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Summary All aerial epidermal cells in land plants are covered by the cuticle, an extracellular hydrophobic layer that provides protection against abiotic and biotic stresses and prevents organ fusion during development.Genetic and morphological analysis of the classic maize adherent1 (ad1) mutant was combined with genome‐wide binding analysis of the maize MYB transcription factor FUSED LEAVES1 (FDL1), coupled with transcriptional profiling of fdl1 mutants.We show that AD1 encodes an epidermally‐expressed 3‐KETOACYL‐CoA SYNTHASE (KCS) belonging to a functionally uncharacterized clade of KCS enzymes involved in cuticular wax biosynthesis. Wax analysis in ad1 mutants indicates that AD1 functions in the formation of very‐long‐chain wax components. We demonstrate that FDL1 directly binds to CCAACC core motifs present in AD1 regulatory regions to activate its expression. Over 2000 additional target genes of FDL1, including many involved in cuticle formation, drought response and cell wall organization, were also identified.Our results identify a regulatory module of cuticle biosynthesis in maize that is conserved across monocots and eudicots, and highlight previously undescribed factors in lipid metabolism, transport and signaling that coordinate organ development and cuticle formation.

Comparisons among C4 maize, sorghum, and pearl millet show that soil type and source–sink balance affect transpiration efficiency under high vapor pressure deficit in a species-dependent manner., We have previously reported that there is a tight link between high transpiration efficiency (TE; shoot biomass per unit water transpired) and restriction of transpiration under high vapor pressure deficit (VPD). In this study, we examine other factors affecting TE among major C4 cereals, namely species’ differences, soil type, and source–sink relationships. We found that TE in maize (10 genotypes) was higher overall than in pearl millet (10 genotypes), and somewhat higher than in sorghum (16 genotypes). Overall, transpiration efficiency was higher in high-clay than in sandy soil under high VPD, but the effect was species-dependent with maize showing large variations in TE and yield across different soil types whilst pearl millet showed no variation in TE. This suggested that species fitness was specific to soil type. Removal of cobs drastically decreased TE in maize under high VPD, but removal of panicles did not have the same effect in pearl millet, suggesting that source–sink balance also drove variations in TE. We interpret the differences in TE between species as being accounted for by differences in the capacity to restrict transpiration under high VPD, with breeding history possibly having favored the source–sink balance in maize. This suggests that there is also scope to increase TE in pearl millet and sorghum through breeding. With regards to soil conditions, our results indicate that it appears to be critical to consider hydraulic characteristics and the root system together in order to better understand stomatal regulation and restriction of transpiration under high VPD. Finally, our results highlight the importance of sink strength in regulating transpiration/photosynthesis, and hence in influencing TE.

Because plants capture water and nutrients through roots, it was proposed that changes in root systems architecture (RSA) might underpin the 3-fold increase in maize (Zea mays L.) grain yield over the last century. Here we show that both RSA and yield have changed with decades of maize breeding, but not the crop water uptake. Results from X-ray phenotyping in controlled environments showed that single cross (SX) hybrids have smaller root systems than double cross (DX) hybrids for root diameters between 2465 µm and 181µm (P, Emerging opportunity to continue long-term genetic gain in maize yield in the US corn belt by improving the balance between canopy, root, and reproductive growth and development.

The study reported here was to determine the effect of an application of organic and mineral materials and their mixtures, combined with mineral fertiliser regime, on the content of selected macroelements in cocksfoot grass and maize. The trial was a completely randomised arrangement with three replicates. Two experimental factors were tested: factor A – fertilisation with organic and mineral materials ( sewage sludge fresh and composted, hard coal incineration ashes , calcium carbonate, mixture of this components) and factor B – mineral fertilisation. The observed effects are indicative of the legitimacy of applying sewage sludge and its mixture with hard coal ash to fertilise agricultural crops as this would reduce reliance on mineral fertiliser, which is very desirable in sustainable agriculture. Mineral fertilisation applied to both the test plants significantly reduced their contents of calcium and magnesium but it increased their content of potassium.

