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Understanding the genetic basis responding to nitrogen (N) fertilization in crop production is a long-standing research topic in plant breeding and genetics. Albeit years of continuous efforts, the genetic architecture parameters, such as heritability, polygenicity, and mode of selection, underlying the N responses in maize remain largely unclear. In this study, about n = 230 maize inbred lines were phenotyped under high N (HN) and low N (LN) conditions for 2 consecutive years to obtain 6 yield-related traits. Heritability analyses suggested that traits highly responsive to N treatments were less heritable. Using publicly available SNP genotypes, the genome-wide association study (GWAS) was conducted to identify n = 237 and n = 130 trait-associated loci under HN and LN conditions, n = 164 for N-responsive (NR) traits, and n = 31 for genotype by N interaction (G × N). Furthermore, genome-wide complex trait Bayesian (GCTB) analysis, a method complementary to GWAS, was performed to estimate genetic parameters, including genetic polygenicity and the mode of selection (S). GCTB results suggested that the NR value of a yield component trait was highly polygenic and that 4 NR traits exhibited negative correlations between SNP effects and their minor allele frequencies (or the S value <0)—a pattern consistent with negative selection to purge deleterious alleles. This study reveals the complex genetic architecture underlying N responses for yield-related traits and provides candidate genetic loci for N resilient maize improvement. [ABSTRACT FROM AUTHOR]

Background and Objectives: Drying affects quality parameters of the grains. The objective of this study was to investigate effects of drying methods, moisture contents at harvesting time and corn hybrids on mechanical properties (deformation, rupture force, firmness, necessary energy and power and toughness at rupture points) and electrical conductivity of corn kernels. Materials and Methods: The study assessed four corn hybrids (Ns640, Jeta600, Konsur580 and SC704) harvested at various moisture contents (20, 30 and 40%) and dried using two drying methods (sun dried and artificially dried using oven at 85-90 oC). Results: Results revealed that corn variety significantly affected mechanical properties since Ns640 included the maximum and Konsur580 the minimum properties, compared to that other hybrids did. Furthermore, variety affected electrical conductivity. Konsur580 variety exhibited a higher electrical conductivity in both drying methods. Moisture contents at harvesting time significantly affected all mechanical properties, except deformation and firmness, in the two drying methods. Higher values of mechanical properties were achieved at 20% moisture. Moreover, effects of the moisture contents on electrical conductivity were significant and kernels with 40% moisture at harvesting time included higher electrical conductivities. Conclusions: Drying methods of corn significantly affected quality parameters and electrical conductivity. Corn kernels dried in sun included higher levels of properties such as rupture force, necessary energy and power, toughness and lower levels of electrical conductivity. [ABSTRACT FROM AUTHOR]

Transposable elements (TEs) are a ubiquitous feature of plant genomes. Because of the threat they post to genome integrity, most TEs are epigenetically silenced. However, even closely related plant species often have dramatically different populations of TEs, suggesting periodic rounds of activity and silencing. Here, we show that the process of de novo methylation of an active element in maize involves two distinct pathways, one of which is directly implicated in causing epigenetic silencing and one of which is the result of that silencing. Epigenetic changes involve changes in gene expression that can be heritably transmitted to daughter cells in the absence of changes in DNA sequence. Epigenetics has been implicated in phenomena as diverse as development, stress response, and carcinogenesis. A significant challenge facing those interested in investigating epigenetic phenomena is determining causal relationships between DNA methylation, specific classes of small RNAs, and associated changes in gene expression. Because they are the primary targets of epigenetic silencing in plants and, when active, are often targeted for de novo silencing, TEs represent a valuable source of information about these relationships. We use a naturally occurring system in which a single TE can be heritably silenced by a single derivative of that TE. By using this system it is possible to unravel causal relationships between different size classes of small RNAs, patterns of DNA methylation, and heritable silencing. Here, we show that the long terminal inverted repeats within Zea mays MuDR transposons are targeted by distinct classes of small RNAs during epigenetic silencing that are dependent on distinct silencing pathways, only one of which is associated with transcriptional silencing of the transposon. Further, these small RNAs target distinct regions of the terminal inverted repeats, resulting in different patterns of cytosine methylation with different functional consequences with respect to epigenetic silencing and the heritability of that silencing. [ABSTRACT FROM AUTHOR]

Recombinant inbred lines (RILs) are an important resource for mapping genes controlling complex traits in many species. While RIL populations have been developed for maize, a maize RIL population with multiple teosinte inbred lines as parents has been lacking. Here, we report a teosinte nested association mapping (TeoNAM) population, derived from crossing five teosinte inbreds to the maize inbred line W22. The resulting 1257 BC1S4 RILs were genotyped with 51,544 SNPs, providing a high-density genetic map with a length of 1540 cM. On average, each RIL is 15% homozygous teosinte and 8% heterozygous. We performed joint linkage mapping (JLM) and a genome-wide association study (GWAS) for 22 domestication and agronomic traits. A total of 255 QTL from JLM were identified, with many of these mapping near known genes or novel candidate genes. TeoNAM is a useful resource for QTL mapping for the discovery of novel allelic variation from teosinte. TeoNAM provides the first report that PROSTRATE GROWTH1, a rice domestication gene, is also a QTL associated with tillering in teosinte and maize. We detected multiple QTL for flowering time and other traits for which the teosinte allele contributes to a more maize-like phenotype. Such QTL could be valuable in maize improvement. [ABSTRACT FROM AUTHOR]

Production risk has been ignored in most of the analysis of GM technology, which has mostly focused on its effects on mean yield. We use stochastic dominance to quantify the effect of GM traits on the entire distribution of yields in corn in the USA under a wide range of growing conditions. Although no GM hybrid outperforms conventional hybrids under all growing conditions, we present evidence that most GM hybrids can be considered as improvements of the yield distribution. [ABSTRACT FROM AUTHOR]

