IRON FORTIFICATION AND BIOFORTIFICATION IN CHICKPEA (Cicer arietinum L.)

Abstract

Iron (Fe) deficiency is one of the most common nutritional disorders in both developing and developed countries due mainly to insufficient intake of bioavailable Fe. Chickpea (Cicer arietinum L.) is the world’s second most important pulse crop and staple food in many developing countries where Fe deficiency is severe. This research examined Fe fortification and biofortification to increase Fe concentration in chickpea seeds that ultimately may enhance Fe bioavailability in the human diets. Study I was designed to increase Fe concentration and Fe bioavailability in chickpea seeds and flour through fortification. Three fortificants [FeSO4·7H2O (ferrous sulfate hepta-hydrate), FeSO4·H2O (ferrous sulfate mono-hydrate) and NaFeEDTA (ethylenediaminetetraacetic acid Fe (iii) sodium salt)] were applied by a spraying and drying method. This study revealed that using a fortificant with Fe concentration of 2000 µg g-1, the fortified split desi seeds (dal), desi flour and kabuli flour could provide 18-19 mg, 16-20 mg and 11-19 mg Fe per 100 g product, respectively. The overall consumer acceptability using a nine-point hedonic scale for sensory evaluation demonstrated that NaFeEDTA-fortified cooked dehulled desi chickpea (soup and chapatti) had the highest score among the three fortificants compared to the non-fortified control. Lightness (L*), redness (a*) and yellowness (b*) of the Fe-fortified products changed slightly over time. However, no other organoleptic changes occurred. The Fe bioavailability of the cooked fortified chickpea split desi seed (soup), desi chapatti and kabuli chapatti increased by 5.8-10.5, 15.3-25.0 and 4.8-9.0 ng ferritin mg-1 protein, respectively. Both desi and kabuli chapattis fortified with FeSO4·7H2O had higher Fe bioavailability and consumer preference compared to those fortified with FeSO4·H2O and NaFeEDTA. The increase in Fe concentration and bioavailability in the fortified chickpea products demonstrated that these products could provide a significant portion of the recommended daily Fe requirement. Study II was aimed at increasing Fe concentration in chickpea seeds through an agronomic approach. An experiment was conducted to evaluate the effects of different doses of soil applied Fe fertilizer (0 kg ha-1, 10 kg ha-1 and 30 kg ha-1 of Fe-EDDHA) on seed Fe content of 18 chickpea cultivars under field conditions. This study revealed that the application of synthetic Fe chelates on chickpeas across two years and two locations in Saskatchewan had significant effects (p < 0.01) on plant biomass and seed Fe concentration. The highest seed Fe concentration was obtained from X05TH20-2 and CDC Frontier cultivars (58 and 56 mg Fe kg-1 seed, respectively). Seeds of these two cultivars can provide approximately 6 mg Fe 100-1 g seeds. Thus, a 58 and 83 g serving of Fe biofortified chickpea seeds can provide adequate amount (50%) of Fe for children at the age groups 1-3 (7 mg Fe day-1) and 4-8 (10 mg Fe day-1) years, respectively. At the 19-50 years age group, 67 and 150 g of Fe biofortified chickpea seeds can provide adequate amount (50%) of Fe for men (8 mg Fe day-1) and women (18 mg Fe day-1). Study III examined Fe absorption and accumulation at six different growth stages (V3, V10, R2, R5, R6, and RH) in roots, stems, leaves, flowers, and seeds of six diverse chickpea genotypes (CDC 551-1, CDC Verano, FLIP 97-677C, Kalka 064, Sarik 067, and Cermi 075). The highest and lowest accumulations of Fe throughout the plant growth stages were found in the roots and stems, respectively. Relative expressions of genes associated with Fe metabolism including FRO2 and IRT1 for Fe uptake, NRAMP3, V1T1, and YSL1 for Fe transportation, FER3 for Fe storage, two novel candidate genes: GCN2, and WEE1 were studied. Results of gene expression analysis confirmed that FRO2 and IRT1 genes were involved in Fe uptake and had greater expression in roots than shoots of chickpeas under Fe sufficient conditions than Fe deficient conditions. The transporter genes: NRAMP3, V1T1, YSL1 along with the storage gene FER3 showed higher expression in shoots than in roots. Novel candidate gene WEE1 for Fe metabolism was expressed at a higher level in roots under Fe sufficient conditions; however, GCN2 showed over-expression in roots under Fe deficient conditions. The findings from the current research could help to increase Fe concentration and Fe bioavailability in chickpea seeds and processed meals, as well as help to develop chickpea varieties with high Fe concentration in seeds. Consumption of Fe-fortified chickpea could provide a major portion of the recommended dietary allowance for Fe, which could help to reduce Fe deficiency in target populations.