Expression profiles in barley microspore embryogenesis

In barley, microarray technology has allowed to study the gene expression profiling associated with the stress pretreatment phase of microspore embryogenesis, where the reprogramming of microspores takes place. Transcriptome analysis of anthers before and after four days of mannitol pretreatment, revealed changes in the expression of 2,673 genes. A thorough study of these differentially expressed genes indicated that microspores maintained their cell cycle machinery in a steady state during stress pretreatment and underwent a major reorganization of metabolic pathways accompanied by a multidimensional stress response. Up-regulation of transcription factors related to stress responses and changes in developmental programmes took place during the pretreatment. Preliminary studies have indicated that YABBY5, ZML2, CURLY LEAF and ICE1 transcription factors have a stress pretreatment specific induction and, therefore, could play a direct role in microspore reprogramming.