Comprehensive transcriptome analysis of grafting onto Artemisia scoparia to affect the aphid resistance of chrysanthemum (Chrysanthemum morifolium)

Aphid stress drastically influences the yield and quality of chrysanthemum, and thus grafting has been widely used to improve tolerance to biotic and abiotic stresses. But how grafting affects chrysanthemum resistance to aphid the mechanism remains unclear. Therefore, we used the RNA-Seq platform to perform a de novo transcriptome assembly to analyze the selfrooted grafted chrysanthemum (Chrysanthemum morifolium Ramat. 'Hangbaiju') and the grafted Artermisia-chrysanthemum (grafting onto Artemisia scoparia) transcription response to aphid stress. The results showed that there were 1337 differently expressed genes (DEGs), among which 680 were up-regulated, and 667 were down-regulated in Cm/As in comparison to Cm/Cm. These genes were mainly involved in glycometabolism, biosynthesis of secondary metabolites, phytohormone signaling and plant-to-pathogen pathway, and so on. KEGG and GO enrichment analysis revealed the coordinated up-regulation of these genes from numerous functional categories related to aphid stress responses. In addition, we performed the determination of physiological indicators of chrysanthemum treated under aphid stress, and the results were basically consistent with molecular sequencing results. All evidence indicated that grafting onto Artemisia scoparia upregulated aphid stress responses in chrysanthemum. In summary, our study presents a genome-wide transcript profile of the selfrooted grafted chrysanthemum and the grafted Artermisia-chrysanthemum and provides insights into the molecular mechanisms of C.morifolium in response to aphid infestation. These data contributes to our deeper relevant researches on aphid tolerance and further exploring new candidate genes for chrysanthemum molecular breeding.