In the course of generating populations of maize with teosinte chromosomal introgressions, an unusual sickly plant phenotype was noted in individuals from crosses with two teosinte accessions collected near Valle de Bravo, Mexico. The plants of these Bravo teosinte accessions appear phenotypically normal themselves and the F1 plants appear similar to typical maize × teosinte F1 s. However, upon backcrossing to maize, the BC1 and subsequent generations display a number of detrimental characteristics including shorter stature, reduced seed set, and abnormal floral structures. This phenomenon is observed in all BC individuals and there is no chromosomal segment linked to the sickly plant phenotype in advanced backcross generations. Once the sickly phenotype appears in a lineage, normal plants are never again recovered by continued backcrossing to the normal maize parent. Whole-genome shotgun sequencing reveals a small number of genomic sequences, some with homology to transposable elements, that have increased in copy number in the backcross populations. Transcriptome analysis of seedlings, which do not have striking phenotypic abnormalities, identified segments of 18 maize genes that exhibit increased expression in sickly plants. A de novo assembly of transcripts present in plants exhibiting the sickly phenotype identified a set of 59 upregulated novel transcripts. These transcripts include some examples with sequence similarity to transposable elements and other sequences present in the recurrent maize parent (W22) genome as well as novel sequences not present in the W22 genome. Genome-wide profiles of gene expression, DNA methylation, and small RNAs are similar between sickly plants and normal controls, although a few upregulated transcripts and transposable elements are associated with altered small RNA or methylation profiles. This study documents hybrid incompatibility and genome instability triggered by the backcrossing of Bravo teosinte with maize. We name this phenomenon "hybrid decay"and present ideas on the mechanism that may underlie it. [ABSTRACT FROM AUTHOR]

Abstract Zearalenone (ZEA), a mycotoxin produced by several Fusarium molds, can be found in many cereals and related products. The toxicity of ZEA has been reported for both humans and animals. Therefore, many countries have adopted regulations in foods and feed materials to limit the exposure to this contaminant. In this paper, we propose a multicommutated flow-through optosensor to quantify ZEA in different cereal samples. ZEA was retained and pre-concentrated on C 18 silica gel, and the use of the multicommutated flow manifold allowed the automated retention/desorption of ZEA on the solid microbeads by the use of appropriate carrier/eluting solutions, hence increasing the selectivity and sensitivity of the system. The native fluorescence of ZEA was recorded on the solid phase at λ exc /λ em of 265/465 nm/nm. A QuEChERS procedure was used to carry out the extraction of ZEA from different cereal samples (feedstuff materials). Recovery studies were performed to assess the accuracy of the method, obtaining recovery yields between 93% and 107% in all the analyzed samples. LC-MS was employed as reference method. The quantitation limit of the proposed method was low enough to fulfill the maximum residue levels established by the Commission of the European Communities, thus demonstrating its potential use for the analysis of ZEA in feedstuffs. Graphical abstract fx1 Highlights • Multicommutated fluorescence method for the quantification of zearalenone. • Zearalenone is quantified in maize and maize-based feed samples. • The method complies with the maximum residue limit of the European Communities. • Satisfactory comparison with an LC-MS reference method. • Alternative method for routine screening of zearalenone in cereals. [ABSTRACT FROM AUTHOR]

Phenolic compounds in foods have been widely studied due to their health benefits. In cereals, phenolic compounds are extensively linked to cell wall polysaccharides, mainly arabinoxylans, which cross-link with each other and with other cell wall components. In maize, ferulic acid is the phenolic acid present in the highest concentration, forming ferulic acid dehydrodimers, trimers and tetramers. The cross-linking of polysaccharides is important for the cell wall structure and growth, and may protect against pathogen invasion. In addition to the importance for maize physiology, ferulic acid has been recognized as an important chemical structure with a wide range of health benefits when consumed in a diet rich in fibre. This review paper presents the different ways ferulic acid can be present in maize, the importance of ferulic acid derivatives and the methodologies that can be used for their analysis. [ABSTRACT FROM AUTHOR]

Multispectral imaging with object-wise multivariate image analysis was evaluated for its potential to grade whole white maize kernels. The types of defective materials regarded in grading legislation were divided into 13 classes, and were imaged with a multispectral imaging instrument spanning the UV, visible and NIR regions (19 wavelengths ranging from 375 to 970 nm). Object-wise partial least squares discriminant analysis (PLS-DA) models were developed and validated with an independent data set. Results demonstrated good performance in distinguishing between sound maize and undesirable materials, with cross-validated coefficients of determination (Q 2 ) and classification accuracies ranging from 0.35 to 0.99 and 83 to 100%, respectively. Wavelengths related to absorbance of green, yellow and orange colour indicated the presence of lycopene and anthocyanin (505, 525, 570 and 590 nm). NIR wavelengths 890, 940 nm (associated with fat) and 970 nm (associated with water) were generally identified as important features throughout the study. [ABSTRACT FROM AUTHOR]

In this study, pot experiments were performed to investigate the effects of high temperature stress (44 °C) in maize plants colonized with and without arbuscular mycorrhizal fungi (AMF). Various parameters characterizing photosynthetic activity were measured in order to estimate the photosynthetic efficiency in maize plants. It was observed that density of active reaction centers of PSII, quantum efficiency of photosystem II (PSII), linear electron transport, excitation energy trapping, performance index, net photosynthesis rate increased in AMF (+) plants at 44 °C ± 0.2 °C. Efficiency of primary photochemical reaction (represented as F v /F o ) increased in AMF (+) plants as compared to AMF (−) plants. AMF seems to have protected water splitting complex followed by enhanced primary photochemistry of PSII under high temperature. Basic morphological parameters like leaf width, plant height and cob number increased in AMF (+) plants as compared to AMF (−) plants. AMF (+) plants grew faster than AMF (−) plants due to larger root systems. Chl content increased in AMF (+) plants as compared to AMF (−) maize plants. AMF hyphae likely increased Mg uptake which in turn increased the total chlorophyll content in AMF (+) maize plants. This subsequently led to a higher production in photosynthate and biomass. Thus AMF (+) plants have shown better photosynthesis performance as compared to AMF (−) maize plants under high temperature stress. [ABSTRACT FROM AUTHOR]

