Iron biofortification in common bean

Iron deficiency anaemia is the most prevalent micronutrient deficiency affecting more than 2 billion people throughout of the world. Iron bioavailability may be strongly reduced by the presence in the seeds of iron absorption inhibitors, such as phytic acid (IP6) and polyphenols (PP). In different crop species low PP genotypes can be easily identified, conversely natural variability in IP6 content is not very high and the best way to gain significant IP6 reduction is by obtaining low phytic acid (lpa) mutants. Although such type of mutants have been identified in several grain crops, often IP6 reduction is associated with negative agronomic traits, such as lower seed viability and emergence, reduced plant growth rate and grain yield. These findings may limit the use of lpa mutants for iron biofortification, since acceptable agronomic performance should be guaranteed to small farmers and poor populations that would benefit from biofortified crops. Due to its worldwide consumption and nutritional qualities, common bean has been identified as a strategic target crop for iron biofortification. We have isolated a bean lpa mutant having a 90% seed IP6 reduction and showed it is defective in a MRP type ATP-binding cassette transporter (Pvmrp1) specific for IP6. Agronomic analyses of the original lpa mutant and of derived lpa lines have shown that seedling emergence, seed yield and plant growth were not affected. In vitro and in vivo analyses confirmed significant increases of iron bioavailability in bean lpa seeds.