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In wheat, nutrients are transported to seeds via the phloem yet access to this vascular tissue for exudate collection and quantitative analysis of elemental composition is difficult. The purest phloem is collected through the use of aphid stylectomy with volumes of exudate collected normally in the range of 20-500 nl. In this work a new method using inductively coupled plasma mass spectroscopy (ICP-MS) was developed to measure the concentration of K, Mg, Zn and Fe in volumes of wheat (Triticum aestivum, genotype Samnyt 16) phloem as small as 15.5 nl. This improved method was used to observe changes in phloem nutrient concentration during the grain loading period. There were statistically significant increases in phloem Mg and Zn concentration and a significant decrease in K over the period from 1-2 days after anthesis (DAA) to 9-12 DAA. During this period, there was no statistically significant change in phloem Fe concentration.

Measuring genotypic variation in Fe is an impor tant task for plant breeders trying to biofortify wheat (Triticum aestivum L.), but levels of Fe are often enhanced in wheat seed due to soil derived contamination. Seed Al levels can be used to identify genotypes that are con taminated with Fe. The sources of contamina tion were identified and removed by milling the wheat grains in a modified Kett mill for 5 s before analysis. Thirty contaminated lines from Australia and 240 contaminated lines from p akistan were cleaned for the validation of the 5 s milling method. Before cleaning, average Al concentrations were 10 mg kg1 . After cleaning, 183 out of the 240, or 76%, had Al less than 5.0 mg kg -1 , and average Al levels were 4.2 mg kg -1 . Therefore, the cleaning procedure was highly successful in reducing Al levels in contaminated samples. The ratio between Al removed and Fe removed was fairly consistent and followed a 1:1 relationship across two environments. Twenty genotypes of a wheat population were evalu ated for their Fe concentration before and after cleaning and ranking changed significantly and cleaning also improved the precision of quanti tative trait loci (QTL) analysis, with QTL QGFe. ta-3B having a logarithm of the odds score of 1.1 before cleaning, which rose to 3.4 after clean ing. The method provides a valuable cleaning procedure for plant breeders wanting to ana lyze wheat seed and also provides evidence for reducing the influence of soil Fe contamination on seed by simply adjusting the Fe concentra tions based on the level of Al in the grain.

Iron and zinc deficiencies are human health problems found throughout the world and biofortification is a plant breeding-based strategy to improve the staple crops that could address these dietary constraints. Common bean is an important legume crop with two major genepools that has been the focus of genetic improvement for seed micronutrient levels. The objective of this study was to evaluate the inheritance of seed iron and zinc concentrations and contents in an intra-genepool Mesoamerican × Mesoamerican recombinant inbred line population grown over three sites in Colombia and to identify quantitative trait loci (QTL) for each mineral. The population had 110 lines and was derived from a high-seed iron and zinc climbing bean genotype (G14519) crossed with a low-mineral Carioca-type, prostrate bush bean genotype (G4825). The genetic map for QTL analysis was created from SSR and RAPD markers covering all 11 chromosomes of the common bean genome. A set of across-site, overlapping iron and zinc QTL was discovered on linkage group b06 suggesting a possibly pleiotropic locus and common physiology for mineral uptake or loading. Other QTL for mineral concentration or content were found on linkage groups b02, b03, b04, b07, b08 and b11 and together with the b06 cluster were mostly novel compared to loci found in previous studies of the Andean genepool or inter-genepool crosses. The discovery of an important new locus for seed iron and zinc concentrations may facilitate crop improvement and biofortification using the high-mineral genotype especially within the Mesoamerican genepool.

Zinc (Zn) is an essential nutrient for plants with a major role in healthy root growth. Zinc is essential for maintaining root membrane integrity, but the effective Zn concentration required may depend on the crop genotype. Zinc-efficient and inefficient wheat cultivars (Triticuum aestivum cv. Excalibur and Gatcher, respectively) were grown in deep soil cores in calcareous subsoil with low micronutrient levels, and high pH and boron. Plants were grown in soil with or without basal nutrients (excluding Zn) and with or without addition of Zn. Components of yield and nutrient use efficiency were measured. Although Gatcher produced 47% more dry weight of tops and double the root length density of Excalibur at maturity, Excalibur was much more efficient in terms of Zn uptake by roots and seven-fold more efficient than Gatcher in partitioning Zn to grain production.

Low-molecular-weight borate complexes were isolated from canola (Brassica napus) and wheat (Triticum aestivum) phloem exudates, as well as the cytoplasm of the fresh-water alga Chara corallina, and identified using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Phloem exudate was collected from field-grown canola inflorescence stalks by shallow incision, while wheat phloem exudate was collected by aphid stylectomy. Chara cytoplasm was collected by careful manual separation of the cell wall, vacuole, and cytosolic compartments. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry showed the presence of isotopic borate complexes, at mass-to-charge ratio of 690.22/691.22 in the canola and wheat phloem and at 300.11/301.11 in canola phloem and Chara cytoplasm. Using reference compounds, the borate complexes with mass-to-charge ratio 690.22/691.22 was identified as a bis-sucrose (Suc) borate complex in which the 4,6-hydroxyl pairs from the two α-glucopyranoside moieties formed an [L2B]−1 complex. Further investigation using liquid chromatography electrospray ionization triple quadrupole mass spectrometry analysis confirmed the presence of the bis-Suc borate complex in wheat phloem with a concentration up to 220 μ m. The 300.11/301.11 complex was putatively identified as a bis-N-acetyl-serine borate complex but its concentration was below the detection limits of the liquid chromatography electrospray ionization triple quadrupole mass spectrometer so could not be quantified. The presence of borate complexes in the phloem provides a mechanistic explanation for the observed phloem boron mobility in canola and wheat and other species that transport Suc as their primary photoassimilate.

Micronutrient malnutrition, often called 'hidden hunger', affects over two billion people globally. This is particularly problematic in developing countries where widespread zinc (Zn) deficiency exists as a result of a predominantly plant-based diet. Furthermore, supplemental fertilizers are often unavailable or unaffordable in impoverished regions where soil infertility is common. Delivery of more Zn via food grains is theoretically possible through selective breeding strategies, but severe technical difficulties associated with trace element research have limited research on the underlying genetic components of Zn nutrition. Genetic dissection of Zn nutrition involved a pre-existing doubled haploid mapping population of barley (Hordeum vulgare). Association of mineral nutrient accumulation traits with regions of the barley genome was determined in two seasons of growth to maturity, using mapmanager qtx and QGene 4.0. Nine genetic loci segregating in the population associated clearly with measured traits, including five that contributed to grain Zn status. Pooling two-row doubled haploids by selecting the three most favourable alleles increased grain Zn content and concentration by an average of 53 and 75%, respectively. These results will inform breeding efforts for increased Zn density in the major food grain, wheat (Triticum aestivum), by enabling syntenic marker-assisted selection in conventional breeding programmes.

