Genetic Variability Analysis of Grains Fe, Zn and Beta-carotene Concentration of Prevalent Wheat Varieties in Iran

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1 International Journal of Agriculture and Crop Sciences. Available online at IJACS/2013/6-2/57-62 ISSN X 2013 IJACS Journal Genetic Variability Analysis of Grains Fe, Zn and Beta-carotene Concentration of Prevalent Wheat Varieties in Iran Hedieh Badakhshan 1 *, Namdar Moradi 1, Hadi Mohammadzadeh 1, Mohammad Reza Zakeri 2 1. Department of Agronomy and Plant breeding, Faculty of Agriculture, University of Kurdistan, Sanandaj, Iran 2. Department of Plant Breeding, Faculty of Advanced Studies, Islamic Azad University of Kermanshah, Iran * Corresponding author h.badakhshan@uok.ac.ir ABSTRACT: To improvement of grains quality of wheat and reduction of micronutrient malnutrition in human populations as a basic method, current wheat varieties in Iran were analyzed for diversity of micronutrients (Fe, Zn and Beta-carotene) concentrations in grain. Eighty two varieties including modern, landrace and durum wheat were grown in field condition across two years to determine the importance of genetic, environment and their interaction effects. Remarkable variation among 82 genotypes exhibited for all micronutrients concentration in grains. Based on the mean of two years, the concentration of grain Fe, Zn, protein and beta-carotene ranging from to mg Kg -1, from to mg Kg -1, from 7.5 to 15.6 percent and from 0.96 to 1.69 µg g -1 respectively. Significant differences for Fe, Zn and beta-carotene concentration of grains were existed among genotypes and years. The interaction of year by genotype was significant for Fe and Zn but not for beta-carotene. Landraces of wheat found to contain higher Zn concentration than modern and durum varieties. Highly positive correlations were revealed among Fe and Zn but not for beta-carotene. Both Fe and Zn were correlated positively with grains protein content (p< 0.001). No significant correlation was found for spike numbers and the numbers of kernels per spike and micronutrients. The results of this study showed a considerable variation for micronutrient concentration in grains between genotypes for breeding purposes such as promoting high quality cultivars with high grains micronutrient concentration or bifortification. Keywords: Beta-carotene, Biofortification, Fe, micronutrient, protein, wheat, Zn INTRODUCTION Deficiencies of micronutrients (hidden hunger) are a major global health problem and more than 2 billion people in the world are estimated to be deficient in key vitamins and minerals, particularly vitamin A, iodine, iron and zinc (FAO, 2011). Mineral elements play numerous beneficial roles due to their direct and indirect effects in both plant and human metabolism and the deficiencies or insufficient intakes of these nutrients leads to several dysfunctions and diseases in humans (Welch and Graham, 1999) and also lead to entire failure of crops and lower content of trace elements in plant parts (Cakmak, 2008). Several strategies have been suggested as intervention programmers for the reduction of micronutrient malnutrition in human populations (Ng uni et al., 2012). They include food fortification, dietary supplementation by use of complementary tablets. Other strategies are dietary diversification and micronutrient biofortification programs through plant breeding (Ng uni et al., 2012). Comparatively, plant breeding has been identified as been potentially more sustainable and less expensive, since seeds could reach a larger number of people without necessarily changing consumer s behavior (Ortiz-Monasterio et al., 2007; Cakmak, 2008; Ng uni et al., 2012). This solution, however, requires a comprehensive exploration of potential genetic resources and indepth understanding of the physiological and genetic basis of nutrient- accumulation process in crops tissues (Chatzav et al., 2010). One major strategy to improve the level of mineral nutrients and vitamins in staple food crops is to exploit the natural genetic variation in food crops (Ortiz-Monasterio et al., 2007; Cakmak, 2008; Gomez-Becerra et al., 2010a). Wheat is the major staple food crop in many parts of the world, contributing 28% of the world edible dry matter production and up to 60% of daily energy intake in several developing countries (Cakmak, 2008; Wang et al., 2011). Iran has one of the world s highest rates of wheat flour consumption, more than 300kg per capita