Heterosis has been extensively utilized to increase productivity in crops, yet the underlying molecular mechanisms remain largely elusive. Here, we generated transcriptome-wide profiles of mRNA abundance, m6A methylation, and translational efficiency from the maize F1 hybrid B73×Mo17 and its two parental lines to ascertain the contribution of each regulatory layer to heterosis at the seedling stage. We documented that although the global abundance and distribution of m6A remained unchanged, a greater number of genes had gained an m6A modification in the hybrid. Superior variations were observed at the m6A modification and translational efficiency levels when compared with mRNA abundance between the hybrid and parents. In the hybrid, the vast majority of genes with m6A modification exhibited a non-additive expression pattern, the percentage of which was much higher than that at levels of mRNA abundance and translational efficiency. Non-additive genes involved in different biological processes were hierarchically coordinated by discrete combinations of three regulatory layers. These findings suggest that transcriptional and post-transcriptional regulation of gene expression make distinct contributions to heterosis in hybrid maize. Overall, this integrated multi-omics analysis provides a valuable portfolio for interpreting transcriptional and post-transcriptional regulation of gene expression in hybrid maize, and paves the way for exploring molecular mechanisms underlying hybrid vigor., A maize F1 hybrid and its parental lines showed dissimilarities of regulatory and heterotic patterns of genes undergoing hierarchical regulation at the mRNA abundance, m6A modification, and translational efficiency.

Background. Innovative technologies for deep processing of grain are widely used in maize grain processing with the release of the grain germ for subsequent extraction of oil and starch from it or production of sugar substitutes in the form of fructose syrup and alcohol, bakery or feed protein. A search for economically valuable sources of maize starch, useful byproducts of its processing, and natural modification of starch for deep processing is vital.Materials and methods. Ten high-starch maize accessions from the VIR collection, isolated by IR spectrometry, were studied. Starch content was measured according to GOST 10845-98, GOST 13586.5-93, GOST 10847-74 and GOST ISO 6647-1-2015 standards. Processing of grain into starch and assessment of the content of amylose and byproducts were carried out at the All-Russian Scientific Research Institute for Starch Products in 2018 according to L. P. Nosovskaya et al. The actual content of starch and its byproducts during deep grain processing was determined. The values of the actual percentage of dry matter (DM, %) in grain, mass fraction of starch, ash content, as well as the yield of extract, pulp, embryo, gluten, process water and starch were determined.Results. Accessions with a high yield of starch (k-4520, k-9301 and k-24730), germ (k-4520. k-8785 and k-24731), pulp (k-4520, k-8785, k-9991 and k-24732) and protein (k8785) were identified as well as those with a percentage of amylopectin in starch above 82% (k-24730 and k-24733) and 100% (k-5461 and k-9991), and amylose above 30% (k4520 and k-9301).Conclusion. Of practical interest in terms of the actual yield of starch (% DM in grain) are accessions k-4520, k-9301, k-24730, k-9991, k-5461 and k-4520. According to the results of breeding tests, accessions k-24730, k-24732 and k-24733 had the following values of starch harvest calculated for grain yield: 4.66, 4.41 and 4.18 t/ha, respectively.

In most of the countries around the world, the ever increase in food processing industries around the world is producing various types of by-products including peel, bran, pomace, refused pulp, shells, hull, husk, pods, seeds. With increasing activity in health-promoting functional foods, increase in the demand for natural bioactive moieties and new areas of research are on the way. Many by-products have been explored for health endorsing properties however, maize bran cell walls (MBCWs) and their various components (non-starch polysaccharides) are of chief importance. In this review, efforts are focused to illustrate the functional and nutraceutical importance of maize bran cell walls. Maize bran cell wall is made up of non-starch polysaccharide materials including arabinoxylans, heteroxylans, and hemicellulose. It holds various bioactive compounds such as ferulic acid, diferulic acid, and p-coumaric acid, having enormous nutraceutical properties, like antioxidant, anticancer, anti-inflammatory, anti-microbial, antiaging, cardioprotective, prebiotic and antiviral effects. These bioactive compounds are protecting against various disorders, like hypercholesterolemia, diabetes, cancer, neurodegenerative, cardiovascular, and thrombosis diseases. Furthermore, extraction, functional and nutraceutical properties, possible uses, and industrial applications of MBCW are the limelight of this article.

