Transcriptomic And Metabolomics Study Of The Early Interactions Between Siraitia Grosvenorii Roots And Meloidogyne Incognita

Siraitia Grosvenorii is a dioecious economic plant for both medicinal and edible purposes.It mainly grows in northern Guangxi.When it cropped,the plant was infected by the Meloidogyne incognita extremely easily.This will lead to the plant yield reduction,and even plant death.Therefore,it is of great theoretical and practical significance to explore the mechanism of interaction between Siraitia grosvenorii and M.incognita,and to seek for the prevention and control of M.incognita.In this study,we used the transcriptomic and metabolomics techniques to research the roots of Siraitia grosvenorii which infected by M.incognita at different time points.The platform for transcriptome sequencing is Illumina HiSeq.And we analyze the datas in several ways,such as GO functional annotation,KEGG pathway annotation and differentially expressed genes between different groups and so on.Our aim is to find out the differentially expressed genes with high correlation in the influence of M.incognita.At the same time,LC-MS non-targeted metabonomics technique was also used to investigate the changes of the root system of Siraitia grosvenorii at the metabolomic level after being infected by M.incognita.The molecular mechanism of interaction between Siraitia grosvenorii and M.incognita was discussed from the perspective of transcriptome and metabolome,which provided theoretical basis for molecular breeding of resistance to root-knot nematode in Siraitia grosvenorii.The main results are as follows:1.By observing the development of root knot nematode in Siraitia grosvenorii at different stages after inoculation,the results showed that the root morphology of Siraitia Grosvenorii was changed about 4 days after inoculation by nematodes.2.Through transcriptome sequencing of root samples of Siraitia grosvenorii after infected by M.incognita,5252 Unigenes were annotated in NR,GO,KEGG,eggNOG,Swiss-Prot databases.All of them are commented on by function.Through Statistical analysis of differentially expressed genes,the number of up-regulated and down-regulated genes in Siraitia grosvenorii seedlings after inoculated 7 days,the number of differentially expressed genes is at most.According to the analysis of KEGG metabolic pathway,the differential genes are mainly concentrated in plant hormone transduction pathway,plant-pathogen interaction pathway,phenylpropane biosynthesis,flavonoid biosynthesis,carbohydrate metabolism,P53 signal pathway,fatty acid metabolism and alkaloid biosynthesis.It was found that the differentially expressed genes were mostly related to the synthesis of hormones such as ethylene,abscisic acid,auxin and jasmonic acid,as well as transcription factors such as AP2/ERF,WRKY,MYB,disease-related proteins and secondary metabolites such as peroxidase,catalase,tyrosine ammonia lyase are related.These genes may play an important role in the infection of M.incognita.3.In order to verify the accuracy of transcriptome sequencing results and the expression of genes related to the interaction mechanism,14 genes were selected from different genes for RT-PCR verification.The results showed that the sequencing results were real and reliable.4.Based on LC-MS metabonomics method,the species and content changes of metabolites in Siraitia grosvenorii infected with M.incognita for 7 days were studied.PCA,PLS-DA,OPLS-DA multivariate statistical methods and T-test univariate statistical methods were used to classify and identify potential markers.The results showed that the metabolites in roots of Siraitia grosvenorii seedlings changed significantly at 7 days post-inoculation compared with before inoculation.The ion peaks of metabolites were extracted by XCMS software.There were 17843 positive ion peaks and 10799 negative ion peaks.There were 226 qualitative metabolites,144 positive metabolites and 82 negative metabolites.By comparing the change trend of Siraitia grosvenorii after 7 days and before inoculation,12 most significant metabolites were found.The accumulated metabolites were Betaine,3-Hydroxycapric acid,Nicotinamide,Diethanolamine,Palmiticacid,Phosphoethanolamine.The Decreased metabolites were Phe-Tyr,Rosmarinic Acid,Sucrose,alpha,alpha-Trehalose,Myristic acid.Betaine and trehalose play an important role in plant biological stress,they participate in the metabolic pathway of plant response to biological stress.They are produced in large quantities at 7 days post-inoculation,and may participate in the disease resistance of Siraitia grosvenorii seedling to M.incognita.Enrichment analysis of KEGG metabolic pathway of differential metabolites revealed that differential metabolites were mainly concentrated in Cutin,suberine and wax biosynthesis and ABC transporter pathway.