Common bean WRKY and bHLH TFs differentially regulated in strain-specific symbiosis

ELSZTEIN C, BEKER MP, PELTZER-MESCHINI E, ZANETTI ME, BLANCO F, AGUILAROM

Mar del Plata, Buenos Aires, Argentina

Congreso; XLIII Reunión anual de SAIB; 2007

Sociedad Argentina de Investigaciones en Bioquímica y Biología Molecular

Common beans ( ) establish symbiosis with the soil rhizobia resulting in nitrogen fixation within a newly formed organ, the nodule. We have previously shown coevolution of the symbiotic partners resulting in a preference in nodulation by strains of rhizobia from the same geographical region. In order to identify genes of the plant involved in this strain selection, 11502 ESTs were generated from root hairs of Mesoamerican common beans inoculated with . One hundred and ninety genes for signal perception and transduction, transcriptional activation and hormone responses, out of 2108 independent sequences we examined, were selected and spotted in a macroarray. Membranes were hybridized with cDNAof roots inoculated with different strains to identify genes differentially induced in the more efficient interaction. Two of the differentially identified genes that were confirmed by qRT-PCR are predicted to encode transcription factors belonging to the WRKY and helix-loop-helix family, involved in pathogen perception and cell differentiation respectively. Transcript levels of these genes in response to different strains of rhizobia and regulation by plant hormones were analyzed by qRT-PCR. Understanding competitiveness and strain specificity is of vital importance to develop inoculants that can out-compite the indigenous strains present in the soil.