Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/1/2004
Publication Date: 5/1/2005
Citation: Cichy, K.A., Forster, S., Grafton, K.F., Hosfield, G.L. 2005. Inheritance of seed zinc accumulation in navy bean. Crop Science. 45(3):864-870.
Interpretive Summary: In developed countries of the world, many consumers are foregoing the eating of meat in their diets. People embracing vegetarian diets often consume large amounts of legumes to satisfy dietary protein requirements. Dry bean (Phaseolus vulgaris L.) is frequently the food legume of choice to supply protein to vegetarian consumers. Although dry bean is a source of dietary zinc, beans do not supply enough zinc to satisfy recommended daily requirements for this nutrient. Hence, human zinc deficiency is a widespread condition prevalent in people who consume legume-based diets. Because large variation for dry bean seed zinc concentration exists, a way to reduce the incidence of zinc deficiency may be through the development of high zinc dry bean cultivars. A study was conducted to determine the inheritance of seed zinc in navy bean and ascertain whether it is feasible to significantly increase seed zinc concentration in bean seeds through classical genetic technology. We found that a single dominant gene controls high zinc concentration in navy bean. Moreover, genetic selection for increased seed zinc is relatively rapid and straightforward to achieve. In addition to genetic manipulation of beans for high seed zinc, improving the zinc fertility of the soil can also increase the concentration of this element in seed. The presence of significant variability among dry bean genotypes for seed zinc concentration, and the fact that seed zinc is under simple genetic control, makes plant breeding an attractive technology to benefit human health. Increases in seed zinc concentration of new dry bean cultivars provide a sustainable way to alleviate zinc deficiency in people consuming vegetarian diets that contain large amounts of food legumes as dietary components.
Technical Abstract: Human zinc (Zn) deficiency is a widespread condition prevalent in people consuming grain and legume based diets. Dry beans (Phaseolus vulgaris, L.) are frequently the major protein source in such diets. One way to reduce the incidence of zinc deficiency may be through the development of high zinc dry beans. Large variation for dry bean seed zinc concentration exists, which would aid in the development of zinc-rich cultivars. The objectives of this study were to determine the inheritance of seed zinc levels in navy bean and to measure seed phytic acid (PA) levels in relationship to seed zinc concentration as an indicator of zinc bioavailability. A high seed Zn cultivar 'Voyager' and a low seed Zn cultivar 'Albion' were used to create the F2 and backcross populations that were field grown in 1999 and 2000. The results of this experiment suggest that a single dominant allele controls the high seed Zn concentration in the Voyager/Albion cross. In addition, phytic acid levels between the parent cultivars used in this study showed little variability and there was no strong correlation between seed Zn and PA concentrations. The development of dry bean cultivars with increased seed Zn levels should be possible through breeding.