Selenium (Se) is essential for humans and animals but is not considered to be essential for higher plants. Although researchers have found increases in vegetative growth due to fertiliser Se, there has been no definitive evidence to date of increased reproductive capacity, in terms of seed production and seed viability. The aim of this study was to evaluate seed production and growth responses to a low dose of Se (as sodium selenite, added to solution culture) compared to very low-Se controls in fast-cycling Brassica rapa L. Although there was no change in total biomass, Se treatment was associated with a 43% increase in seed production. The Se-treated Brassica plants had higher total respiratory activity in leaves and flowers, which may have contributed to higher seed production. This study provides additional evidence for a beneficial role for Se in higher plants.

Micronutrients are essential elements needed in small amounts for adequate human nutrition and include the elements iron and zinc. Both of these minerals are essential to human well-being and an adequate supply of iron and zinc help to prevent iron deficiency anemia and zinc deficiency, two prevalent health concerns of the developing world. The objective of this study was to determine the inheritance of seed iron and zinc accumulation in a recombinant inbred line (RIL) population of common beans from a cross of low × high mineral genotypes (DOR364 × G19833) using a quantitative trait locus (QTL) mapping approach. The population was grown over two trial sites and two analytical methods (Inductively Coupled Plasma Spectrometry and Atomic Absorption Spectroscopy) were used to determine iron and zinc concentration in the seed harvested from these trials. The variability in seed mineral concentration among the lines was larger for iron (40.0–84.6 ppm) than for zinc (17.7–42.4 ppm) with significant correlations between trials, between methods and between minerals (up to r = 0.715). A total of 26 QTL were identified for the mineral × trial × method combinations of which half were for iron concentration and half for zinc concentration. Many of the QTL (11) for both iron (5) and zinc (6) clustered on the upper half of linkage group B11, explaining up to 47.9% of phenotypic variance, suggesting an important locus useful for marker assisted selection. Other QTL were identified on linkage groups B3, B6, B7, and B9 for zinc and B4, B6, B7, and B8 for iron. The relevance of these results for breeding common beans is discussed especially in light of crop improvement for micronutrient concentration as part of a biofortification program.

Fructans are prebiotics, with potentially beneficial effects on human health. This study aimed to examine genetic variation in wheat grain fructan content using a simplified analytical method. The method involves extracting fructans from wheat grain followed by enzymatic hydrolysis to break down fructans into monosaccharides that can then be quantitatively measured by anion-exchange liquid chromatography coupled with pulsed amperometric detection. The modified procedure is reliable and allows the handling of large numbers of flour samples at a low cost, and could therefore be useful for assessing large numbers of wheat breeding lines. Using this method, grain samples taken from 19 bread wheat cultivars and breeding lines grown in both glasshouse and the field were analysed for grain fructan content. In addition, grain samples of 29 international wheat landraces and 14 new wheat breeding lines from the International Maize and Wheat Improvement Center (CIMMYT) were surveyed for their fructan contents. There was significant genotypic variation among these materials, with grain fructan content ranging from 0.7 to 2.9% of grain dry weight. There was no evidence of strong genotype-by-environment interaction; the fructan contents of field-grown grain samples were positively correlated ( r = 0.83) with those of glasshouse-grown samples of the same cultivars. It should therefore be possible to investigate the genetic control of variation for this trait using the simplified HPLC method and to select effectively for increased grain fructan content in wheat breeding.

Fructans (fructo-oligosaccharides) are prebiotics that are thought to selectively promote the growth of colonic bifidobacteria, thereby improving human gut health. Fructans are present in the grain of wheat, a staple food crop. In the research reported here, we aimed to detect and map loci affecting grain fructan concentration in wheat using a doubled-haploid population derived from a cross between a high-fructan breeding line, Berkut, and a low-fructan cultivar, Krichauff. Fructan concentration was measured in grain samples grown at two locations in Australia and one in Kazakhstan. Fructan concentration varied widely within the population, ranging from 0.6 to 2.6% of grain dry weight, and was quite repeatable, with broad-sense heritability estimated as 0.71. With a linkage map of 528 molecular markers, quantitative trait loci (QTLs) were detected on chromosomes 2B, 3B, 5A, 6D and 7A. Of these, the QTLs on chromosomes 6D and 7A had the largest effects, explaining 17 and 27% of the total phenotypic variance, respectively, both with the favourable (high-fructan concentration) alleles contributed from Berkut. These chromosome regions had similar effects in another mapping population, Sokoll/Krichauff, with the favourable alleles contributed from Sokoll. It is concluded that grain fructan concentration of wheat can be improved by breeding and that molecular markers could be used to select effectively for favourable alleles in two regions of the wheat genome.

Zinc (Zn) deficiency and heat stress during grain filling occur in a number of important wheat growing regions around the world. The changes in grain protein composition due to high temperature are well documented, but little is known about the effect of grain Zn and its interaction with heat stress. Six field experiments were conducted at sites differing in grain filling temperatures to examine these effects. Two varieties of bread wheat were grown at six rates of Zn, including foliar sprays of Zn. The relative amounts of gliadin and polymeric protein were measured by size exclusion HPLC. Applying Zn increased grain yield at three sites and altered protein quality at two of these. Foliar Zn applications doubled grain Zn concentration, reduced the proportion of gliadin and SDS-unextractable polymeric protein and increased the proportion of SDS-extractable polymeric protein. Heat stress during grain filling was associated with a high proportion of gliadin and low proportions of the polymeric protein in the grain. However, the proportions of gliadin and of SDS-extractable polymeric protein were less affected by high temperatures in grain with high Zn concentrations. The results demonstrate that Zn nutrition can alter protein composition and the effects of Zn may interact with grain filling temperatures.

Dietary change in Micronesia has led to serious problems of vitamin A deficiency and other nutritionally-related health problems. It is essential to identify nutrient-rich indigenous foods that may be promoted for health improvements. Giant swamp taro (Cyrtosperma merkusii) is important for food and culture on atoll and mountainous islands of Micronesia. There are many Cyrtosperma cultivars, but few have been analyzed for nutrient content. Samples were collected in the Federated States of Micronesia (Pohnpei, Chuuk and Yap) and the Republic of Palau, assessed for corm flesh color and other attributes, and analyzed for carotenoids (β- and α-carotene, β-cryptoxanthin, lutein, zeaxanthin, and lycopene) and minerals (including iron, zinc, and calcium). Of 34 cultivars analyzed, β-carotene concentrations varied from 50 to 4486 μg/100 g. Yellow-fleshed cultivars generally contained higher carotenoid concentrations. Of the ten cultivars analyzed for mineral content (wet weight basis), substantial concentrations of zinc (5.4-46.1 mg/100g), iron (0.3-0.8 mg/100 g) and calcium (121-305 mg/100 g) were found. All cultivars were acceptable for taste and production factors. These carotenoid- and mineral-rich cultivars should be considered for promotion in Micronesia and other areas for potential health benefits.

