Phytate and mineral elements concentration in a collection of Italian durum wheat cultivars

Mineral deficiencies are prevalent in human populations and the improvement of the mineral content in cereal products represents a possible strategy to increase the human mineral intake. Nevertheless, most of the inorganic phosphorus (Pi) present in mature cereal seeds (40-80%) is stored as phytate, an anti-nutritional factor that forms complexes with minerals such as Ca, Mg, Zn and Fe reducing their bioavailability. The present study was undertaken: (i) to determine the variation in phytate and mineral concentrations in the whole grains of 84 Italian durum wheat (Triticum durum Desf.) cultivars representative of old and modern germplasm; (ii) to estimate the magnitude of genotypexenvironment interaction effects; and (iii) to examine the interrelationships among mineral concentrations in durum wheat with the final aim to identify superior durum wheat cultivars that possess low phytate content and high concentration of mineral elements in their whole-wheat flour. The cultivars were grown in field trials during 2004-2005 at Foggia, Italy and during 2005-2006 at Foggia and Fiorenzuola d'Arda--Southern and Northern Italy. The phytate content was estimated indirectly by using a microtitre plate assay evaluating the Pi absorbance at 820nm, while the Cu, Fe, Mn, Ca, K, Mg, Na and Zn mineral contents were determined by ICP/OES. The contents of Zn and Fe across years and locations ranged from 28.5 to 46.3mg/kg for Zn with an average of 37.4mg/kg and from 33.6 to 65.6mg/kg for Fe with an average of 49.6mg/kg. Pi grain content was between 0.46 and 0.76mg/g showing a positive correlation with all minerals except Cu and Zn. Although breeding activity for Fe and Zn would be difficult because GxE interaction is prevalent, multi-location evaluation of germplasm collection help to identify superior genotypes to achieve this objective. The results here reported open the possibility of designing a specific breeding program for improving the nutritional value of durum wheat through the identification of parental lines with low-Pi and high minerals concentration in whole grains.