Genetic Selection for Enhanced Bioavailable Levels of Iron in Bean (Phaseolus vulgaris L.) Seeds

Abstract

The bioavailability of Fe from 24 select genotypes of bean (Phaseolus vulgaris L.) seeds containing a range of concentrations of Fe, myo-inositol pentaphosphate plus phytic acid (IP5+IP6), and tannins was studied using a rat model. Bean accessions, selected from field trials for their variations in Fe, phytate, and tannin seed concentrations, were grown in a greenhouse in nutrient solutions radiolabeled with (59)Fe. Mature seeds were autoclaved and lyophilized. Test meals (containing 1 g of dried bean, 0.5 g of sucrose, and 1 g of basal Fe-deficient diet) were fed to marginally Fe-depleted weanling rats over a 3-h period; rats were radioassayed in a gamma-spectrometer immediately after feeding and daily thereafter for the next 10 d. Radioiron retention data were used to calculate percent Fe absorption (i.e., Fe bioavailability) from the meals. Seed Fe concentrations ranged from 52 to 157 microg g(-)(1) dry weight. There was a tendency to also select for higher Zn concentrations in the beans when selecting for high Fe concentrations. The Fe bioavailability to rats from test meals depended on the genotype and varied from 53% to 76% of the total Fe. Bean genotypes with higher seed Fe concentrations resulted in increased amounts of bioavailable Fe to rats. There was no significant correlation between the Fe concentration in different bean genotypes and Fe bioavailability to rats attributable to variations in IP5+IP6 or tannins, even though these antinutrients varied widely (i.e., from 19.6 to 29.2 micromol of IP5+IP6 g(-)(1) and from 0.35 to 2.65 mg of tannins g(-)(1)) in the test meals. Other unknown seed factors (i.e., antinutrients or promoter substances) may be contributing factors affecting Fe bioavailability from bean seeds.

The Bean – Naturally Bridging Agriculture and Human Wellbeing

“…The grain legumes, on the contrary, have a high starting point from where to seek improvements. Beans are superior to cereals in their macro-and micronutrient content as demonstrated in Table 1, in agreement with [9] although trials with other pulses under farmers' conditions have demonstrated that genetic potential are not always expressed under more marginal conditions. Furthermore, the legumes holds a potential for entering the diet in a diversity of ways, ranging from the dry mature seeds, to green seeds and pods as well as leaves used as vegetables, see also [10].…”

Efeito do processamento doméstico sobre o teor de nutrientes e de fatores antinutricionais de diferentes cultivares de feijão comum

“…Deshpande et al (1982) verificaram que o conteúdo de taninos em feijões depende em grande parte da presença ou não do tegumento e de sua coloração, como também varia dependendo da espécie do feijão (CHIARADIA; GOMES, 1997). O conteúdo de taninos dos feijões pigmentados inteiros é maior que nos feijões descascados (DESHPANDE et al, 1982) e os feijões brancos possuem quantidades muito baixas (WELCH et al, 2000) enquanto que os vermelhos e os pretos têm níveis significativamente maiores, portanto, a maior concentração de polifenóis é encontrada em cascas de sementes coloridas, porém os feijões vermelhos apresentam maior concentração que os pretos (BRESSANI et al, 1981;BRESSANI et al, 1991).…”

“…Os teores de IP6 + IP5 são similares aos reportados por Welch et al (2000) e House et al (2002) para feijões cozidos sem maceração, porém são superiores aos citados por Villavicencio et al (2000) para feijões cariocas crus e cozidos com água de maceração, e aos reportados por Lombardi-Boccia et al (1998) para feijões brancos crus e cozidos com água de maceração.…”

Genetic control of potassium content of common bean seeds

“…Legumes are a superior source of minerals compared to cereals (Welch et al, 2000). In Latin America, bean consumption provides 8 to 27% of the necessary K to satisfy the daily nutritional requirement (Pennington & Young, 1990).…”