Increasing the grain zinc (Zn) concentration of staple food crops will help alleviate chronic Zn deficiency in many areas of the world. Significant variation in grain Zn concentration is often reported among collections of cereals, but frequently there is a concomitant variation in grain yield. In such cases grain Zn concentration and grain yield are often inversely related. Without considering the influence of the variation in grain yield on Zn concentration, the differences in grain Zn concentration may simply represent a yield dilution effect. Data from a series of field and glasshouse experiments was used to illustrate this effect and to describe an approach that will overcome the yield dilution effect. In experiments with a wide range of bread wheat, synthetic hexaploids and accessions of durum wheat, variation in grain yield among the genotypes accounted for 30–57% of the variation in grain Zn concentration. Variation in kernel weight also occurred, but was poorly correlated with grain Zn concentration. To account for the influence of variation in grain yield on grain Zn concentration grain Zn yield was plotted against grain yield. By defining the 95% confidence belt for the regression genotypes that have inherently low or high grain Zn concentrations at a given yield level can be identified. This method is illustrated using two data sets, one consisting of bread wheat and one comprising a collection of synthetic hexaploids.

The development of rice (Oryza sativa L.) cultivars with a higher Zn content in their grains has been suggested as a way to alleviate Zn malnutrition in human populations subsisting on rice in their daily diets. This study was conducted to evaluate the effects of native soil Zn status and fertilizer application on Zn concentrations in grains of five rice genotypes that had previously been identified as either high or low in grain Zn. Genotypes were grown in field trials at four sites ranging in native soil-Zn status from severely deficient to high in plant available Zn. At each site a −Zn plot was compared to a +Zn plot fertilized with 15 kg Zn ha−1. Results showed that native soil Zn status was the dominant factor to determine grain Zn concentrations followed by genotype and fertilizer. Depending on soil-Zn status, grain Zn concentrations could range from 8 mg kg−1 to 47 mg kg−1 in a single genotype. This strong location effect will need to be considered in estimating potential benefits of Zn biofortification. Our data furthermore showed that it was not possible to simply compensate for low soil Zn availability by fertilizer applications. In all soils fertilizer Zn was taken up as seen by a 50–200% increase in total plant Zn content. However, in more Zn deficient soils this additional Zn supply improved straw and grain yield and increased straw Zn concentrations by 43–95% but grain Zn concentrations remained largely unchanged with a maximum increase of 6%. Even in soils with high Zn status fertilizer Zn was predominantly stored in vegetative tissue. Genotypic differences in grain Zn concentrations were significant in all but the severely Zn deficient soil, with genotypic means ranging from 11 to 24 mg kg−1 in a Zn deficient soil and from 34 to 46 mg kg−1 in a high Zn upland soil. Rankings of genotypes remained largely unchanged from Zn deficient to high Zn soils, which suggests that developing high Zn cultivars through conventional breeding is feasible for a range of environments. However, it may be a challenge to develop cultivars that respond to Zn fertilizer with higher grain yield and higher grain Zn concentrations when grown in soils with low native Zn status.

Four semi-quantitative screening methods were developed for plant breeding purposes to identify iron (Fe) and zinc (Zn)-dense genotypes in germplasm, elite lines and early generation progeny. Methods include colour image analysis for Fe and Zn in wheat and rice grains, and spectrophotometric analysis of Fe and Zn in ground flour of rice, wheat, potato, sweet potato and cassava. Staining with 71 mM Perl's Prussian blue solution (PPB) and subsequent image analysis with Adobe Photoshop® to determine pixel numbers in the stained regions lead to the quantification of Fe. Due to differences in grain size between the genotypes evaluated, correlations between inductively coupled plasma-optical emission spectrophotometry (ICP-OES) Fe and PPB derived Fe were improved by standardizing according to grain weight. The ratio of total blue pixel number (TPN)/total grain weight (TGW) of 21 rice lines correlated (r=0.84, p

The world’s rare selenium resources need to be managed carefully. Selenium is extracted as a by-product of copper mining and there are no deposits that can be mined for selenium alone. Selenium has unique properties as a semi-conductor, making it of special value to industry, but it is also an essential nutrient for humans and animals and may promote plant growth and quality. Selenium deficiency is regarded as a major health problem for 0.5 to 1 billion people worldwide, while an even larger number may consume less selenium than required for optimal protection against cancer, cardiovascular diseases and severe infectious diseases including HIV disease. Efficient recycling of selenium is difficult. Selenium is added in some commercial fertilizers, but only a small proportion is taken up by plants and much of the remainder is lost for future utilization. Large biofortification programmes with selenium added to commercial fertilizers may therefore be a fortification method that is too wasteful to be applied to large areas of our planet. Direct addition of selenium compounds to food (process fortification) can be undertaken by the food industry. If selenomethionine is added directly to food, however, oxidation due to heat processing needs to be avoided. New ways to biofortify food products are needed, and it is generally observed that there is less wastage if selenium is added late in the production chain rather than early. On these bases we have proposed adding selenium-enriched, sprouted cereal grain during food processing as an efficient way to introduce this nutrient into deficient diets. Selenium is a non-renewable resource. There is now an enormous wastage of selenium associated with large-scale mining and industrial processing.We recommend that this must be changed and that much of the selenium that is extracted should be stockpiled for use as a nutrient by future generations.Key words: selenium, essential nutrient, deficiency, fertilizer, food processing

Iron deficiency is the most prevalent nutritional deficiency, affecting more than 30% of the total world's population. It is a major public health problem in many countries around the world. Over the years various methods have been used with an effort to try and control iron-deficiency anemia. However, there has only been a marginal reduction in the global prevalence of anemia. Why is this so? Iron and zinc are essential trace elements for humans. These metals influence the transport and absorption of one another across the enterocytes and hepatocytes, due to similar ionic properties. This paper describes the structure and roles of major iron and zinc transport proteins, clarifies iron-zinc interactions at these sites, and provides a model for the mechanism of these interactions both at the local and systemic level. This review provides evidence that much of the massive extent of iron deficiency anemia in the world may be due to an underlying deficiency of zinc. It explains the reasons for predominance of cellular zinc status in determination of iron/zinc interactions and for the first time thoroughly explains mechanisms by which zinc brings about these changes.

Phytate (inositol-hexa-phosphate) has an important role in plants but it also may have anti-nutritional properties in animals and humans. While there is debate within the plant breeding and nutrition communities regarding an optimum level in grain, there appears to be little information at the molecular level for the genetics of this trait, and its association with important trace elements, in particular, Fe and Zn. In this preliminary study, quantitative trait loci (QTL) for grain phytates, Zn and Fe in glasshouse-grown rice lines from an IR64 x Azucena doubled haploid population were identified. Correlations between phytate and essential nutrients were also studied. Transgressive segregation was found for most traits. Phytate and total P concentrations had one QTL in common located on chromosome five with the (high concentration) allele contributed from Azucena. There were significant positive correlations between phytate and inorganic phosphorus (P), total P, Fe, Zn, Cu and Mn concentrations for both grain concentration and content. However, the QTLs of phytate were not located on the same chromosomal regions as those found for Fe, Zn and Mn, suggesting that they were genetically different and thus using molecular markers in breeding and selection would modify the phytate level without affecting grain micronutrient density.