Maize is the most important staple crop worldwide. Many of its agronomic traits present with a high level of heterosis. Combining ability was proposed to exploit the rule of heterosis, and general combining ability (GCA) is a crucial measure of parental performance. In this study, a recombinant inbred line population was used to construct testcross populations by crossing with four testers based on North Carolina design II. Six yield-relevant traits were investigated as phenotypic data. GCA effects were estimated for three scenarios based on the heterotic group and the number of tester lines. These estimates were then used to identify quantitative trait loci (QTL) and dissect genetic basis of GCA. A higher heritability of GCA was obtained for each trait. Thus, testing in early generation of breeding may effectively select candidate lines with relatively superior GCA performance. The GCA QTL detected in each scenario was slightly different according to the linkage mapping. Most of the GCA-relevant loci were simultaneously detected in all three datasets. Therefore, the genetic basis of GCA was nearly constant although discrepant inbred lines were appointed as testers. In addition, favorable alleles corresponding to GCA could be pyramided via marker-assisted selection and made available for maize hybrid breeding.

Aims We sought to develop a novel experimental system which enabled application of iodinated contrast media to in vivo plant roots intact in soil and was compatible with time-resolved synchrotron X-ray computed tomography imaging. The system was developed to overcome issues of low contrast to noise within X-ray computed tomography images of plant roots and soil environments, the latter of which can complicate image processing and result in the loss of anatomical information. Methods To demonstrate the efficacy of the system we employ the novel use of both synchrotron X-ray computed tomography and synchrotron X-ray fluorescence mapping to capture the translocation of the contrast media through root vasculature into the leaves. Results With the application of contrast media we identify fluid flow in root vasculature and visualise anatomical features, which are otherwise often only observable in ex vivo microscopy, including: the xylem, metaxylem, pith, fibres in aerenchyma and leaf venation. We are also able to observe interactions between aerenchyma cross sectional area and solute transport in the root vasculature with depth. Conclusions Our novel system was capable of successfully delivering sufficient contrast media into root and leaf tissues such that anatomical features could be visualised and internal fluid transport observed. We propose that our system could be used in future to study internal plant transport mechanisms and parameterise models for fluid flow in plants.

Late wilt disease, caused by Cephalosporium maydis in maize plant, is one of the main economical diseases in Egypt. Therefore, to cope with this problem, we investigated the potentiality of plant growth promoting rhizobacteria in controlling this disease. Six strains (Bacillus subtilis, B. circulance, B. coagulanse, B. licheniformis, Pseudomonas fluroscence and P. koreensis) were screened for siderophore production, and using dual plate culture method and greenhouse experiment, antagonistic activity against C. maydis was studied. Using two superior strains, single and dual inoculation treatments in maize were applied in field experiment during the 2018 and 2019 seasons. Results indicated that B. subtilis and P. koreensis strains had shown the most qualitative and quantitative assays for siderophore production and antagonistic activities. In greenhouse, the most effective treatments on the pre- and post-emergence damping off as well as growth promotion of maize were T3 treatment (inoculated with B. subtilis), and T8 treatment (inoculated with P. koreensis). In field experiment, T5 treatment (inoculated with a mixture of B. subtilis and P. koreensis) showed significant increases in catalase (CAT), peroxidase (POX) and polyphenol oxidase (PPO) activities, as well as total chlorophyll and carotenoids than control treatments during the two growing seasons. In the same way, the highest effect in reducing infection and increasing the thickness of the sclerenchymatous sheath layer surrounding the vascular bundles in maize stem was observed and these results were a reflection of the increase in yield and yield parameters. Electronic Supplementary Material The online version of this article (10.1007/s00203-020-02113-5) contains supplementary material, which is available to authorized users.

One of the major sources of uncertainty in large-scale crop modeling is the lack of information capturing the spatiotemporal variability of crop sowing dates. Remote sensing can contribute to reducing such uncertainties by providing essential spatial and temporal information to crop models and improving the accuracy of yield predictions. However, little is known about the impacts of the differences in crop sowing dates estimated by using remote sensing (RS) and other established methods, the uncertainties introduced by the thresholds used in these methods, and the sensitivity of simulated crop yields to these uncertainties in crop sowing dates. In the present study, we performed a systematic sensitivity analysis using various scenarios. The LINTUL-5 crop model implemented in the SIMPLACE modeling platform was applied during the period 2001–2016 to simulate maize yields across four provinces in South Africa using previously defined scenarios of sowing dates. As expected, the selected methodology and the selected threshold considerably influenced the estimated sowing dates (up to 51 days) and resulted in differences in the long-term mean maize yield reaching up to 1.7 t ha−1 (48% of the mean yield) at the province level. Using RS-derived sowing date estimations resulted in a better representation of the yield variability in space and time since the use of RS information not only relies on precipitation but also captures the impacts of socioeconomic factors on the sowing decision, particularly for smallholder farmers. The model was not able to reproduce the observed yield anomalies in Free State (Pearson correlation coefficient: 0.16 to 0.23) and Mpumalanga (Pearson correlation coefficient: 0.11 to 0.18) in South Africa when using fixed and precipitation rule-based sowing date estimations. Further research with high-resolution climate and soil data and ground-based observations is required to better understand the sources of the uncertainties in RS information and to test whether the results presented herein can be generalized among crop models with different levels of complexity and across distinct field crops.

