Involvement of an R2R3-MYB transcription factor gene AtMYB118 in embryogenesis in Arabidopsis

MYB transcription factors play important roles in various developmental processes in plants. Here we report the characterization of AtMYB118, a gene encoding a putative R2R3-type MYB transcription factor, which expresses predominantly in siliques. Real-time quantitative PCR analysis and in situ hybridization showed that the transcripts of AtMYB118 were mainly detected in developing embryos. Constitutive over-expression of AtMYB118 resulted in pleiotropic phenotypes, including dwarfism, compact rosettes, backward curly-leaves, smaller flowers and siliques, and premature seed dehydration at the tip of siliques. Microarray analysis showed that many genes encoding proteins accumulated during embryogenesis were remarkably up-regulated in AtMYB118-over-expressed transgenic plants, including late embryogenesis abundant proteins (LEA proteins), storage proteins, seed maturation proteins, and proteins related with seed dehydration, desiccation and ABA signaling pathway. These results suggest that AtMYB118 may play an important role during embryogenesis and seed maturation.