Abstract
Leguminous plants have the capacity to perform a nitrogen-fixing endosymbiosis with rhizobia. The plant symbiotic program is triggered by perception of highly specific signals, Nod factors, secreted by rhizobia. Invasion of rhizobia followed by differentiation of a nitrogen-fixing nodule involve complex interaction mechanism of both organisms. In the model legume Lotus japonicus, cDNA macroarray analysis of the nodule formation process has been reported (Kouchi et al. 2004). For a comprehensive approach to analyze the expression profile of the nodulation process, we performed Serial Analysis of Gene Expression (SAGE) of uninfected root and nodulating root abundant in nodule primordia. We have a special interest in transcription factors because they may represent key regulators of the nodulation program. The cDNA array and SAGE analyses have led us to identify 22 transcripts harboring sequence similarity to known transcription factors. Utilizing the hairy root transformation system, we initiated functional analysis of these genes.