The aim was to compare the distribution of ANCs in purple and blue corn coproducts from three conventional corn fractionation processes and linking ANC partitioning in different coproducts to corn kernel phenotype. Total monomeric anthocyanin (TA) from purple corn extract was 4933.1 ± 43.4 mg cyanidin-3-glucoside equivalent per kg dry corn, 10 times more than blue corn. In dry milled purple corn, maximum ANCs were present in the pericarp (45.9% of total ANCs) and in wet-milling they were concentrated in steeping water (79.1% of total ANCs). For blue corn, the highest TA was in small grits and gluten slurry in dry-milling and wet-milling coproducts, respectively. HPLC showed the highest concentration of each ANC in steeping water for purple corn coproducts. Micrographs of kernel showed pigments concentrated in pericarp layer of purple but only in aleurone of blue corn. ANCs can concentrate in certain coproducts depending upon physical distribution of pigments in kernel. [ABSTRACT FROM AUTHOR]

A simple and rapid magnetic solid-phase extraction (M-SPE) procedure using multi-walled carbon nanotube-magnetic nanoparticles (MWCNT-MNPs) as sorbents was established for purification of zearalenone (ZEA), α-zearalenol (α-ZOL), β-zearalenol (β-ZOL), zearalanone (ZAN), α-zearalanol (α-ZAL) and β-zearalanol (β-ZAL) in maize. The main parameters affecting the clean-up efficiency were thoroughly investigated, and high purification efficiencies for all analytes were obtained. The resulting MWCNT-MNP-ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method was validated for maize samples. The matrix effects were greatly minimized using the M-SPE approach, with signal suppression/enhancement values decreased from 69.9–127.6% to 92.1–103.8%. Consequently, complex matrix-matched calibration curves were not necessary and the calibrations constructed in acetonitrile could be applied for accurate quantification of the targeted mycotoxins in real samples. The average recoveries ranged from 75.8 to 104.1% and the inter- and intra-day precision values expressed as RSDs, were all lower than 14%. Limits of detection and quantification were in the range of 0.03–0.04 and 0.07–0.10 μg/kg, respectively. The analytical performance of the developed method was also successfully evaluated with maize samples, and this method was proved to be a powerful tool for monitoring ZEA and its derivatives in maize. [ABSTRACT FROM AUTHOR]

A total of 249 maize kernel samples from 8 maize-producing provinces of China were collected after the harvest season in 2014. All samples were analysed using high-performance liquid chromatography. The incidences of FBs (FB1 + FB2) from Guizhou, Hebei, Inner Mongolia, Shanxi, Chongqing, Liaoning, Heilongjiang, and Henan provinces were 71.4%, 73.8%, 28.0%, 52.6%, 85.0%, 87.5%, 38.1%, and 100.0%, respectively. The average concentration of FBs was 817 µg kg−1and the concentrations ranged from <6 to 15,252 µg kg−1. Among the 249 maize kernel samples, 28 samples exhibited higher levels as set by the Food and Drug Administration (2000 µg kg−1), whereas 12 samples exhibited higher levels as set by the European Commission (4000 µg kg−1). The average exposure to FBs (0.12 µg kg−1body weight/day) is within the provisional maximum tolerable daily intake of 2.0 µg kg−1body weight as set by the Joint FAO/WHO Expert Committee on Food Additives. [ABSTRACT FROM AUTHOR]

Food security considerations have shifted in recent years, with the recognition that available food should also be nutritious and safe. There is a growing evidence base for contamination of maize and other crops by fungal toxins in the tropics and sub-tropics. As an initial snapshot of contamination by one of these toxins in Rwanda, Aflatoxin B1 (AFB1) was analyzed in 684 samples of maize flour collected in seven principal retail markets of Kigali and in 21 samples of animal feed from seven feed vendors. Two rounds of sample collections were carried out, the first in September 2014 and the second in January 2015. A questionnaire given to vendors was used to determine if gender and education level of vendors, origin of maize and awareness of aflatoxins had any significant effect on AFB1 level in collected samples. Enzyme-Linked Immunosorbent Assay (ELISA) and Immuno-affinity fluorimetery were used to analyze samples. Only markets had a significant effect on AFB1 level; for the two collections, differences were inconsistent among markets. In the first round, market means of AFB1 varied between 8.0 ± 5.57 μg/kg and 24.7 ± 23.74 μg/kg and for the second round, between 10.4 ± 8.4 μg/kg and 25.7 ± 25.85 μg/kg. In most animal feed samples AFB1 was >100 μg/kg. None of the vendors interviewed was aware of the risk of mycotoxin contamination in their maize-based flours and feed. Limits set by the United States Food and Drug Administration (20 μg/kg) for total aflatoxins and European Commission (2 μg/kg) for AFB1 for maize flour imports, were varied between 2–35% and 66–100% of samples, respectively. The implications of this study for human and animal health in Rwanda suggest that expanded surveys are needed to understand the scope of contamination, given the influence of environment and other factors on aflatoxin accumulation. Available options to mitigate and monitor aflatoxin contamination can be further deployed to reduce contamination. [ABSTRACT FROM AUTHOR]

Understanding the physiological changes associated with high grain yield and high N use efficiency (NUE) is important when increasing the plant density and N rate to develop optimal agronomic management. We tested the hypothesis that high plant densities resulting in crowding stress reduce the ability of plants to use the N supply post-silking, thus decreasing the grain yield and NUE. In 2013 and 2014, a field experiment, with five N-application rates and three plant densities (6.0, 7.5, and 9.0 plants m–2), was conducted in the North China Plain (NCP). The calculated maximum grain yield and agronomic use efficiency (AEN) at a density of 7.5 plants m–2 were 12.4 Mg ha–1 and 39.3 kg kg–1, respectively, which were significantly higher than the values obtained at densities of 6.0 (11.3 Mg ha–1 and 30.2 kg kg–1) and 9.0 plant m–2 (11.7 Mg ha–1 and 27.8 kg kg–1). A high plant density of 9.0 plants m–2 decreased the post-silking N accumulation, leaf N concentration and net photosynthesis, which reduced the post-silking dry matter production, resulting in a low yield and NUE. Although a relatively low grain yield was observed at a density of 9.0 plants m–2, the optimal N rate increased from 150 to 186 kg N ha-1 at a density of 7.5 plants m–2. These results indicate that high plant densities with crowding stress reduce the ability of plants to use soil N during the post-silking period, and high rate of N fertilizer was needed to increase grain yield. We conclude that selecting the appropriate plant density combined with optimal N management could increase grain yields and the NUE in the NCP. [ABSTRACT FROM AUTHOR]