Zinc (Zn) has a vast number of functions in plant metabolism and consequently Zn deficiency has a range of effects on plant growth. There are a number of different possible mechanisms by which plants tolerate Zn deficiency (generally expressed as Zn efficiency), such as Zn uptake, translocation to the shoot and physiological efficiency. However, there have been no direct comparisons of the relative importance of these possible mechanisms of Zn efficiency in a large set of genotypes of contrasting Zn efficiency. Soil and solution culture studies were conducted to examine the relative contribution of different mechanisms of Zn efficiency at the whole plant level in bread and durum wheat during early vegetative stage. Zn treatments were 0, 0.05, 0.1 and 1 mg/kg soil in the soil culture, and nil in the solution culture. Visual symptoms of Zn deficiency, dry matter production, Zn uptake, Zn distribution between roots and shoots, Zn utilization in roots and shoots and Zn remobilisation from the seed into growing parts were examined. Significant genotypic differences were observed in most criteria and responses differed with external Zn supply. The results of the present study suggest that while there are a number of different mechanisms contributing to Zn efficiency, uptake is the major mechanism and the effect of this is modified by the physiological efficiency within the shoot. Root:shoot partitioning was not strongly associated with Zn efficiency and seed Zn remobilisation was not linked to Zn efficiency. Visual symptoms of the severity of Zn deficiency was a good predictor of Zn efficiency and was correlated with Zn uptake.

A randomized double-blind placebo-controlled study was conducted in children admitted to hospital with gastroenteritis (≥3 loose stools per day). All were treated for 5 days following admission with either zinc (Zn, 3 mg) or without Zn-fortified rice-based oral rehydration solution (ORS). 13C-sucrose breath test (SBT) and intestinal permeability (lactulose/rhamnose or L/R ratio) were performed concurrently prior to commencement of ORS with or without Zn and at day 5 post-admission. There was a significant improvement in the SBT results in both the Zn-fortified group, median (5th-95th percentile) 2.1% (0.4% to 8.3%) versus 4.4% (0.4% to 10.4%), P < .05, and control group, 1.4% (0.1% to 5.4%) versus 4.3% (0.4% to 11.4%), P < .05, between the day of admission and day 5 post-admission. In the Zn-fortified group, there was also a significant improvement in L/R ratio between the day of admission and day 5 post-admission, 53.0 (19.5-90.6) versus 17.7 (13.4-83.2), P < .05. Low levels of Zn improved intestinal permeability but did not enhance short-term recovery following diarrheal illness.

More than 2 billion people consume diets that are less diverse than 30 years ago, leading to deficiencies in micronutrients, especially iron (Fe), zinc (Zn), selenium (Se), iodine (I), and also vitamin A. A strategy that exploits genetic variability to breed staple crops with enhanced ability to fortify themselves with micronutrients (genetic biofortification) offers a sustainable, cost-effective alternative to conventional supplementation and fortification programs. This is more likely to reach those most in need, has the added advantages of requiring no change in current consumer behaviour to be effective, and is transportable to a range of countries. Research by our group, along with studies elsewhere, has demonstrated conclusively that substantial genotypic variation exists in nutrient (e.g. Fe, Zn) and nutrient promotor (e.g. inulin) concentrations in wheat and other staple foods. A rapid screening technique has been developed for lutein content of wheat and triticale, and also for pro-vitamin A carotenoids in bread wheat. This will allow cost-effective screening of a wider range of genotypes that may reveal greater genotypic variation in these traits. Moreover, deeper understanding of genetic control mechanisms and development of molecular markers will facilitate breeding programs. We suggest that a combined strategy utilising plant breeding for higher micronutrient density; maximising the effects of nutritional promoters (e.g. inulin, vitamin C) by promoting favourable dietary combinations, as well as by plant breeding; and agronomic biofortification (e.g. adding iodide or iodate as fertiliser; applying selenate to cereal crops by spraying or adding to fertiliser) is likely to be the most effective way to improve the nutrition of populations. Furthermore, the importance of detecting and exploiting beneficial interactions is illustrated by our discovery that in Fe-deficient chickens, circulating Fe concentrations can be restored to normal levels by lutein supplementation. Further bioavailability/bioefficacy trials with animals and humans are needed, using varying dietary concentrations of Fe, Zn, carotenoids, inulin, Se and I to elucidate other important interactions in order to optimise delivery in biofortification programs.

Selenium (Se) is an essential micronutrient for humans and animals, with antioxidant, anti-cancer and anti-viral effects, and wheat is an important dietary source of this element. In this study, surveys of Se concentration in grain of ancestral and wild relatives of wheat, wheat landrace accessions, populations, and commercial cultivars grown in Mexico and Australia were conducted. Cultivars were also grown under the same conditions to assess genotypic variation in Se density. Eleven data sets were reviewed with the aim of assessing the comparative worth of breeding compared with fertilising as a strategy to improve Se intake in human populations. Surveys and field trials that included diverse wheat germplasm as well as other cereals found grain Se concentrations in the range 5–720μgkg−1, but much of this variation was associated with spatial variation in soil selenium. This study detected no significant genotypic variation in grain Se density among modern commercial bread or durum wheat, triticale or barley varieties. However, the diploid wheat, Aegilops tauschii and rye were 42% and 35% higher, respectively, in grain Se concentration than other cereals in separate field trials, and, in a hydroponic trial, rye was 40% higher in foliar Se content than two wheat landraces. While genotypic differences may exist in modern wheat varieties, they are likely to be small in comparison with background soil variation, at least in Australia and Mexico. Field sites that are spatially very uniform in available soil Se would be needed to allow comparison of grain Se concentration and content in order to assess genotypic variation.

This study investigated the main factors contributing to boron toxicity in plants. Growth was rapidly inhibited by internal B concentrations in the range 1–5 m m across a range of plant types that included monocot, dicot and algal species. In contrast, mature cells were able to withstand up to 60 m m B for several days. In wheat, rapid inhibition of root growth occurred if high B was applied to the root tip, but not if high B was applied to mature sections of the root. In leaves, there were gradations in B concentrations that correlated with visible symptoms of toxicity. However, there was no evidence to support the hypothesis that toxicity in leaves is due to osmotic stress induced by the accumulation of B. Analysis of the sensitivity to B of a range of metabolic processes including photosynthesis, respiration and protein synthesis leads to the conclusion that growth is not restricted by effects of B on energy supply and not directly by inhibition of protein synthesis. At higher B concentrations, many cellular activities were found to be partially inhibited and the toxicity to mature tissues was therefore considered not to arise from the disruption of a single process, but from the accumulated retardation of many cellular processes, exacerbated in light by photo-oxidative stress.