2 in a year (Hemphill, 2012). Therefore, the composition and nutritional quality of the wheat grain have a significant impact on human health and well-being, especially in developing countries (Chatzav et al., 2010; Wang et al., 2011). However, most of the cultivated wheat cultivars have low grain Fe and Zn contents (Cakmak et al., 2004; Cakmak, 2008; Wang et al., 2011). Cereal grains are inherently poor in concentration of micronutrients, and rich in compounds depressing the bioavailability of micronutrients such as phytic acid (Morgounov et al., 2007). The nutritional value of cereals needs to be improved through the general use of less refined flour and the selection of wheat varieties with high mineral diversity (Oury et al., 2006). A survey of rice indicated a fourfold variation in grain Zn and Fe concentrations similar variation was found in diverse wheat accessions, although Fe and Zn concentrations were generally lower and showed less genetic variability among cultivated tetraploid and hexaploid varieties than among wild diploid wheat and relatives (White and Broadley, 2005). Variation in mineral levels of wheat flour and bran has been attributed to genetic and environmental effects, their interaction, and variation in protein levels (Peterson et al., 1986; Gomez-Becerra et al., 2010a, b). Since wheat, along with rice, supplies the greatest amount of calories and protein per capita in the world, therefore represents a useful vehicle for increasing the intake of essential nutrients such as carotenoids (Genc et al., 2005). The concentration of carotenoids in wheat is small compared with that found in the fruit and vegetables. However, the daily consumption of wheat based products in populations that rely almost entirely on this grain for caloric intake, indicate that a small increase in concentration would have a large impact (Genc et al., 2005). On the other hand, certain organic compounds such as beta-carotene (pro-vitamin A) stimulate the absorption of essential elements by humans (White and Broadley, 2005). Carotenoids from a plant origin have an advantage over retinol from animal sources, because excessive may cause a toxic excess in vitamin A, whereas carotenoids can be converted to meet metabolic requirements (Sramkova et al., 2009). The objective of this study was to evaluate the genetic diversity of grains Fe, Zn and beta- carotene concentration in prevalent cultivated wheat varieties of Iran and identify varieties with higher micronutrient concentration in the grain. MATERIALS AND METHODS Plant material and experimental condition Eighty two wheat varieties including 74 of prevalent wheat varieties in Iran, five of landraces from Iran and north of Iraq and three of durum wheat varieties were used in this study. The varieties were evaluated for the grain mineral nutrient concentration of iron (Fe), zinc (Zn) and beta-carotene for two years ( ), in the research farm of University of Kurdistan (35 16 E, 47 1 N; 1375 above sea level) in Iran. Grains protein content data were available only for second year ( ). Soil samples were randomly collected from the top 0-30 cm soil depth of experimental site and analyzed for micronutrients, organic maters and ph before sowing (Table 1). The experimental design was complete block design with three replications. Each plot consisted of three rows 1 m long with 0.2 m between rows. Determination of grains Fe, Zn, beta-carotene and protein concentration Grain samples ( were digested in a mixture of Chloridric (HCL) and Perchloridric acid (HCLO4) according to Singh et al. (1999). Digested samples were analyzed for iron and zinc using flame atomic absorption spectroscopy (SpectrAA220-Varian Ltd, Mulgrave, Australia). Mineral concentrations were expressed as mg/kg dry weight, three replications were performed. Appropriate quality controls were performed for each set of measurements. Beta-carotene concentration of grains was measured according to Santra et al. (2003). Briefly; Samples (8 gr) was extracted by 40 ml of water-saturated n-butanol (WSB) and the absorbance of supernatant was measured at 440 nm by a UV- spectrophotometer. A calibration curve was made from known quantities of pure beta-carotene. Flour protein content was determined using near-infrared reflectance (NIR) spectroscopy of flour samples from each plot according to Singh et al. (1999). Statistical analysis Grains micronutrient concentration data from each year were analyzed using SAS Version 9.1 (SAS 2002). Genetic diversity among genotypes was tested by analysis of variance using proc GLM. Combined analysis of variance was done for evaluate the significance of year and genotype interactions. Associations between traits were established by the Pearson correlation coefficient. 58