Nixtamalization is a well-known pre-treatment technique in the tortilla industry. Nixtamalized maize (nixtamal) is known for its modified physicochemical as well as nutritional attributes. In the present study, two types of nixtamalization processes (traditional and ecological) were employed for the development of whole-grain-maize-based noodles using Dent and Flint maize genotypes. Results showed that ecological nixtamalization had resulted in better cooking and textural qualities of noodles compared to the one prepared traditionally. Dent maize noodles from traditional and ecological nixtamalization had lower retention of phenolics (40 and 64%, respectively) whereas, Flint maize noodles retained 50 and 66% phenolics, respectively. Dent maize noodles had undergone phenolics loss of 5–6% on cooking while those of Flint maize lost only 2%. Ecological nixtamalization maintained the pH of the cooking liquor within an acidic-neutral range and yielded noodle with higher retention of phenolics whereas, the traditional process negatively affected the antioxidant compounds and their properties. [ABSTRACT FROM AUTHOR]

Aflatoxins are a group of carcinogenic compounds produced by Aspergillus fungi that can grow on different agricultural crops. Both acute and chronic exposure to these mycotoxins can cause serious illness. Due to the high occurrence of aflatoxins in crops worldwide fast and cost-effective analytical methods are required for the identification of contaminated agricultural commodities before they are processed into final products and placed on the market. In order to provide new tools for aflatoxin screening two prototype fast ELISA methods: one for the detection of aflatoxin B 1 and the other for total aflatoxins were developed. Seven monoclonal antibodies with unique high sensitivity and at the same time good cross-reactivity profiles were produced. The monoclonal antibodies were characterized and two antibodies showing IC 50 of 0.037 ng/mL and 0.031 ng/mL for aflatoxin B 1 were applied in simple and fast direct competitive ELISA tests. The methods were validated for peanut matrix as this crop is one of the most affected by aflatoxin contamination. The detection capabilities of aflatoxin B 1 and total aflatoxins ELISAs were 0.4 μg/kg and 0.3 μg/kg for aflatoxin B 1 , respectively, which are one of the lowest reported values. Total aflatoxins ELISA was also validated for the detection of aflatoxins B 2 , G 1 and G 2 . The application of the developed tests was demonstrated by screening 32 peanut samples collected from the UK retailers. Total aflatoxins ELISA was further applied to analyse naturally contaminated maize porridge and distiller's dried grain with solubles samples and the results were correlated with these obtained by UHPLC-MS/MS method. [ABSTRACT FROM AUTHOR]

Background: Doubled haploid (DH) lines produced via in vivo haploid induction have become indispensable in maize research and practical breeding, so it is important to understand traits characteristics in DH and its corresponding haploids which derived from each DH lines. In this study, a DH population derived from Zheng58 × Chang7-2 and a haploid population, were developed, genotyped and evaluated to investigate genetic architecture of eight stalk traits, especially rind penetrometer resistance (RPR) and in vitro dry matter digestion (IVDMD), which affecting maize stalk lodging-resistance and feeding values, respectively. Results: Phenotypic correlation coefficients ranged from 0.38 to 0.69 between the two populations for eight stalk traits. Heritability values of all stalk traits ranged from 0.49 to 0.81 in the DH population, and 0.58 to 0.89 in the haploid population. Quantitative trait loci (QTL) mapping study showed that a total of 47 QTL for all traits accounting for genetic variations ranging from 1.6 to 36.5 % were detected in two populations. One or more QTL sharing common region for each trait were detected between two different ploidy populations. Potential candidate genes predicated from the four QTL support intervals for RPR and IVDMD were indirectly or directly involved with cellulose and lignin biosynthesis, which participated in cell wall formation. The increased expression levels of lignin and cellulose synthesis key genes in the haploid situation illustrated that dosage compensation may account for genome dosage effect in our study. Conclusions: The current investigation extended understanding about the genetic basis of stalk traits and correlations between DH and its haploid populations, which showed consistence and difference between them in phenotype, QTL characters, and gene expression. The higher heritabilities and partly higher QTL detection power were presented in haploid population than in DH population. All of which described above could lay a preliminary foundation for genetic architecture study with haploid population and may benefit selection in haploid-stage to reduce cost in DH breeding. [ABSTRACT FROM AUTHOR]

Background: The limited genetic diversity of elite maize germplasms raises concerns about the potential to breed for new challenges. Initiatives have been formed over the years to identify and utilize useful diversity from landraces to overcome this issue. The aim of this study was to evaluate the proposed designs to initiate a pre-breeding program within the Seeds of Discovery (SeeD) initiative with emphasis on harnessing polygenic variation from landraces using genomic selection. We evaluated these designs with stochastic simulation to provide decision support about the effect of several design factors on the quality of resulting (pre-bridging) germplasm. The evaluated design factors were: i) the approach to initiate a pre-breeding program from the selected landraces, doubled haploids of the selected landraces, or testcrosses of the elite hybrid and selected landraces, ii) the genetic parameters of landraces and phenotypes, and iii) logistical factors related to the size and management of a pre-breeding program. Results: The results suggest a pre-breeding program should be initiated directly from landraces. Initiating from testcrosses leads to a rapid reconstruction of the elite donor genome during further improvement of the pre-bridging germplasm. The analysis of accuracy of genomic predictions across the various design factors indicate the power of genomic selection for pre-breeding programs with large genetic diversity and constrained resources for data recording. The joint effect of design factors was summarized with decision trees with easy to follow guidelines to optimize pre-breeding efforts of SeeD and similar initiatives. Conclusions: Results of this study provide guidelines for SeeD and similar initiatives on how to initiate pre-breeding programs that aim to harness polygenic variation from landraces. [ABSTRACT FROM AUTHOR]

