study preliminarily elucidated the function of Ofp38 in response to UV stress in O.furnacalis.