3 RESULTS AND DISCUSSION Iron and zinc are two micronutrients that along with pro-vitamin A (beta-carotene) are recognized by the World Health Organization (WHO) as the most limiting due to their low bioavailability in diets based on cereals and legumes (WHO, 2002). Breeding for enhanced concentrations of Fe and Zn can be divided into a number of steps: identification of genetic variability within the range that can influence human nutrition, intogressing this variation into high yielding genotypes possessing acceptable end-use quality attributes, testing the stability of Fe and Zn accumulation across the target environment and large scale deployment of seed of improved cultivars to farmers (Ortiz-Monasterio et al., 2007). Genetic diversity for grain nutrients The concentrations of three micronutrients (Fe, Zn and beta-carotene) were determined in wheat genotypes on dry weight bases across two years and the data are presented on the table 2. The protein content of grains was measured only in second year ( ) because of some technical constraints. Among the 81 cultivars of bread wheat, the concentration of grain Fe varied by 1.64 fold, ranging from to mg Kg -1, grain Zn by 2.03 fold, from to mg Kg -1, grain protein by 2.23 fold, from 7.5 to 15.6 percent and grain beta-carotene 1.76 fold, from 0.96 to 1.69 µg g -1 (based on the mean of two years, table 2). The range of Fe and Zn concentration of bread wheat in the present study was similar to those reported in earlier researches (Oury et al., 2006; Morgounov et al., 2007; Zhao et al., 2009). ANOVA showed highly significant differences between wheat cultivars for grains Fe, Zn, protein and beta-carotene concentrations in both years (table 3). Studies with rice and wheat, and preliminary studies with wild relatives and landraces of wheat have demonstrated that considerable variation exists in grain Zn and Fe concentration (Genc et al., 2005; Gomez-Becerra et al., 2010a, b). It has been suggested that in order to have a measureable biological impact on human health, grain concentrations of Zn and Fe should be increased by at least 10 and 25 mg Kg -1 (Ortiz-Monasterio et al., 2007; Cakmak, 2008; Chatzav et al., 2010). The targets for Fe and Zn biofortification in wheat grain are around 60 and 40 mg Kg -1 respectively (Ortiz-Monasterio et al., 2007). Therefore, 11 of 81 examined varieties and most of the tested varieties contain high levels of Fe and Zn respectively in this study. According to our knowledge, the variation of carotenoides especially beta-carotene rarely reported in bread wheat. Analysis of 15 cultivars of durum and landraces in the present study, showed similar means of grain Fe to those of modern bread wheat but among the landraces and modern cultivars were significant differences for Zn and protein concentration confirmed by Orthogonal contrasts tests (p< 0.01; table 2). These results were consistent with the results reported by Zhao et al. (2009) and Murphy et al. (2008) in bread wheat. No significant differences between three classes of wheat for beta-carotene (table 2). Blanco et al. (2011) reported that wheat carotenoids concentrations are higher in cultivated varieties than in their wild counterparts. Highly remarkable variation existing among wheat varieties for grain micronutrient concentrations and protein indicated the potential for genetic improvement. Interactions among genotype and environment Analysis of the effects of year and interaction of year and genotype on Fe, Zn and beta-carotene according to combined analysis exhibited that all of the effects were significant with the exception of year by genotype interaction for beta-carotene, demonstrating the importance of environmental effects on Fe, Zn and Beta-carotene concentration of grains. Three of eight genotypes and three of five genotypes that ranked highest for Fe and Zn respectively, were the same in both years (table 4). Of the genotypes used in this study, in each two years, Gaspard (67.67 mgkg -1 ) and two landraces Shahpasand and Azar2 (61.53 