The European Corn Borer (ECB), Ostrinia nubilalis (Hübner), plays an important role in promoting Fusarium infection and fumonisin production in maize kernels. Moniliformin (MON) is a mycotoxin that is usually found in association with fumonisins (FB), and as a consequence ECB is also expected to play a role in MON contamination. The aim of the current study was to investigate the influence of ECB activity on MON contamination and on the fungi responsible for its contamination. A comparison has been made between maize infected naturally by insect larvae and protected maize, from 2008 to 2010 in North–West Italy; the latter was obtained by positioning an entomological net at the end of maize flowering. The Fusarium proliferatum infection of the maize grain was higher in each growing season than that caused by Fusarium subglutinans , although both species were significantly increased due to the ECB damage to the maize ears. The ECB activity significantly increased the MON content 26-fold in 2008 from 43 to 1137 μg kg −1 , 25-fold in 2009 from < LOQ to 77 μg kg −1 and 94-fold in 2010 from 6 to 564 μg kg −1 . The relationship between the MON content and the Fusarium species producers of MON was closer for F. proliferatum ( r = 0.96, P < 0.001) than for F. subglutinans ( r = 0.83, P < 0.001). An in vitro assay was carried on in order to assess the toxigenic capacity of different F. proliferatum and F. subglutinans strains isolated from a field experiment and artificially inoculated on a maize substrate. On average, the F. proliferatum isolated strains showed a significantly higher ( P < 0.001) toxigenic capacity than the F. subglutinans strains. In conclusion, the combination of the high toxigenic capacity of F. proliferatum , and its more frequent occurrence and greater intensity in the field make it possible to state that the production of MON in maize temperate areas, such as North Italy, is mainly due to F. proliferatum infections and is closely linked to the injury caused by ECB larvae. [ABSTRACT FROM AUTHOR]

An experiment to study combining ability effects through 6×6 diallel model in maize inbred lines, was laid out in randomized complete block design with three replications at Agricultural Research Institute, Dera Ismail Khan, Pakistan, during 2012. Variance analysis exhibited highly significant (P 0.01) variation among genotypes for days to 50% silking, ear length, kernel rows ear-1, kernels row-1, kernels ear-1 and grain yield. Mean square values due to general combining ability were highly significant (P 0.01) for all studied attributes except kernels ear1 and grain yield. Highly significant variations for specific combining ability of direct and reciprocal effects were observed for all attributes. Azam proved good combiner for days to 50% silking and kernel rows ear-1 while Islamabad Gold for kernels ear1 and grain yield. Islamabad White × Sadaf was the best combiner for grain yield. For reciprocal effects, BS-I × Sahiwal 2002 proved good combiner for kernels row1 and kernels ear-1 while BS-I × Islamabad White for grain yield. Selection in early generation will be more effective in Islamabad White whereas Islamabad Gold in later generation due to dominant and additive genetic background, respectively. [ABSTRACT FROM AUTHOR]

Debates about ancient Amazonian social organization have evaluated characterizations from a range of sources that include ethnographically documented foraging societies and archaeological discoveries suggestive of sedentized agriculturists. This study uses qualitative ethnoarchaeological data about foraging and small-scale horticulture among the Pumé of Venezuela, and Lewis Binford’s quantified database of foraging groups and environmental parameters, to develop a testable model that predicts the conditions under which Amazon Basin foragers would (or would not) intensify subsistence to the point of incorporating maize and other cultivars; as well as the conditions for reversing the process. Specific expectations for the archaeological and paleoenvironmental record are proposed as indicators, and assessed relative to what we currently know from the archaeological record. [ABSTRACT FROM AUTHOR]

Ethnographic and environmental data sets developed by Lewis Binford are used to test models about the relationship between forager plant intensification and maize adoption in Central Western Argentina. By examining large suites of cases to identify regular patterns of association, the models describe regular interactions that are apparent in the patterning across known groups. To the extent that people in the past adapted in similar ways to environmental and demographic conditions as people recorded ethnographically, they may be expected to fall within the bounds of general ecological relationships. [ABSTRACT FROM AUTHOR]

DNA methylation is a chromatin modification that is sometimes associated with epigenetic regulation of gene expression. As DNA methylation can be reversible at some loci, it is possible that methylation patterns may change within an organism that is subjected to environmental stress. In order to assess the effects of abiotic stress on DNA methylation patterns in maize (Zea mays), seeding plants were subjected to heat, cold, and UV stress treatments. Tissue was later collected from individual adult plants that had been subjected to stress or control treatments and used to perform DNA methylation profiling to determine whether there were consistent changes in DNA methylation triggered by specific stress treatments. DNA methylation profiling was performed by immunoprecipitation of methylated DNA followed by microarray hybridization to allow for quantitative estimates of DNA methylation abundance throughout the low-copy portion of the maize genome. By comparing the DNA methylation profiles of each individual plant to the average of the control plants it was possible to identify regions of the genome with variable DNA methylation. However, we did not find evidence of consistent DNA methylation changes resulting from the stress treatments used in this study. Instead, the data suggest that there is a low-rate of stochastic variation that is present in both control and stressed plants. [ABSTRACT FROM AUTHOR]

The present study was conducted to present the responses of drought-sensitive 'Shemal' and drought-tolerant '71MAY69' maize cultivars under drought condition (20% Polyethylene glycol, -0.40 MPa) and three different copper concentrations (0.5 mM, 1 mM, 1.5 mM CuSO4⋅5H2O) for 5 days to determine the enzymatic responses of copper treatment in maize leaves. Copper treatments alone did not change stomatal conductance, relative water content, malondialdehyde, proline, hydrogen peroxide content and abscisic acid level according to control groups. Combined treatment (drought and copper) alleviated the damage of PEG-induced drought stress in maize leaves. Superoxide dismutase (SOD), catalase (CAT), glutatione reductase (GR) activity increased and glutathione -S transferase (GST) activity decreased, while ascorbate peroxidase (APX) activity did not change under drought stress in the tolerant cultivar. SOD, CAT and APX were decreased and GST activities were increased while GR did not change in 'Shemal'. Also SOD, APX and CAT activity increased by copper treatment alone in both cultivars. Otherwise combined treatment increased SOD, APX and CAT activity at all concentrations, but GR and GST activity increased only by (PEG+1.5 mM) treatment when compared with PEG treatment alone in sensitive ones. As a result, exogenous copper alleviated drought stress, while it induced an oxidative damage by increasing antioxidant enzyme activities differently from drought tolerance. Copper tolerance in maize is not a common response of its defense mechanism because of different response to copper and drought in the same cultivar. [ABSTRACT FROM AUTHOR]

