Systematic functional characterization of transcription factors whose expression is induced in the nodulation process of a model leguminous plant, Lotus japonicus

Abstract

Symbiotic nitrogen fixation of leguminous plant is established through complex signal exchange between rhizobacterium. Genome analysis of a model legume Lotus japonicus is in progress. Using the genome sequence information, several key regulatory genes of Nod factor perception and initial signal transduction were identified. We took a comprehensive approach to analyze the gene expression profile of the nodulation process by SAGE method (Asamizu et al. 2005). A cDNA array study on this process was reported (Kouchi et al. 2004). These transcriptome analyses led us to identify 20 transcription factors whose expression is up regulated in the nodulation process. In this study, we took several approaches to functionally characterize them. Nodules over-expressing the TFs were constructed utilizing hairy root transformation system and downstream genes were examined by oligo array experiments. A TILLING mutant showing considerable delay in nodule formation compared to wild type was obtained. The latest status will be presented.