and mgkg - 1 respectively) were superior in Fe, Superior genotypes in Zn were Sabalan (73.80 mgkg -1 ), Gaspard and Shahpasand (70.98 and mgkg -1 respectively), MV17, Sistan, Golestan and R1-ERW87 (1.69, 1.61, 1.51 and 1.48 µg g -1 respectively) had higher beta-carotene concentration and Bezostaya (15.6 mgkg -1 ), Omid (14.67 mgkg -1 ) and two landraces Shoaleh and Rashagol (14.77 and mgkg -1 ) had significantly higher protein than other genotypes according to second year data (based on Fisher s LSD means comparison test; p< 0.01). Non-significant interactions among genotype and year for beta-carotene indicated that major changes in these compounds may not occur in grains of wheat varieties in different years and location. Blanco et al. (2011) underlined polygenic nature as well as genotypic component of yellow pigment concentration in durum wheat although, environmental factors can influence carotenoids the genetic component is predominant in durum wheat. In previous studies, significant genotype environment interactions for grain nutrient concentrations such as Fe and Zn were reported for bread wheat varieties (Oury et al., 2006; Morgounov et al., 2007; Murphy et al., 2008; Wang et al., 2011) as well as for their wild and cultivated relatives (Peleg et al., 2008; Chatzav et al., 2010; Gomez-Becerra et al., 2010a, b). Because the genotype variance was greater than variety year interaction for grains Fe and Zn concentration (table 4) thus, it can be concluded that there are 59

4 non-cross-over interactions and therefore reasonable advances in selection and breeding can be expected as suggested by previous studies (Peterson et al., 1986; Peleg et al., 2008; Chatzav et al., 2010). The complexity of the inheritance of grain Fe and Zn concentrations in wheat, plus the associated low heritability and the large environment and genotype environment interaction effects, slow progress in the genetic analysis of these traits. However, in spite of these challenges there is evidence that breeding for increased levels of micronutrients is feasible (Ortiz-Monasterio et al., 2007). Analysis of correlation among micronutrients Positive highly significant correlations (p 0.001) among grains Fe, Zn and protein concentrations were observed but grains beta-carotene did not significantly correlated to grains Fe, Zn and protein (table 5). Significant correlation between Fe, Zn and protein were observed in most of the studies (Cakmak et al., 2004; Morgounov et al., 2007; Demirkiran, 2009; Peleg et al., 2009; Zhao et al., 2009; Chatzav et al., 2010; Wang et al., 2011). This has implicated for the possibility of combine selection for these micronutrients in a single agronomic background. Genetic mapping in various wheat populations confirmed QTL co-localization conferring high Protein, high Zn and high Fe (Peleg et al., 2009). Likewise, co-localization of QTLs for Zn and Fe concentrations has been reported in rice (Garcia- Oliveira et al., 2009).Some genes like grain protein content-b1 gene (Tt-NAM-B1; Gpc-B1) which is located on chromosome 6BS, can increase the Fe and Zn translocation from leaves to seeds resulting in increased Fe and Zn accumulation in seeds (Oury et al., 2006; Cakmak, 2008; Zhao et al., 2009; Wang et al., 2011). The orthologous gene (Tt- NAM-A1) is located on chromosome 6AS and the paralogous gene (Tt- NAM-B2) is located on chromosome 2BS (Wang et al., 2011). Similar relationship between protein, Fe and Zn has been reported in sorghum (Ng uni et al., 2012), rice (Garcia- Oliveira et al., 2009) and bean (Gelin et al., 2007). No significant correlation were among grains protein, micronutrient concentration (Fe, Zn, betacarotene) and measured yield component traits such as spike length and kernels per spike number along with plant height and peduncle length (results has not shown). Some earlier studies reported that plant productivity exhibited positive and significant correlations with grain Zn and Fe (Murphy et al., 2008; Chatzav et al., 2010; Gomez-Becerra et al., 2010b), but in some previous reported researches, increasing grain yield was found not to result in lower micronutrient concentrations in wheat grain (Cakmak et al., 2004; Murphy et al., 2008; Wang et al., 2011). The six genomic regions (2B, 2B, 4A, 4B, 5A, 7B) conferring grain yield as studied by Peleg et al. (2009) were not significantly associated with QTLs for Zn, Fe or other minerals. Thus, the