A half diallel set of eight newly developed white kernel colour quality protein maize inbred lines was utilized to evaluate general combining ability and specific combining ability for yield and its components characters. Combining ability analysis revealed that estimate of specific combining ability (SCA) variances were higher than general combining ability (GCA) variances for all the traits under study, indicating predominance of non-additive gene action of these traits. The parents HUZQPM 3-2, HUZQPM 6-2 and HUZQPM 5 were identified as good combiners for yield and the related traits. The best experimental hybrids, on the basis of specific combining ability (SCA) effects for yield per plant and two to five of its component was HUZQPM 1-1 X HUZQPM 3-2 followed by HUZQPM 1-1 X HUZQPM 5 and HUZQPM 2 X HUZQPM 4-2. Hence, these crosses may be exploited for commercial cultivation in North East Plain Zone (NEPZ) of maize growing area after extensive testing. [ABSTRACT FROM AUTHOR]

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Rapid and reliable estimates of leaf area index (LAI) are important for studies of exchanges of energy and gases in the biosphere-atmosphere continuum. This paper evaluates the field performance of SunScan canopy analysis system for rapid estimation of LAI. Direct and indirect measurements of LAI were made in a maize (Zea mays L.) field at four phenological stages (emergence, vegetative, flowering and physiological maturity) at a tropical site in Ghana during the Glowa Vota Project field campaign (www.glowa-volta.de). Similar measurements were repeated in early and late planting seasons with similar crop management practices. The result showed a generally good performance of this sensor at all the phenological stages. Average LAI from the sensor (LAIS), ranged from 0.40-4.45, and was consistently higher than the actual LAI, which varied from 0.31-4.22, respectively for both seasons. Regression between LAI and LAIS showed a range of significant correlations with R² > 0.74 for all the stages and seasons. With combined datasets for all stages and the two plantings, a simple regression model was fitted to estimate LAI from LAIS with R² = 0.97 and standard error of 0.23 (P < 0.0001). The evaluated sensor yielded a good and reliable LAI estimates under maize canopy. [ABSTRACT FROM AUTHOR]

Abstract: Objective: To elucidate the pattern of inheritance and determine the relative magnitude of various genetic effects for maturity and flowering attributes in subtropical maize. Methods: Four white grain maize inbred lines from flint group of corn, two with late maturity and two with early maturity, were used. These contrasting inbred lines were crossed to form four crosses. Six generations (P1, P2, F1, F2, BC1, and BC2) were developed for each individual cross. These were evaluated in triplicate trial for two consecutive years. Results: Both dominance gene action and epistatic interaction played major role in governing inheritance of days to pollen shedding, 50% silking, anthesis silking interval and maturity. Conclusions: Preponderance of dominance gene action for these traits indicated their usefulness in hybrid programs of subtropical maize. [Copyright &y& Elsevier]

Abstract: To support the key role of glutathione (GSH) in the mechanisms of tolerance and accumulation of arsenic in plants, this work examines the impact of several effectors of GSH synthesis or action in the response of maize (Zea mays L.) to arsenic. Maize was exposed in hydroponics to iso-toxic rates of 150μM arsenate or 75μM arsenite for 9days and GSH effectors, flurazole (an herbicide safener), l-buthionine-sulfoximine (BSO, a known inhibitor of GSH biosynthesis), and dimercaptosuccinate (DMS) and dimercaptopropanesulfonate (DMPS) (two thiols able to displace GSH from arsenite-GSH complexes) were assayed. The main responses of plants to arsenic exposure consisted of a biomass reduction (fresh weight basis) of about 50%, an increase of non-protein thiol (NPTs) levels (especially in the GSH precursor γ-glutamylcysteine and the phytochelatins PC2 and PC3) in roots, with little effect in shoots, and an accumulation of between 600 and 1000ppm of As (dry weight basis) in roots with very little translocation to shoots. Growth inhibition caused by arsenic was partially or completely reversed in plants co-treated with flurazole and arsenate or arsenite, respectively, highly exacerbated in plants co-treated with BSO, and not modified in plants co-treated with DMS or DMPS. These responses correlated well with an increase of both NPTs levels in roots and glutathione transferase activity in roots and shoots due to flurazole treatment, the decrease of NPTs levels in roots caused by BSO and the lack of effect on NPT levels caused by both DMS and DMPS. Regarding to arsenic accumulation in roots, it was not modified by flurazole, highly reduced by BSO, and increased between 2.5- and 4.0-fold by DMS and DMPS. Therefore, tolerance and accumulation of arsenic by maize could be manipulated pharmacologically by chemical effectors of GSH. [Copyright &y& Elsevier]

BACKGROUND: Aflatoxin, a potent fungal toxin, contaminates 25% of crops worldwide. Since 2004, 477 aflatoxin poisonings associated with eating contaminated maize have been documented in Eastern Kenya, with a case-fatality rate of 40%. OBJECTIVE: We characterized maize aflatoxin contamination during the high-risk season (April--June) after the major harvests in 2005, 2006 (aflatoxicosis outbreak years), and 2007 (a non-outbreak year). Methods: Households were randomly selected each year from the region in Kenya where outbreaks have consistently occurred. At each household, we obtained at least one maize sample (n = 716) for aflatoxin analysis using immunoaffinity methods and administered a questionnaire to determine the source (i.e., homegrown, purchased, or relief) and amount of maize in the household. RESULTS: During the years of outbreaks in 2005 and 2006, 41% and 51% of maize samples, respectively, had aflatoxin levels above the Kenyan regulatory limit of 20 ppb in grains that were for human consumption. In 2007 (non-outbreak year), 16% of samples were above the 20-ppb limit. In addition, geometric mean (GM) aflatoxin levels were significantly higher in 2005 (GM = 12.92, maximum = 48,000 ppb) and 2006 (GM = 26.03, maximum = 24,400 ppb) compared with 2007 (GM = 1.95, maximum = 2,500 ppb) (p-value < 0.001). In all 3 years combined, maize aflatoxin levels were significantly higher in homegrown maize (GM = 17.96) when compared with purchased maize (GM = 3.64) or relief maize (GM = 0.73) (p-value < 0.0001). CONCLUSIONS: Aflatoxin contamination is extreme within this region, and homegrown maize is the primary source of contamination. Prevention measures should focus on reducing homegrown maize contamination at the household level to avert future outbreaks. [ABSTRACT FROM AUTHOR]