Whole-meal wheat, including both bread and durum varieties, and triticale samples were analysed for their carotenoid content by HPLC, and colour using reflectance spectrophotometry (CIE L*a*b*). A positive correlation between CIE b* (yellowness) and lutein concentration was shown in all wheat groups but was strongest in the durums. There was little correlation between CIE L* (lightness) or CIE a* (redness) and lutein, alpha- or beta-carotene. In contrast, the b* value correlated well with the concentration of alpha- and beta-carotene, and therefore the vitamin A activity, though those wheat groups that did not have a strong correlation were those with the lowest CIE b* values. The durum wheat group had the highest CIE b* value and the highest lutein concentration but a relatively low concentration of beta-carotene.

Considerable genetic variation exists in zinc (Zn) efficiency among cereal species and genotypes within the same species. Currently, the mechanisms of Zn efficiency are not understood well; however, the research so far suggests that overall Zn efficiency can be partitioned into uptake, utilisation and translocation or remobilisation efficiency, all or some of which collectively determine the level of Zn efficiency in a particular genotype. In a growth room study, using two barley genotypes differing in Zn efficiency (Zn-efficient Unicorn and Zn-inefficient Amagi Nijo), we attempted to determine which of these components of Zn efficiency contributed to greater Zn efficiency in Unicorn, by examining growth responses to Zn over a wide range of Zn fertilisation rates (0, 0.05, 0.2, 0.8, 3.2 and 12.8 mg Zn/kg soil) during the entire growth period. Zn-efficient Unicorn showed less severe Zn deficiency symptoms, produced more dry matter, and grain yield under Zn deficient conditions compared with Zn-inefficient Amagi Nijo. These responses also varied with the level of Zn deficiency stress and growth stage. Most importantly, the greater Zn efficiency (e.g., ability to grow well under Zn deficiency) at maturity of Unicorn was due to greater translocation of Zn from vegetative to reproductive organs or greater ability to produce higher grain yield with limited Zn rather than Zn uptake from soil which was similar in both genotypes. Zn-efficient Unicorn also had a lower critical deficiency concentration for grain (12 mg Zn/kg DW) than the Zn-inefficient Amagi Nijo (18 mg Zn/kg DW), suggesting a lower requirement for metabolic processes in Zn-efficient Unicorn. The critical deficiency concentration in the grain has the potential to diagnose Zn-deficient soils. The results also show that grain Zn concentration can be increased by Zn fertilisation, with significant increases occurring above the Zn fertilisation rate that is adequate for production of grain. However, genetic variation in grain Zn concentration should be explored and wild relatives of barley may offer potential for crop improvement for this trait.

Biofortification of staple food crops with micronutrients by either breeding for higher uptake efficiency or fertilization can be an effective strategy to address widespread dietary deficiency in human populations. Selenium and iodine deficiencies affect a large proportion of the population in countries targeted for biofortification of staple crops with Zn, Fe, and vitamin A, and inclusion of Se and I would be likely to enhance the success of these programs. Interactions between Se and I in the thyroid gland are well established. Moreover, Se appears to have a normalizing effect on certain nutrients in the body. For example, it increases the concentration of Zn and Fe at key sites such as erythrocytes when these elements are deficient, and reduces potentially harmful high Fe concentration in the liver during infection. An important mechanism in Se/Zn interaction is selenoenzyme regulation of Zn delivery from metallothionein to Zn enzymes. More research is needed to determine whether sufficient genetic variability exists within staple crops to enable selection for Se and I uptake efficiency. In addition, bioavailability trials with animals and humans are needed, using varying dietary concentrations of Se, I, Zn, Fe, and vitamin A to elucidate important interactions in order to optimize delivery in biofortification programs.

Biofortification of staple food crops with micronutrients by either breeding for higher uptake efficiency or fertilization can be an effective strategy to address widespread dietary deficiency in human populations. Selenium and iodine deficiencies affect a large proportion of the population in countries targeted for biofortification of staple crops with Zn, Fe, and vitamin A, and inclusion of Se and I would be likely to enhance the success of these programs. Interactions between Se and I in the thyroid gland are well established. Moreover, Se appears to have a normalizing effect on certain nutrients in the body. For example, it increases the concentration of Zn and Fe at key sites such as erythrocytes when these elements are deficient, and reduces potentially harmful high Fe concentration in the liver during infection. An important mechanism in Se/Zn interaction is selenoenzyme regulation of Zn delivery from metallothionein to Zn enzymes. More research is needed to determine whether sufficient genetic variability exists within staple crops to enable selection for Se and I uptake efficiency. In addition, bioavailability trials with animals and humans are needed, using varying dietary concentrations of Se, I, Zn, Fe, and vitamin A to elucidate important interactions in order to optimize delivery in biofortification programs.

Genetic improvement of manganese efficiency of crops demands a precise bioassay that avoids the confounding effect of seed manganese on the bioassay for the trait, for a proper comparison of the genotypes the seed manganese content must be similar. Variation in seed manganese can be minimized by the addition of manganese to individual seeds to be planted providing the effect of seed manganese content on early growth and development for the chosen genotype has been determined. It was hypothesized that growing the plants as mono-culms in very small pots under subclinical manganese deficiency would limit grain yield and yield attribute among genotypes, resulting in seed with less variation in manganese content across genotypes. The effect on yield and components of soil fertility ranging from University of California (UC) potting mix, fortified with Osmocote, to 100% manganese-deficient calcareous sand from Wangary, South Australia (Psamment) was determined for 20 bread wheat genotypes and breeding ...

A growth room study was conducted to compare responses to zinc of two barley (Hordeum vulgare L. cw. Tarm and Hamidiye) genotypes differing in zinc (Zn) efficiency and to determine a critical deficiency concentration of Zn in tissue. Two genotypes of barley, Tarm (Zn efficient) and Hamidiye (Zn inefficient), were grown in a Zn deficient siliceous sand with Zn added at 10 Zn rates (0, 0.04, 0.08, 0.1, 0.2, 0.4, 0.8, 1.6, 3.2, and 6.4 mg Zn/kg dry soil). Visual Zn deficiency symptoms, such as inhibition of shoot elongation and development of chlorotic areas on leaves, appeared more rapidly and severely in Hamidiye when Zn supply was deficient (

Background Biofortification of staple crops with essential micronutrients relies on the efficient, long distance transport of nutrients to the developing seed. The main route of this transport in common wheat (Triticum aestivum) is via the phloem, but due to the reactive nature of some essential micronutrients (specifically Fe and Zn), they need to form ligands with metabolites for transport within the phloem. Current methods available in collecting phloem exudate allows for small volumes (μL or nL) to be collected which limits the breadth of metabolite analysis. We present a technical advance in the measurement of 79 metabolites in as little as 19.5 nL of phloem exudate. This was achieved by using mass spectrometry based, metabolomic techniques. Results Using gas chromatography–mass spectrometry (GC-MS), 79 metabolites were detected in wheat phloem. Of these, 53 were identified with respect to their chemistry and 26 were classified as unknowns. Using the ratio of ion area for each metabolite to the total ion area for all metabolites, 39 showed significant changes in metabolite profile with a change in wheat reproductive maturity, from 8–12 to 17–21 days after anthesis. Of these, 21 were shown to increase and 18 decreased as the plant matured. An amine group derivitisation method coupled with liquid chromatography MS (LC-MS) based metabolomics was able to quantify 26 metabolites and semi-quantitative data was available for a further 3 metabolites. Conclusions This study demonstrates that it is possible to determine metabolite profiles from extremely small volumes of phloem exudate and that this method can be used to determine variability within the metabolite profile of phloem that has occurred with changes in maturity. This is also believed to be the first report of the presence of the important metal complexing metabolite, nicotianamine in the phloem of wheat.

