To investigate the mechanism in interaction between rust fungus and Picea crassifolia,this study utilized Illumina sequencing to sequence the transcriptome of healthy and diseased plants of Picea crassifolia.A total of 15,408 differentially expressed genes were obtained,with 10,296 genes up-regulated and 5,112 genes down-regulated based on a criterion of difference fold(FC)≥2 and false discovery rate(FDR)<0.01.In the GO annotation,the differentially expressed genes were significantly enriched in metabolic processes,cellular processes,catalytic activity,and binding.In the KEGG annotation,the differentially expressed genes were significantly enriched in ribosomes,plant-pathogen interactions,endoplasmic reticulum protein processing,and signal transduction.It is possible that the molecular mechanism of Picea crassifolia in response to rust infestation is regulated by a multigene network system,which induces multiple disease resistance pathways in Picea crassifolia.To validate the reliability of the RNA-seq data,RT-qPCR expression assays were conducted for 10 differentially expressed genes,and the results showed that the gene expression trends measured by RT-qPCR and RNA-seq were consistent.It helps us to investigate the role of candidate genes in the response of Picea crassifolia to rust infestation in-depth,and also lay the foundation for conducting functional genomics studies on disease resistance in Picea crassifolia.