Genetic variability and correlations were studied in 40 inbred lines of maize. The data were recorded on seed yield and it’s related traits. Grain yield was found to be significantly and positively correlated with plant height, ear height, ear girth, number of seed rows per ear, number of seeds per row, number of seeds per ear and 100-seed weight. Number of seeds per ear exhibited highest positive correlation with grain yield followed by plant height, number of seeds per row, ear height, 100 seed weight, ear girth, and number of seed rows per ear. The character days to 50% tasselling and days to 50% silking exhibited significant negative genotypic correlation with grain yield. Number of seeds per cob and grain yield estimates combined with high genotypic coefficient of variation with high heritability indicating additive gene action controlling these traits. [ABSTRACT FROM AUTHOR]

Abstract: The present work developed an analytical method for simultaneous determination of fumonisins B1, B2 and B3 residues in maize by ultra high-performance liquid chromatography combined with electrospray ionization triple quadrupole tandem mass spectrometry (UHPLC–MS/MS) under the multiple reaction monitoring (MRM) mode, and especially focused on the optimization of extraction, clean-up, UHPLC separation and MS/MS parameters. The method involves addition of fumonisins isotope internal standards, extraction with a mixture of acetonitrile and water and clean-up with solid-phase extraction (SPE) cartridges before UHPLC–MS/MS analysis. A single-laboratory method validation was conducted by testing three different spiking levels for repeatability and recovery according to International Union of Pure and Applied Chemistry (IUPAC) guidelines. The LOQ of FB1, FB2 and FB3 were 1.50, 1.65 and 0.4μgkg−1, respectively, which were lower than the criteria of EU, USA and other countries regarding minimum residue limits of fumonisins in foods including baby foods and feedstuffs. Recoveries of three fumonisins ranged from 80.9% to 97.0% with RSD values of 2.4–11.1%.The advantages of this method include simple pretreatment, rapid determination and high sensitivity, and it fulfills the requirements for food analysis with respect to minimum residue limits of fumonisins in various countries. [Copyright &y& Elsevier]

Plant species differ in nutrient uptake efficiency. With a pot experiment, we evaluated potassium (K) uptake efficiency of maize ( Zea mays L.), wheat ( Triticum aestivum L.), and sugar beet ( Beta vulgaris L.) grown on a low-K soil. Sugar beet and wheat maintained higher shoot K concentrations, indicating higher K uptake efficiency. Wheat acquired more K because of a greater root length to shoot dry weight ratio. Sugar beet accumulated more shoot K as a result of a 3- to 4-fold higher K influx as compared to wheat and maize, respectively. Nutrient uptake model NST 3.0 closely predicted K influx when 250 mg K kg−1 were added to the soil, but under-predicted K influx under low K supply. Sensitivity analysis showed that increasing soil solution K concentration (CLi) by a factor of 1.6–3.5 or buffer power (b) 10- to 50-fold resulted in 100% prediction of K influx. When both maximum influx (Imax) and b were increased by a factor of 2.5 in maize and wheat and 25 in sugar beet, the model could predict measured K influx 100%. In general, the parameter changes affected mostly calculated K influx of root hairs, demonstrating their possible important role in plant K efficiency. [ABSTRACT FROM AUTHOR]

Abstract: An anti-DON monoclonal antibody (Mab) was produced from a stable hybridoma cell line, 12D1, generated by the fusion of SP2/O myeloma cells with spleen cells isolated from a Balb/c mouse immunized with DON–cationic bovine serum albumin (CBSA) conjugate. The 12D1 Mab belongs to the immunoglobulin G1 (κ-chain) isotype. A colloidal gold immunochromatographic strip (ICS) test for rapid detection of deoxynivalenol (DON) in wheat and maize samples was also developed using this Mab. The ICS test, which has a detection limit of 50ngmL−1 for DON and can be completed in 10min. Analysis of DON in wheat and maize samples revealed that data obtained from ICS test were in a good agreement with those obtained from ELISA and GC/MS. The results demonstrate that the ICS test can be used as qualitative tool for screening technique of DON on-site. [Copyright &y& Elsevier]

The aim of this study was to evaluate the potential for use of an electronic nose for rapid identification of maize samples contaminated with aflatoxins. Principal component analysis (PCA) and linear discriminant analysis (LDA) were used to investigate whether the electronic nose was able to distinguish between contaminated and non-contaminated maize samples. The obtained results indicate that the electronic nose was able to distinguish between maize samples according to the presence and absence of total aflatoxins. LDA was 100% correct in making prediction. These results could be used in further studies aimed at development of a robust classification model, which could be useful to screen for aflatoxins at concentration limits proposed by the European legislation. [ABSTRACT FROM AUTHOR]

The aim was to evaluate the distribution of aflatoxins and fumonisins in fractions derived from the dry-milling of contaminated maize. Two maize lots with different contamination levels were processed and sampled: the first (maize 1) had aflatoxin B1 (AFB1) and fumonisin B1 (FB1) levels of 3.6 and 5379 µg kg-1, respectively; the second (maize 2) had corresponding levels of 91.1 and 8841 µg kg-1, respectively. The cleaning step reduced AFB1 and FB1 levels by 8 and 11% in maize 1 and by 57 and 34% in maize 2. The subsequent removal of bran and germ led to a further decrease in contamination levels in the products destined for human consumption. In the latter, AFB1 was uniformly distributed, while FB1 was concentrated in the finer size fractions. Contamination of raw maize 1 (3.6 µg kg-1) was below the European Union AFB1 limit of 5 µg kg-1 for unprocessed maize, but among the final products only coarse flour (1.7 µg kg-1) was within the European Union limit of 2 µg kg-1, while grits and fine flour showed higher levels (2.7 and 2.5 µg kg-1, respectively). As regards cleaned maize, a different distribution of the two toxins was observed in the kernels: AFB1 contamination was more superficial and concentrated in germ, while FB1 contamination affected the inner layers of the kernels. [ABSTRACT FROM AUTHOR]