The effect of Zn fertilisation on tolerance of Medicago truncatula to infection by the root-rotting pathogen Rhizoctonia solani (AG 8) was studied in a field survey and in two experiments in controlled conditions. From the field survey, the concentration of Zn in the shoots of medics was found to be inversely related to the severity of disease on the root. Overall, the addition of Zn to Zn-deficient soil in controlled environment experiments resulted in reduced yield loss in the presence of R. solani, a reduction in disease score and no change in the concentration of nutrients in the shoots. However, under Zn deficiency, increasing levels of added R. solani resulted in significant yield loss, an increase in disease score and a reduction in concentration of Zn in the roots. This occurred despite a decrease in the number of infection sites caused by the fungus on the root and a lower amount of R. solani DNA extracted in medics deficient in Zn compared with plants supplied with Zn. While plants supplied with Zn were able to maintain a stable concentration of Zn in the shoots, the concentration of Zn in the roots also declined with increasing levels of R. solani. In conclusion, Zn application does not directly inhibit infection by R. solani, nor reduce its pathogenicity, but it does strongly increase root growth. The net result is that Zn-sufficient plants are more tolerant to the effects of root pruning by the fungus than Zn-deficient plants.

Nineteen annual Medicago genotypes from eight species were grown in Mt. Compass sand at three levels of soil Zn application (0, 0.1 and 0.9 mg Zn kg-1) to achieve Zn status from deficiency to adequacy. Genotypes differed in growth response: under Zn deficiency, those classified as Zn-efficient had less reduction in shoot growth, a higher root mass, greater concentration of Zn in the shoot and total Zn content per plant, and a stable shoot/root ratio compared with Zn-inefficient genotypes. While seed Zn content did not influence the Zn-efficiency ranking, it did affect yield, and so it plays an important role in yield response and Zn accumulation as Zn supply decreases.

Three nutrients, iron, zinc and pro-vitamin A, are widely deficient in humans, especially among low socioeconomic groups in developing countries, but they remain significant concerns in industrialized countries as well. Cereals provide the majority of the intake of these nutrients in low-income families. Moreover, these three nutrients may interact synergistically in absorption and function to such an extent that there are potentially huge advantages in providing all three together in the one staple food. Because of this, they may be more bioavailable to deficient individuals than current thinking allows. To do so would provide a sound basis on which to build a better balanced diet for nutritionally compromised individuals. Genetic variation in nutrient composition exists in cereals and can be exploited in conventional breeding programmes and through gene technology. Cultural techniques, including fertiliser technology and organic farming, have also impacted upon the nutrient composition of cereals. Human iron and zinc intake can be doubled at least, and essential carotenoid intakes can be increased dramatically. Preliminary feeding trials with nutrient-dense grains have been encouraging. Moreover, nutrient-dense seeds also produce more vigorous seedlings and higher grain yield in soils where these nutrients are poorly available, so that to a significant extent agronomic and health objectives coincide. New varieties are rapidly adopted, especially where there are yield advantages, ensuring maximum impact without new inputs. This approach is potentially more sustainable than fortification and supplementation programmes because intake is continuous, which is especially important for zinc because it is needed almost daily.

Whether due to the genotype or the environment of the mother plant, the nutrient content of seeds vary over a wide range; the amount of the nutrient contributes greatly to seedling vigor, especially on deficient soils and may result in major differences in grain yield. This effect has important implications for breeding programs. This paper examines the impact of seed manganese (Mn) on screening of durum wheats for tolerance to Mn‐deficient soils. Seed stocks with a range of Mn contents (0.4–2.4 μg seed‐1) were produced, and the effect on expression of Mn efficiency measured as either relative yield or shoot Mn content for two durum wheat (Triticum turgidum L. var. durum) genotypes differing in Mn efficiency. Both genotypes responded to seed Mn content in terms of enhanced root and shoot growth; there was no genotype by seed Mn interaction, so Mn provided in seed was utilized additively by both Mn‐efficient and Mn‐inefficient genotypes. Manganese efficiency, measured as relative yield, was a func...

Whereas a generation ago, global starvation was the primary fear of agricultural strategists, now when food supplies are generally adequate, the World Health Organisation (WHO) has expressed increasing concern at the rise in incidence of micronutrient deficiencies in human populations in many countries. These deficiencies limit the physical and intellectual capacity of people, thereby restraining national development efforts, and adversely affecting the health and wellbeing of over half of the planet's human population. This nutritional crisis is likely to continue for the foreseeable future unless food systems are changed in ways that increase nutrient output and balance. Agriculture must deliver enough nutrients to sustain healthy and productive lives as well as focus on providing enough “food” to prevent starvation. Plant nutritionists and analysts need to understand the changes in order to play a part in planning sustainable food systems for tomorrow. The impact on analytical laboratories ass...

In the search for genetic material with high iron and zinc concentration in wheat grain, a significant positive correlation has been found between iron and zinc concentrations, suggesting that these two traits may be combined relatively easily during breeding. In future research, the very high values of iron and zinc in the grain seen in wild types and landraces need to be confirmed in trials in which all the best material is planted in the same location and year. In addition, it is important to determine if these high levels of iron and zinc in the grain can be maintained in high-yielding material. The production of semi-dwarf wheat through the introduction of the rht genes has resulted in substantial yield increases. However, this is associated with a reduction in iron and zinc concentrations in some bread wheat genotypes, but not in durum wheat. The presence of the 1B/1R translocation in the wheat germplasm of the Centro Internacional de Mejoramiento de Maiz y Trigo (CIMMYT) to increase leaf rust resistance may have had a positive effect on the concentration of iron and zinc, but a negative effect was ruled out. There is a strong positive correlation between grain yield and year of release in the CIMMYT wheat varieties. There is a small negative but statistically significant relationship between the time of release and the concentrations of iron, zinc, total phosphorus, and phytate. The positive effect of nitrogen applications on iron and zinc concentrations is more important than declines in these concentrations due to breeding during the last 42 years

Micronutrient malnutrition currently affects over 2 billion people worldwide. Poor health, low worker productivity, high rates of mortality and morbidity, increased rates of chronic diseases (coronary heart disease, cancer, stroke, and diabetes), and permanent impairment of cognitive abilities of infants born to micronutrient-deficient mothers are all consequences of micronutrient malnutrition. Furthermore, these deficiencies are contributing to lethargic national development efforts, continued high population growth rates, and a vicious cycle of poverty for massive numbers of underprivileged people in all nations. Food systems globally are not providing enough balanced nutrient output to meet all the nutritional needs of every person, especially resource-poor women, infants, and children in developing countries. Agriculture is partly responsible. It has never made adequate and balanced nutrient output an explicit goal of its production systems. Many agricultural policies may have fostered a decline in nutrition and diet diversity for the poor during the past four decades. Additionally, the nutrition and health communities have never considered using agriculture as a primary tool in their programmes directed at alleviating poor nutrition and ill health globally. A new paradigm for agriculture and nutrition is now needed. We must consider ways that agriculture can contribute to finding sustainable solutions to food system failures through holistic food-based system approaches, thereby closely linking agricultural production to improving human health, livelihood, and well-being. Such action will rouse support for agricultural research worldwide, because it addresses consumer issues as well as agricultural production issues and is, therefore, politically supportable.

