Identification of putative H2O2 regulated genes during the establishment of the Sinorhizobi...

The involvement of ROS in the legume – Rhizobium symbiotic interaction has been highlighted (Santos et al., 2001; Rubio et al., 2004). This interaction is characterized by the formation of a new organ on the root, the nodule and by the penetration, in parallel, of the bacteria into the root tissue via an infection thread (IT) (Parniske and Downie, 2003; Gage, 2004). H2O2 production has been shown in ITs during the Medicago – Sinorhizobium meliloti interaction (Santos et al., 2001). Moreover, S. meliloti mutants impaired in H2O2 detoxification mechanism possess in planta symbiotic phenotypes. As H2O2 production is known to orchestrate plant gene expression, our goal is focused on identifying the H2O2 regulated genes in the symbiotic process. We focus our analysis in the M. truncatula transcriptome as we are characterising the S. meliloti H2O2 transcriptome. -M. truncatula seedlings were grown in axenic condition on modified Fahraeus medium during seven days. Then they were transferred on new plates supplemented either with dimethyl sulfoxide (DMSO, mock treatement) or diphenylene iodonium (DPI, 10 µM). Twenty four hours later, they were inoculated either with water (mock inoculation; DMSO-H2O and DPI-H2O) or wild type S. meliloti 2011 strain (DMSO-INOC and DPI-INOC). Roots without apexes were harvested 48 hours after inoculation. After RNA extraction (Trizol), quality of the treatment was verified by RT-PCR (ENOD11: inoculation efficiency; GSHS1: DNA contamination; MTC27: constitutive) Keywords: treated vs untreated comparison 8 arrays - Medicago