In sweetcorn, as kernel number increased, kernel Zn concentration decreased. However, total kernel Zn per cob increased, as the small decreases in kernel Zn concentration were offset by increases in kernel number., Grain yield and mineral nutrient concentration in cereal crops are usually inversely correlated, undermining biofortification efforts. Here, sink size, expressed as kernel number per cob, was manipulated by controlling the time when the silks of sweetcorn (Zea mays) cv. Hybrix 5 and var. HiZeax 103146 were exposed to pollen. Twelve other varieties were manually pollinated to achieve the maximum potential kernel number per cob, and kernel Zn concentration was correlated with kernel number and kernel mass. As kernel number increased, kernel Zn concentration decreased, with the decrease occurring to similar extents in the embryo tissue and the rest of the kernel. However, total kernel Zn accumulated per cob increased with increasing kernel number, as the small decreases in individual kernel Zn concentration were more than offset by increases in kernel number. When both kernel number and mass were considered, 90% of the variation in kernel Zn concentration was accounted for. Differential distribution of assimilates and Zn to sweetcorn cobs led to significant decreases in kernel Zn concentration with increasing kernel number. This suggests there will be challenges to achieving high kernel Zn concentrations in modern high-yielding sweetcorn varieties unless genotypes with higher Zn translocation rates into kernels can be identified.

A MADS-box transcription factor transcriptionally up-regulated and modulating lateral root development in response to local nitrate supply exists as a truncated form unique to grass species., Plants can develop root systems with distinct anatomical features and morphological plasticity to forage nutrients distributed heterogeneously in soils. Lateral root proliferation is a typical nutrient-foraging response to a local supply of nitrate, which has been investigated across many plant species. However, the underlying mechanism in maize roots remains largely unknown. Here, we report on identification of a maize truncated MIKC-type MADS-box transcription factor (ZmTMM1) lacking K- and C-domains, expressed preferentially in the lateral root branching zone and induced by the localized supply of nitrate. ZmTMM1 belongs to the AGL17-like MADS-box transcription factor family that contains orthologs of ANR1, a key regulator for root nitrate foraging in Arabidopsis. Ectopic overexpression of ZmTMM1 recovers the defective growth of lateral roots in the Arabidopsis anr1 agl21 double mutant. The local activation of glucocorticoid receptor fusion proteins for ZmTMM1 and an artificially truncated form of AtANR1 without the K- and C-domains stimulates the lateral root growth of the Arabidopsis anr1 agl21 mutant, providing evidence that ZmTMM1 encodes a functional MADS-box that modulates lateral root development. However, no phenotype was observed in ZmTMM1-RNAi transgenic maize lines, suggesting a possible genetic redundancy of ZmTMM1 with other AGL17-like genes in maize. A comparative genome analysis further suggests that a nitrate-inducible transcriptional regulation is probably conserved in both truncated and non-truncated forms of ZmTMM1-like MADS-box transcription factors found in grass species.

Objectives To develop a sensitive monoclonal antibody-based sandwich enzyme-linked immunosorbent assay (ELISA) to detect Vip3Aa in genetically modified (GM) crops and their products. Results Vegetative insecticidal proteins (Vips) are secreted by Bacillus thuringiensis (Bt) and are known to be toxic to Lepidoptera species. Vip3Aa family proteins, Vip3Aa19 and Vip3Aa20, were successfully applied in GM crops to confer an effective and persistent insecticidal resistance. A sensitive monoclonal antibody-based sandwich ELISA was developed to detect Vip3Aa in GM crops and their products. Two monoclonal antibodies were raised against the overexpressed and purified His-Vip3Aa20, were purified from mouse ascites and characterized. A sandwich ELISA method was developed using the 2G3-1D7 monoclonal antibody for capture and the biotin-labeled 1F9-1F5 monoclonal antibody for detection of Vip3Aa20. The linear detection range of the method was found to be approximately 31.25–500 pg/ml, with a sensitivity of 10.24 pg/ml. Conclusions The established ELISA was effective for detecting Vip3Aa family proteins other than Vip3Aa8, and was successfully applied in the detection of Vip3Aa20 and Vip3Aa19 expressed in transgenic maize and cotton.