As part of the Consultative Group on International Agricultural Research (CGIAR) Micronutrients Project, we have investigated the content of carotenoids in staple foods, particularly wheat. Wheat varies widely in carotenoid content, depending on the variety and type. Durum (pasta) wheat is generally higher in carotenoid content, because the market has continued to demand strong pigment in pasta and noodle products, whereas in bread wheat the market demands flour as white as possible. Consequently, twentieth-century wheat breeders have consciously selected wheat varieties low in carotenoid content, although older, high-carotenoid bread wheats are still available and the trait is not lost. The entire carotenoid biosynthetic pathway exists in wheat grains, so varieties high in β-carotene and/or other carotenoids can be reintroduced if and when education in nutrition creates the demand. Numerous high-yielding maize varieties high in β-carotene already exist and have been used to eliminate vitamin A deficiency in livestock. A β-carotene–rich rice has been genetically engineered recently. Although the carotenoid content of beans has not yet been explored, high–β-carotene lines of cassava exist, and the trait is easily handled in a breeding programme. Yellow types of most staples are known, for example, sorghum, potatoes, and sweet potatoes. The amounts present are such that we can assert that vitamin A deficiency could easily be eliminated globally by delivering the required amounts via food staples. Moreover, there are strong signs that other benefits in eye health, enhanced absorption of iron from non-haem sources, anticarcinogenic effects, enhanced aroma, and better storage life may also result.

The general objective of the Consultative Group on International Agricultural Research (CGIAR) Micronutrients Project is to assemble the package of tools that plant breeders will need to produce mineral- and vitamin-dense cultivars. The target crops are rice, wheat, maize, phaseolus beans, and cassava. The target micronutrients are iron, zinc, and vitamin A. The combining of benefits for human nutrition and agricultural productivity, resulting from breeding staple food crops that are more efficient in the uptake of trace minerals from the soil and that load more trace minerals into their seeds, results in extremely high ex ante estimates of benefit–cost ratios for investments in agricultural research in this area. This finding derives from the confluence of several complementary factors. The rates of micronutrient malnutrition are high, as are the consequent costs to human welfare and economic productivity. High trace mineral density in seeds produces more viable and vigorous seedlings, and efficiency in the uptake of trace minerals improves disease resistance. Trace-mineral-“deficient” soils in fact contain high amounts of trace minerals that are “unavailable” to staple crop varieties presently grown. Adoption of nutritionally improved varieties by farmers can rely on profit incentives; delivery to consumers can rely on existing demand behaviour. Relatively small investments in agricultural research at a central research location may be disseminated widely. Breeding advances are derived from initial, fixed costs, with low recurring costs. The encouraging research results obtained to date under the project would seem to justify a much expanded effort in the future.

The level of genotypic variation in tolerance to low boron (B) supply was investigated in solution culture grown, 10 day old (D10) oilseed rape (Brassica napus L.) plants, by using a rapid screening technique whereby root length, root elongation rate and total root dry weight were used to indicate plant response to B. Root length proved more reliable in determining genotype responses, and was used to characterise a total of 61 genotypes, of which Huashuang 2, Nangchang rape, Huashuang 1 and Zhongyou 821, and to a lesser extent, Zheyou 2, Dunkeld, Xinza 2, Nangjin 2051, 92-58, 92-13, and Awassa 115 exhibited some form of tolerance to low B supply. The genotypic rankings based on this early vegetative response corroborated with field based B-efficiency. The results demonstrate the expression of the B-efficiency mechanism in the early vegetative stages of plant growth, and establish the value of root length as a selection criterion for B-efficiency in oilseed rape.

In 1992 the International Rice Research Institute (IRRI) began to examine the effect of certain soil characteristics on the iron content of rice grains. As part of the Consultative Group for International Agricultural Research (CGIAR) Micronutrients Project, this effort was expanded in 1995 to include analysis of both iron and zinc, in collaboration with the University of Adelaide in Australia. Since then, germplasm screening has shown large genetic variation for iron and zinc concentrations in brown rice. Common cultivars contain about 12 mg of iron and 25 mg of zinc per kilogram. Some traditional varieties have double these amounts. Genetic-by-environmental interactions are sufficiently moderate that breeding for higher iron and zinc content is considered worthwhile. The next major research step will be to further study the genetics of trace mineral accumulation in the grain to determine the best selection techniques for use in breeding. High iron and zinc traits can be combined with improved agronomic traits. This has already been demonstrated in the serendipitous discovery in the IRRI testing programme of an aromatic variety (IR68144-3B-2-2-3) that has a high concentration of grain iron, about 21 mg/kg in brown rice. This elite line has good tolerance to rice tungro virus and to mineral-deficient soils and has excellent grain qualities. The yields are about 10% below those of IR72, but in partial compensation, maturity is earlier. After 15 minutes of polishing, IR68144-4B-2-2-3 had about 80% more iron than IR64, a widely grown commercial variety. It remains to be shown that this extra iron can improve the iron status of iron-deficient human subjects. A human feeding trial is being planned.

Boron (B) efficiency of oilseed rape (Brassica napus) and mustard (B. juncea) genotypes was determined on a low B soil at Mt. Compass, South Australia. B efficiency was observed in oilseed rape genotypes, Zhongyou 821, Dunkeld and Zheyou 2, and in mustard genotypes Pusa Bold and CSIRO 6. Genotypes grown in the field were also grown under glass-house conditions, in pots filled with pre-washed sand extracted from the Mt. Compass field site. Two B treatments, one B adequate (0.25 mg B kg−1 soil) and one B deficient (imposed by omission) were used to indicate whether vegetative response to B could predict final yield response and provide a more convenient selection criterion for identifying B-efficient germplasm. Vegetative response of 35 d old (D35) genotypes grown in pot culture closely reflected field response, indicating the expression of B efficiency traits in early growth, and its potential use in selection.

