Maize is one of the most important cereal crops worldwide and one of the primary targets of genetic manipulation,which provides an excellent way to promote its production.However,the obvious difference of the dedifferentiation frequency of immature maize embryo among various genotypes indicates that its genetic transformation is dependence on genotype and immature embryo-derived undifferentiated cells.To identify important genes and metabolic pathways involved in forming of embryo-derived embryonic calli,in this study,DGE (differential gene expression) analysis was performed on stages Ⅰ,Ⅱ,and Ⅲ of maize inbred line 18-599R and corresponding control during the process of immature embryo dedifferentiation.A total of ~21 million mDNA tags were sequenced,and 4,849,453,5,076,030,4,931,339,and 5,130,573 clean tags were obtained in the libraries of the samples and the control,respectively.In comparison with the control,251,324 and 313 differentially expressed genes (DEGs) were identified in the three stages with more than five folds,respectively.Interestingly,it is revealed that all the DEGs are related to metabolism,cellular process,and signaling and information storage and processing functions.Particularly,the genes involved in amino acid and carbohydrate transport and metabolism,cell wail/membrane/envelope biogenesis and signal transduction mechanism have been significantly changed during the dedifferentiation.To our best knowledge,this study is the first genome-wide effort to investigate the transcriptional changes in dedifferentiation immature maize embryos and the identified DEGs can serve as a basis for further functional characterization.