This study assesses the economic and environmental impacts that have arisen from the adoption and use of genetically modified (GM) cotton and maize in Colombia in the fifteen years since GM cotton was first planted in Colombia in 2003. A total of 1.07 million hectares have been planted to cotton and maize containing GM traits since 2003, with farmers benefiting from an increase in income of US $301.7 million. For every extra US $1 spent on this seed relative to conventional seed, farmers have gained an additional US $3.09 in extra income from growing GM cotton and an extra US $5.25 in extra income from growing GM maize. These income gains have mostly arisen from higher yields (+30.2% from using stacked (herbicide tolerant and insect resistant cotton and +17.4% from using stacked maize). The cotton and maize seed technology have reduced insecticide and herbicide spraying by 779,400 kg of active ingredient (−19%) and, as a result, decreased the environmental impact associated with herbicide and insecticide use on these crops (as measured by the indicator, the Environmental Impact Quotient (EIQ)) by 26%. The technology has also facilitated cuts in fuel use, resulting in a reduction in the release of greenhouse gas emissions from the GM cotton and maize cropping area and contributed to saving scarce land resources.

We highlight different approaches used to induce boron deficiency in plants and how this has led to differences in interpretation of boron’s role in the cell wall versus the cytosol., Deficiency of the essential nutrient boron (B) in the soil is one of the most widespread micronutrient deficiencies worldwide, leading to developmental defects in root and shoot tissues of plants, and severe yield reductions in many crops. Despite this agricultural importance, the underlying mechanisms of how B shapes plant developmental and morphological processes are still not unequivocally understood in detail. This review evaluates experimental approaches that address our current understanding of how B influences plant morphological processes by focusing on developmental defects observed under B deficiency. We assess what is known about mechanisms that control B homeostasis and specifically highlight: (i) limitations in the methodology that is used to induce B deficiency; (ii) differences between mutant phenotypes and normal plants grown under B deficiency; and (iii) recent research on analyzing interactions between B and phytohormones. Our analysis highlights the need for standardized methodology to evaluate the roles of B in the cell wall versus other parts of the cell.

Leaf angle (LA) is a critical agronomic trait in maize, with more upright leaves allowing higher planting density, leading to more efficient light capture and higher yields. A few genes responsible for variation in LA have been identified by map-based cloning. In this study, we cloned maize ZmIBH1-1, which encodes a bHLH transcription factor with both a basic binding region and a helix-loop-helix domain, and the results of qRT-PCR showed that it is a negative regulator of LA. Histological analysis indicated that changes in LA were mainly caused by differential cell wall lignification and cell elongation in the ligular region. To determine the regulatory framework of ZmIBH1-1, we conducted RNA-seq and DNA affinity purification (DAP)-seq analyses. The combined results revealed 59 ZmIBH1-1-modulated target genes with annotations, and they were mainly related to the cell wall, cell development, and hormones. Based on the data, we propose a regulatory model for the control of plant architecture by ZmIBH1-1 in maize., ZmIBH1-1 encodes a bHLH transcription factor that affects the leaf angle in maize primarily through differential cell wall lignification and cell elongation in the ligular region.

Background and Aim: Water crisis in many regions of the world especially arid and semi-arid areas such as Iran, is an important obstacle for socioeconomic development and food security. Under such circumstances, wastewater reuse in agriculture can be regarded an important alternative water source. However, treated wastewater may contain some types of pathogenic microorganisms which can threaten human health. In the present study we compared the impacts of treated wastewater (TWW) and tap water irrigation on microbiological quality of soil and crops (maize and maize leaves) through a furrow irrigation system in an experimental field. Materials and Methods: Total and fecal coliforms and Escherichia coliwere monitored as indicator bacteria in TWW, irrigated soil and harvested maize and maize leaves. We investigated the presence of Salmonellaand Shigellaby using a combination of culture and molecular methods. Statistical analyses were performed by SPSS 22.0 software. P