Grains of wheat were produced with differing zinc (Zn) or manganese (Mn) contents by culturing detached ears from anthesis onwards in solutions of four different concentrations of Zn or Mn (0.1,1.0,10, and 50 μM). After 20 days, ears were labeled with 65Zn or 54Mn at (i) the pretreatment concentrations of Zn or Mn, or (ii) at 10 μM Zn or Mn regardless of the pretreatment. Accumulation of Zn or Mn in the grain was greater as the pretreatment concentration of Zn or Mn increased from 1.0 to 10 μM, however, accumulation was less in ears cultured at 50 μM Zn or Mn. Accumulation of Mn in grain of different Mn status labeled at 10 μM Mn was similar in the 0.1,1.0, and 10 μM Mn pretreatments, but accumulation in the grain pretreated at 50 μM Mn was reduced. In contrast, accumulation of Zn in grains of different Zn status when labeled at 10 uM Zn was highest in ears pretreated at 10 μM Zn, but substantially lower in ears of a lower Zn status (those pretreated at 0.1 or 1.0 μM Zn) as well as in those pretr...

Current and past efforts in breeding for industrial quality (processing, malting, baking, extruding, etc.), as opposed to yield, are reviewed as a prelude to discussion of the criteria that need to be met in breeding programs to improve the nutritional quality of crops for human consumption. In field crops, almost no attempts to improve nutritional value have been made. Recent studies in fact indicate that most criteria can be easily satisfied: existence of sufficient genetic variation, suitable selection methods and markers, workable heritabilities, and compelling reasons for doing so. However, establishing the efficacy in deficient human populations of elite material chosen by simple selection criteria is a major challenge that requires collaboration with human nutritionists. In some cases, developing marketing strategies for nutritionally superior types that may not – by color or other characteristics – appeal to target communities is also an issue breeders must bear in mind. Nevertheless, the fact recently established that desirable traits can be combined with high yield overcomes many obstacles. The widely demonstrated acceptance of new cultivars by farmers, in developing as well as industrialized countries, will ensure high impact of worthwhile improvements in nutritional value. To combine these new traits with high yield will increase the cost of breeding programs considerably, but the benefit–cost ratio is likely to be larger also.

Manganese (Mn) deficiency is a widespread problem on the alkaline soils, particularly for durum wheat (Triticum turgidum L. var. durum), which is more sensitive than either bread wheat or barley. The existence of considerable genetic variation in current germplasm of durum wheat (a relative yield of 58% in Stojocri 2 compared to 15% in check cv Yallaroi) and the development of a consistent selection criterion (Mn content of 35‐day‐old seedlings) has made breeding for Mn efficiency feasible. The development of Mn‐efficient durum wheat would be facilitated if the mode of inheritance was well understood. F1 hybrid, F2, and F2‐derived families from a cross between Stojocri 2 (moderately efficient) and Hazar (inefficient) were studied under controlled‐environment conditions. F1 hybrid was intermediate to the parents, indicating incomplete dominance and dependence on external Mn concentration. Analysis of 110 F2 and 220 F3 single plants (including 20 F2‐derived F3 families) showed that the observed var...

Micronutrient malnutrition (‘Hidden Hunger’) now afflicts over two billion people worldwide, resulting in poor health, low worker productivity, high rates of mortality and morbidity, increased rates of chronic diseases (coronary heart disease, cancer, stroke, and diabetes), and permanent impairment of cognitive abilities of infants born to micronutrient-deficient mothers. The consequences of food system failures include lethargic national development efforts, continued high population growth rates, and a vicious cycle of poverty for massive numbers of underprivileged people in all nations. Our food systems are failing us globally by not providing enough balanced nutrient output to meet all the nutritional needs of every person, especially resource-poor women, infants and children in developing countries. Agriculture is partly responsible because it has never held nutrient output as an explicit goal of its production systems. Indeed, many agricultural policies have fostered a decline in nutrition and diet diversity for the poor in many countries. Nutrition and health communities are also partly responsible because they have never considered using agriculture as a primary tool in their programs directed at alleviating poor nutrition and ill health globally. Now is the time for a new paradigm for agriculture and nutrition. We must consider ways in which agriculture can contribute to finding sustainable solutions to food system failures through holistic food-based system approaches, thereby closely linking agricultural production to improving human health, livelihood and well being. Such action will stimulate support for agricultural research in many developed countries because it addresses consumer issues as well as agricultural production issues and is, therefore, politically supportable. # 1999 Elsevier Science B.V. All rights reserved.

Identification of genotypic differences in micronutrient concentrations of staple food crops is essential if plant breeding strategies are to improve human mineral nutrition. The concentrations of zinc (Zn), iron (Fe), copper (Cu), and manganese (Mn) in polished grains of 285 rice (Oryza sativa L.) genotypes and the relationship between concentrations of the four micronutrient elements and concentrations of protein and lysine were examined. Significant differences (P

Root tip extension was used as a measure of wheat root response to exposure to the sulfonylurea herbicide chlorsulfuron. Plants pre-grown in low-zinc (0.2 μmZnHEDTA) solutions were placed in a perspex chamber with nutrient solution on both sides of a partition separating the root tip from the rest of the plant. The root tip was exposed to different concentrations of chlorsulfuron and observations were made during 22 h. Increasing the concentration of zinc in the solution around the root tip to 4 μmZnHEDTA did not alter root tip extension in the absence of chlorsulfuron. Significant decreases in root growth after 22 h were obtained with concentrations of 120 μg chlorsulfuron l−1and greater. Increasing the Zn concentration from 0.2 to 20 μmZnHEDTA in the nutrient solution around the root tip decreased control root growth but stimulated chlorsulfuron-treated roots to extend at the same rate as chlorsulfuron-free control plants. Adding Zn and chlorsulfuron to the more mature root parts above the root tip partition did not significantly influence root tip extension. It is concluded that chlorsulfuron inhibits wheat root growth and that increased Zn concentrations can alleviate or prevent the deleterious effects of chlorsulfuron.

The effects of varied supply of zinc (Zn) (0, 0.1, 0.2, 1.0, and 10 mg Zn kg‐1 soil) and phosphorus (P) (low P: 50 mg P kg‐1 soil and high P: 150 mg P kg‐1 soil) on vegetative growth, plant tissue Zn and P concentration and their uptake were studied in six weeks old plants of two oilseed rape (Brassica napus) genotypes (92–13, a traditional genotype from China high in both erucic acid and glucosinolate, and Xinza‐2, a hybrid from China low in erucic acid and glucosinolate) grown in Laffer sand (low in Zn and P) under controlled environmental conditions. Two oilseed rape genotypes had a differential response to Zn application. Xinxa 2 responded significantly for shoot and root dry matter only up to 0.1 mg applied Zn kg‐1 soil, while 92–13 responded up to 0.2 mg Zn kg‐1 soil. Zinc at 10 mg kg‐1 soil slightly reduced shoot dry matter and drastically reduced root dry matter of both the genotypes. Shoot and root dry matter production at 0, 0.1, 0.2, and 1 mg Zn kg‐1 soil were significantly greater und...