improve grain protein and mineral concentration is not necessarily expected to reduce productivity. However, negative significant correlations occurred between Fe, Zn, yield component and morphological traits reported by some authors (Oury et al., 2006; Morgounov et al., 2007; Zhao et al., 2009; Wang et al., 2011). So, they concluded that modern varieties with high grain yield and grain yield component traits tend to have lower concentrations of micronutrients in the grain. Estimation of broad sense heritability Estimates of broad sense heritability (h 2 B) ranged from 23.08% for beta- carotene to 90.62% for Fe in first year and from 38.46% for beta-carotene to 90.90% for Zn in second year. Broad sense heritability estimation of micronutrients exhibited medium to high for each year separately (table 3). Whereas, based on combined analysis, broad sense heritability estimates ranged from 14.96% for Fe to 55% for Zn (table 4). Lower level of estimated broad sense heritability in current study indicated the strong environmental effect and proportion of phenotypic variance attributable to environmental variance to genotype variance especially for Fe and beta-carotene (table 4). Heritability estimates are limited to experimental material and setup, and may differ widely in the same crop and same trait (Garcia- Oliveira et al., 2009). Heritability is a measure of genetic differences among individuals in a population, not simply of whether or not a trait is inherited (Gomez-Becerra et al., 2010b). Controversy to the results of the present study, moderate to high heritability estimates (h 2 B) for total as well as for individual carotenoides such as beta-carotene indicated by Blanco et al. (2011) in durum wheat. High genetic diversity was fond among cultivated wheat genotypes in two successive years for micronutrient concentration in grains indicating the remarkable potential for improvement of their grains quality and introduction of varieties with the higher grains micronutrient concentration. Highly positive significant correlation between Fe, Zn and protein revealed that concurrently improvement of these nutrients are possible. Non- significant correlation among yield component traits of wheat and grains micronutrient concentration exhibited that varieties with high micronutrient concentrations not necessarily tend to produce lower yield. So, this non-relationship is useful for the biofortification of high yielding wheat varieties. 60

5 Table 1. Major soil properties of the experimental location Fe Mn Cd Zn Ni Ca ph Ec K N(total) mg kg -1 mg kg -1 µs/cm mg kg -1 Soil texture Clay- loam Table 2. Micronutrient concentration in 82 wheat genotypes grains evaluated in two years First year Second year Means of two years Fe Zn B-car Fe Zn B-car Protein Fe mgk - Zn mgk -1 B-car mgk -1 mgk -1 µgg -1 mgk -1 mgk -1 µgg -1 1 % µgg -1 Total min n=82 Max Mean± 59.33± ± ± ± ± ± ± ±0. 14 Modern min Bread Max wheat varietie s n=67 Mean± 59.26± ± ± ± 6.94 b 44.58±9. 44 c 1.14± ±1. 62 b 50.25± ±6. 73 b 1.25±0. 15 Landrac min es Max n=12 Mean± 60.31± ± ± ±7.5 a 52.39± b 1.12± ±1. 5 a 52.40± ±7. 96 a 1.27±0. 13 Durum min wheat Max n=3 Mean± 57.15± ± ± ±4.4 7 ab 59.51±6. 93 a 1.26± ±2. 28 b 50.48± ±3. 97 a 1.21±0. 11 Fe1, iron; Zn, zinc; B-car, beta-carotene a and b are significant differences at 5% Table 3. Analysis of variance for grains micronutrients and protein concentration in each year separately First year Second year Mean of Squares Mean of Squares Source df Fe Zn B-car Fe Zn B-car Protein Varieties *** 98.02*** 0.04* 94.06*** *** 0.038** 5.16*** Blocks * * ns *** ns 0.548*** 39.56*** Error CV h 2 B 90.62% 75.76% 23.08% 74.55% 90.90% 38.46% 75% Level of significance: *** p< 0.001, ** p<0.01, * p<0.05 and ns non-significant CV: coefficient of Variation h 2 B: Broad sense heritability Table 4. Combined analysis of variance for micronutrients Fe, Zn and Beta carotene concentration of grains Mean of Squares df Fe Zn Beta-carotene Year *** *** 2.00*** Block(Year) Varieties *** *** 0.05*** Year Varieties *** *** ns Error CV h 2 B 14.96% 55% 35.93% Level of significance: *** p< 0.001, ** p<0.01, * p<0.05 and ns non-significant CV: coefficient of Variation h 2 B: Broad sense heritability Table 5. Correlation analysis among grains micronutrient concentration Fe Zn Protein Zn *** Protein *** *** Beta-carotene Level of significance: *** p<

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