The data we present are part of the AGRO-ECOSERVICES project (Assessing ecosystem services and disservices provided by arthropod species in Azorean agroecosystems). The project aims to evaluate the relative importance of native and non-native organisms as ecosystem services (ES) and disservices (ED) providers, by combining novel, direct and quantitative tools for monitoring agro-biodiversity. Ecosystem services include evaluation of natural pest control by predation, seed predation on weed plants, pollination, decomposition and ecosystem disservices, herbivory and seed predation on crop plants. Active Aerial Searching (AAS) (only in maize-fields) and pitfall traps were used to sample the arthropod biodiversity (predatory spiders, true-bugs and beetles and main insect pests) on four agricultural habitats of Terceira Island, namely citrus orchards, low and high elevation maize fields and vineyards. We provided an inventory of all arthropods recorded in four Azorean agroecosystems (citrus orchards, low and high elevation maize fields and vineyards) from Terceira Island. A total of 50412 specimens were collected, belonging to four classes, 20 orders, 81 families and 200 identified species of arthropods. A total of 127 species are considered introduced (n = 22646) and 69 native non-endemic (n = 24117). Four endemic species were recorded with very few specimens (n = 14) and 3635 specimens belong to unidentified taxa recorded only at genus or family level. Five species are new records for Terceira Island, with Lagria hirta (Linnaeus, 1758) (Coleoptera, Tenebrionidae) being also a new record for the Azores. This publication contributes to a better knowledge of the arthropods communities present in agro-ecosystems of Terceira Island and will serve as a baseline for future monitoring schemes targeting the long-term change in arthropod diversity and abundance.

ZmPTF1 regulates drought tolerance in maize by promoting root development and ABA synthesis, by binding to the G-box in the promoter and activating the expression of NCEDs, CBF4, NAC081, and NAC30., Drought stress is the most important environmental stress limiting maize production. ZmPTF1, a phosphate starvation-induced basic helix-loop-helix (bHLH) transcription factor, contributes to root development and low-phosphate tolerance in maize. Here, ZmPTF1 expression, drought tolerance, and the underlying mechanisms were studied by using maize ZmPTF1 overexpression lines and mutants. ZmPTF1 was found to be a positive regulator of root development, ABA synthesis, signalling pathways, and drought tolerance. ZmPTF1 was also found to bind to the G-box element within the promoter of 9-cis-epoxycarotenoid dioxygenase (NCED), C-repeat-binding factor (CBF4), ATAF2/NAC081, NAC30, and other transcription factors, and to act as a positive regulator of the expression of those genes. The dramatically upregulated NCEDs led to increased abscisic acid (ABA) synthesis and activation of the ABA signalling pathway. The up-regulated transcription factors hierarchically regulate the expression of genes involved in root development, stress responses, and modifications of transcriptional regulation. The improved root system, increased ABA content, and activated ABA-, CBF4-, ATAF2-, and NAC30-mediated stress responses increased the drought tolerance of the ZmPTF1 overexpression lines, while the mutants showed opposite trends. This study describes a useful gene for transgenic breeding and helps us understand the role of a bHLH protein in plant root development and stress responses.

Reallocating root biomass from nodal roots to lateral and early-emerging axial roots allows maize to capture more nitrogen under limiting conditions, including by increasing foraging at depth., Simulations indicated that reduced nodal root (NR) number (NRN) was promising for maize breeding, and were partially confirmed by relying on variation in NRN among inbreds. Using maize inbred line B73, experiments were conducted in hydroponics and tall mesocosms containing solid media with treatments involving no NR excision (0% NRE) or excising either 33% or 67% of the NRs as they emerged under high or low levels of nitrogen (N). Reduced NRN was hypothesized to increase elongation of all remaining root classes, N acquisition under low N, and shoot mass. Plants with 67% NRE had 12% and 19% less root mass fraction, 61% and 91% greater lateral to axial root length ratio regardless of N levels, and 61% and 182% greater biomass of embryonic roots under low N, compared with 0% NRE for hydroponics and mesocosms studies, respectively. Under low N in mesocosms, plants with 67% NRE had 52% greater shoot biomass, 450% greater root length at depth, and 232% greater deep-injected 15N content in the shoot relative to 0% NRE. These results reveal the mechanism by which plants with fewer NRs increase N capture and shoot mass by reallocation of biomass to lateral roots, embryonic roots, and first whorl NRs that increases foraging efficiency in solid media.