This study examined a total of 82 consignments of French and Argentinean raw maize as received at maize mills in the UK between 2004 and 2007. Samples were analysed for deoxynivalenol (DON), nivalenol (NIV), other trichothecenes, zearalenone (ZON), and fumonisins B1, B2, and B3 (FB1, FB2, and FB3) using fully validated analytical methods with limits of quantification of 10 µg kg-1 for DON, NIV, and each fumonisin mycotoxin and 3 µg kg-1 for ZON. All samples except two containing fumonisins met the European Commission statutory maximum permissible levels for DON, ZON, and FB1 + FB2 as operating in 2007. The maximum concentrations found for DON, NIV, ZON, and FB1 + FB2 were 444, 496, 165 and 5002 µg kg-1, respectively. Fumonisins were detected in almost every sample with 65% of Argentinean maize containing more than 1000 µg kg-1 of FB1 + FB2. In contrast, ZON was not detectable in almost 50% of consignments. During this period there was a distinct difference in mycotoxin concentrations between harvests and geographic origin. Flint maize from Argentina usually contained lower concentrations of DON and related trichothecenes and higher levels of fumonisins than maize from France, although concentrations of fumonisins up to 2000 µg kg-1 or greater occurred in samples from both regions. The incidence and concentrations of fumonisins were similar to those in a similar previous survey, while zearalenone concentrations were lower. The distribution of mycotoxins in multi-hold ships was also investigated showing that fumonisins were much more evenly distributed than DON, thus indicating their general level in the ship as a whole. The effect of cleaning regimes was found to be very variable, especially for DON, ranging from no removal of mycotoxins to greater than 50% in some instances, but was not related to concentration. Evidence here suggests that while cleaning is essential for removing foreign bodies before milling, it cannot be used as a reliable tool for reducing mycotoxins. [ABSTRACT FROM AUTHOR]

Up-to-date fertilizer recommendation systems are based not only on soil analysis but also on diagnostic plant analysis. Plant analysis provides information on many aspects of plant nutrition. This work aimed at providing data about the effect of nitrogen (N) supplies on the grain yield and nutrient concentrations in maize leaves at the beginning of tasselling as well as on interactions between nutrients, based on the result of long-term fertilization experiments carried out on Chernozem meadow soil. The experiments were set up with a total combination of 64 fertilizer treatments [4 N × 4 phosphorus (P) × 4 potassium (K)]. An increase in the nitrate (NO3) N reserves in the soil prior to sowing, according to the N application rate (0, 80, 160, 240 kg ha-1), resulted in higher grain yield and caused a rise in the leaf N and manganese (Mn) contents, and occasionally in the P and zinc (Zn) concentrations. The calcium (Ca), magnesium (Mg), and copper (Cu) concentrations of the leaf were influenced by the N supply in only 1 year, when the water supply was the best and the grain yield was the highest. At the beginning of tasselling, the satisfactory N concentration limit value at 95% of maximum of maize grain yield was 2.2-4.0%. Satisfactory N concentration was observed if the NO3-N content of the 0- to 60-cm soil layer prior to sowing reached 80-100 kg ha-1. Interactions were observed between the N concentration and the Mn, P, Zn, Ca, Mg, and Cu contents of the leaf. The changes caused by N supply in these element concentrations remained within the limits of satisfactory supplies. [ABSTRACT FROM AUTHOR]

Maize seedling transcriptome responses to six abiotic perturbations (heat, cold, darkness, desiccation, salt, ultraviolet-B) were analysed. Approximately 7800 transcripts were expressed in one or more treatments compared with light-grown seedlings plus juvenile leaves from field-grown plants. Approximately 5200 transcripts were expressed in one or more treatments and absent in light-grown seedlings. Approximately 2000 transcripts were unique to one treatment. Salt and heat elicited the largest number of transcript changes; however, salt resulted in mostly a decreased abundance of transcripts, whereas heat shock resulted in mostly an increased abundance of transcripts. A total of 384 transcripts were common to all stress treatments and not expressed in light-grown seedlings; 146 transcripts were present in light-grown seedlings and absent from all stress treatments. A complex pattern of overlapping transcripts between treatments was found, and a significant pattern of congruence in the direction of transcript change between pairs of treatments was uncovered. From the analysis, it appears that the scope of gene expression changes is determined by the challenge, indicating specificity in perception and response. Nonetheless, transcripts regulated by multiple responses are generally affected in the same manner, indicating common or converging regulatory networks. The data are available for additional analysis through a searchable database. [ABSTRACT FROM AUTHOR]

The work analyses the obtained good and the way of turning to account of the irrigation water delivered in 2 ways of irrigation (700 m3/ha and 1800 m3/ha) for 18 hybrids of maize with middle time of vegetation FAO 400- 500. The way of turning to account the irrigation water it was made by comparing good obtained by the 2 ways of irrigation and by the increasing of production made for 100 m3/ha of water, in both of the ease. [ABSTRACT FROM AUTHOR]

When evaluating genotypes, it is efficient and resourceful to identify similar testing sites and group them according to similarity. Grouping sites ensures that breeders choose as many variable sites as possible to capture the effects of genotype-by-environment (GE) interactions. In order to exploit these interactions and increase testing efficiency and variety selection, it is necessary to group similar environments or mega-environments. The present mega-environments in the Southern African Development Community (SADC) countries are confounded within each country, which limits the exchange of germplasm among them. The objective of this study was to revise and group similar maize-testing sites across the SADC countries that are not confounded within each country. The study was based on 3 years (1999–2001) of regional maize yield trial data and geographical information systems (GIS) parameters from 94 sites. Sequential retrospective (Seqret) pattern analysis methodology was used to stratify testing sites and group them according to their similarity and dissimilarity based on mean grain yield. The methodology used historical data, taking into account imbalances of data caused by changes over locations and years, such as additions and omission of genotypes and locations. Cluster analysis grouped regional trial sites into seven mega-environments, mainly distinguished by GIS parameters related to rainfall, temperature, soil pH, and soil nitrogen with an overall R2 = 0.70. This analysis provides a challenge and an opportunity to develop and deploy maize germplasm in the SADC region faster and more effectively. [ABSTRACT FROM AUTHOR]

Corn is a staple food of Anhui Province. For example, the growing area of corn keeps increasing in Suixi County recently. In 2014, Hua'an No.513 was introduced to Chenlou Village, Suntuan Town, totaling 2.67 hm2, and yield reached as high as 9 558 kg/hm2. The research explored simplified cultivation technology in demonstration regions in Suixi County of Hua'an No.513 in order to investigate the highly-yielding and highly-efficient cultivation technology of Hua'an No.513 and provide supports for farmers to increase yield and incomes and guarantee crop safety. [ABSTRACT FROM AUTHOR]