Phytic acid: novel putative common bean mutants and tools to study its role in cell signalling

Phytic acid (InsP6) is the main storage form for phosphate in seeds InsP6. It is also a strong chelator of mono and divalent cations, such as iron, zinc, magnesium and calcium, essential minerals in the diet, thus reducing their bioavailability. For this reason InsP6 is considered an antinutrient. The reduction of InsP6 concentration in cereal and legume seeds is considered an important goal for breeding in order to increase the bioavailability of micronutrients and improve seed nutritional quality, mainly to the benefit of populations in the developing world who subsist on diets based on these crops. On the other side, InsP6 plays a key role in different plant cell processes, such as the regulation of hormone activity, abiotic and biotic stress response, calcium and sugar signalling, phosphorus homeostasis, photomorphogenesis, chromatin modification and remodeling and mRNA nuclear export. We isolated some putative common bean low phytic acid (lpa) mutants through a colorimetric assay on seeds of an ethyl methane sulfonate (EMS) mutagenized population. For some mutants the lpa phenotype was confirmed on the progeny. A candidate gene approach is in progress in order to identify the affected genes causing the lpa mutations. Alternatively, in the cases in which this strategy will not be successful a positional cloning mapping approach will be started. Moreover, we developed Arabidopsis lpa lines harbouring biosensors to monitor calcium response to different stimuli or markers for auxin and jasmonic acid distribution, and the analyses of these lines is still in progress. We will present preliminary data on the characterization of the common bean lpa mutants and on the Arabidopsis lines harbouring the different biosensors/markers.