| MADS family proteins are kinds of important transcription factors which originally contained MCM1, AGAMOU, DEFICIENS and SRF protein with a highly conserved sequence that known as the MADS-box. MADS family proteins combined with specific DNA sequences by their conserved sequences in the form of dimer to regulate the gene expression. So far, hundreds of MADS-box family proteins and their target genes were characterized and identified in plants which involved in the regulation of plant growth and development, such as vegetative organgensis, the formation of flowers organ, seed development, and so on. However, the roles the MADS-box genes played in plant dedifferentiation hasn't been reported.In order to study the differences between mature and immature wheat embryos in dedifferentiation, the expressions of MADS-box related genes were analysized at transcription level with a Affymetrix wheat Gene Chip to reveal the possible role of MADS family genes during dedifferentiation of mature and immature wheat embryos. The results were as follows:The gene expressions of different time points ( ie, 2, 6, 12, 24, and 72h ) in dedifferentiation of mature and immature wheat embryos were studied. The 0 hours'sample was used as a contral and the genes which exhibited a greater than two folds change in gene expression level were considered as meaningful different expression genes. There were 81 and 95 MADS-related genes that were detected during dedifferentiation of mature and immature wheat embryos, respectively. Among them, 21 genes up-regulation, 50 genes down-regulation, and 10 up-and down-regulation in dedifferentiation of mature wheat embryos, and 13 genes up-regulation, 66 genes down-regulation, and 16 up-and down-regulation in dedifferentiation of immature wheat embryos, respectively. Majority of MADS family genes related to floral meristem and floral organs were down-regulated in wheat embryos dedifferentiation. The number of MADS family genes related to root growth, vernalization and embryonic growth were up-regulated in mature wheat embryos, but they were down-regulated in immature embryos. The number of genes related to leaves growth, response of surrounding signal, anthesis time were down-regulated during whole process or at some point of dedifferentiation of mature and immature wheat embryos. Besides, there were two MADS-box genes (m7, cdm51) detected whose function have not been known. These genes have also taken place meaningful difference expression during dedifferentiation of wheat embryos. These differently expressed genes might play an important role during dedifferentiation of wheat embryos.The selection and classification of MADS family genes and their corresponding target genes were made by the bioinformatics techniques.There were 8 classes transcription factors and 9 classes target genes found in dedifferentiation of wheat embryos in the Affymetrix wheat Gene Chip, among of which, 18 transcription factors and 25 target genes in mature embryos, 21 transcription factors and 16 target genes in immature embryos, respectively. The down-regulatory times of CO and PI types of transcription factor and their target genes in mature embryos were greater than in immature embryos. AP1, SQUA and AGL9 3 transcription factor and their target genes were more active in immature embryos than in mature embryos. Majority of AG and SVP transcription factor and their target genes were up-regulated in mature embryos, but they were down-regulated in immature embryos. SEP3 transcriptions factor and their target genes displayed down-regulatory tendency during dedifferentiation of wheat mature and immature embryos, and their change times were not more difference significantly between mature and immature embryos. The results showed that SEP3 transcription factor and their target genes had the similar function in mature and immature embryos dedifferentiation. In contrast, the functions of the other 7 types of transcription factors and their target genes were more difference and complex. So, it was clear that MADS family transcription factors and their target genes displayed down-regulatory tendency during dedifferentiation of wheat mature and immature embryos. These results implied that down-regulatory expression might favorite the trigger and process of dedifferentiation of wheat embryos.According to the finding of this paper, MADS-box genes also expressed during dedifferentiation of wheat embryos. This indicated that the MADS-box genes played important role not only in tissue and cell differentiation, but also in cell dedifferentiation. The expressions of different genes in dedifferentiation of wheat mature and immature embryos might affect calli regeneration capacity from the explant of them. The study in this area would not only help to reveal the molecular mechanism of wheat embryos,but also to achieve the man-made control in wheat embryo dedifferentiation.
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