| Sugarcane(Saccharum spp.hybrids)is the most important sugar crop and an important low-carbon economic crop.It is mainly distributed in Guangxi,Yunnan,Guangdong,Hainan and other provinces(autonomous regions),accounting for 92%of China's total sugar production.It plays an exceptional role in edible sugar safety in China.Mythirnna separata belongs to genus:Lepidoptera and family:Noctuidae,and it is harmful to 16 families and more than 300 species of plant including sugarcane.They feed on leaves which cause serious losses to corps.The outbreaks of armyworms in some sugarcane growing areas including Guangxi,Yunnan and Guizhou,resulted in middle stalk left,and has serious impact to local sugarcane yield.At present,the way to control armyworms are mainly by chemical control.The long-term use of chemical pesticides will lead to the improvement of pest resistance and environmental and ecological safety problem.Breeding and utilizing insect-resistant varieties is the most economical and effective method for controlling insects.The plant defense response caused by herbivorous insects provide valuable genetic resources for excavating plant endogenous insect-resistant genes,and for breeding insect-resistant varieties.Previous studies shows that exogenous spraying of methyl jasmonate(MeJA)can induce the activation of plant defense-related genes,through the production of defense substances and increase the level of plant defense.Furthermore,MeJA plays an important role in plant stress response,growth regulation and plant development.Therefore the aim of this study was to investigate the sugarcane gene expression level under insect treatment and MeJA spraying,and discover the sugarcane inner insect-resistance mechanism.Furthermore,our work will make contribution to utilize MeJA in selection of insect-resistance sugarcane.In the present study,we conducted experiment to spray methyl jasmonate(MeJA)or feed armyworm in sugarcane to study the response of endogenous gene relationship of transcription in sugarcane leaves between two stresses at different time points(0h,12 h and 24h).According to the transcriptome sequence,several important genes in the sugarcane jasmonic acid pathway were cloned,and qRT-PCR was used to confirm the relationship of these protein between armyworm feeding and MeJA stress.The results of this study aimed to explore the changes of sugarcane endogenous genes in response to armyworms feeding,and to elucidate the relationship between thefunction of sugarcane insect-resistant defense protein and MeJA stress.The main findings of this are as follows:1.From the RNAseq results of the armyworm feeding(Bite-12 h,Bite-24h),MeJA stress(MeJA-12 h,MeJA-24h)and control treatment(CK-0h),a total of112,788 differential expressed genes were obtained.Among them,the up-regulated genes in Bite-12 h Vs CK,Bite-24 h Vs CK,MeJA-12 h Vs CK and MeJA-24 h Vs CK,four groups were 9460,8780,7218 and 6955 genes,respectively.However the number of down-regulated genes were 4202,1768,7654 and 3186,respectively.2.According to the GO annotation,the effect of the armyworm feeding and MeJA stress treatment is similar on up-regulated gene expression pattern,while the expression level are different in down-regulated gene.The results of KEGG Pathway enrichment showed that there were a large number of differential gene enrichment in the phytohormone pathway,especially the jasmonic acid pathway,transcription factor pathway,and phenylpropanoid pathway.3.According to the results of transcriptome sequencing,the full-length sequences of six related genes(ScAOC,ScAOS,ScCOI1,ScCOI2,ScJMT and ScLOX)on the jasmonic acid(JA)pathway were successfully cloned and bioinformatics analysis were performed.The qRT-PCR analysis of these genes revealed that the expression fold change of these genes was consistent with the transcriptome data.ScAOS and ScLOX showed the same up-regulated trend under both stresses,while ScAOS was highly expressed under feeding stress. |
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