Maize plants grown in the presence of a mixed nitrate and ammonium supply exhibited rapid biomass accumulation associated with increased auxin biosynthesis and up-regulation of auxin-responsive transcripts, including those known to regulate cell expansion., The use of mixed nitrate and ammonium as a nitrogen source can improve plant growth. Here, we used metabolomics and transcriptomics to study the underlying mechanisms. Maize plants were grown hydroponically in the presence of three forms of nitrogen (nitrate alone, 75%/25% nitrate/ammonium, and ammonium alone). Plants grown with mixed nitrogen had a higher photosynthetic rate than those supplied only with nitrate, and had the highest leaf area and shoot and root biomass among the three nitrogen treatments. In shoot and root, the concentration of nitrogenous compounds (ammonium, glutamine, and asparagine) and carbohydrates (sucrose, glucose, and fructose) in plants with a mixed nitrogen supply was higher than that with nitrate supply, but lower than that with ammonium supply. The activity of the related enzymes (glutamate synthase, asparagine synthase, phosphoenolpyruvate carboxylase, invertase, and ADP-glucose pyrophosphorylase) changed accordingly. Specifically, the mixed nitrogen source enhanced auxin synthesis via the shikimic acid pathway, as indicated by the higher levels of phosphoenolpyruvate and tryptophan compared with the other two treatments. The expression of corresponding genes involving auxin synthesis and response was up-regulated. Supply of only ammonium resulted in high levels of glutamine and asparagine, starch, and trehalose hexaphosphate. We conclude that, in addition to increased photosynthesis, mixed nitrogen supply enhances leaf growth via increasing auxin synthesis to build a large sink for carbon and nitrogen utilization, which, in turn, facilitates further carbon assimilation and nitrogen uptake.

A two-gene co-expression strategy to increase the folate precursors pterin and p-aminobenzoate increases the levels of folates in wheat and maize grains., Folates are indispensable co-factors for one-carbon metabolism in all organisms. In humans, suboptimal folate intake results in serious disorders. One promising strategy for improving human folate status is to enhance folate levels in food crops by metabolic engineering. In this study, we cloned two GmGCHI (GTP cyclohydrolase I) genes (Gm8gGCHI and Gm3gGCHI) and one GmADCS (aminodeoxychorismate synthase) gene from soybean, which are responsible for synthesizing the folate precursors pterin and p-aminobenzoate, respectively. We initially confirmed their functions in transgenic Arabidopsis plants and found that Gm8gGCHI increased pterin and folate production more than Gm3gGCHI did. We then co-expressed Gm8gGCHI and GmADCS driven by endosperm-specific promoters in maize and wheat, two major staple crops, to boost their folate metabolic flux. A 4.2-fold and 2.3-fold increase in folate levels were observed in transgenic maize and wheat grains, respectively. To optimize wheat folate enhancement, codon-optimized Gm8gGCHI and tomato LeADCS genes under the control of a wheat endosperm-specific glutenin promoter (1Dx5) were co-transformed. This yielded a 5.6-fold increase in folate in transgenic wheat grains (Gm8gGCHI+/LeADCS+). This two-gene co-expression strategy therefore has the potential to greatly enhance folate levels in maize and wheat, thus improving their nutritional value.

The mitochondrial PPR protein EMP12 is required for the splicing of cis- and trans-introns of nad2, complex I biogenesis, and seed development in maize., Plant mitochondrial genes contain cis- and trans-group II introns that must be spliced before translation. The mechanism by which these introns are spliced is not well understood. Several families of proteins have been implicated in the intron splicing, of which the pentatricopeptide repeat (PPR) proteins are proposed to confer the substrate binding specificity. However, very few PPRs are characterized. Here, we report the function of a P-type PPR protein, EMP12, and its role in seed development. EMP12 is targeted to mitochondria. Loss-of-function mutation in Emp12 severely arrests embryo and endosperm development, causing embryo lethality. The trans-splicing of mitochondrial nad2 intron 2 and cis-splicing of nad2 intron 4 are abolished, whereas the cis-splicing of nad2 intron 1 is reduced in emp12 mutants. As a result, complex I assembly is disrupted, and its activity is strongly reduced in the mutants. The expression of the alternative oxidase and several components of other mitochondrial complexes is increased, possibly in response to the defective complex I. These results suggest that Emp12 is required for the trans-splicing of nad2 intron 2 and cis-splicing of nad2 introns 1 and 4, and is important to complex I biogenesis, and embryogenesis and endosperm development in maize.

The volume of bundle sheath chloroplasts available for Rubisco investment in the leaves of four C4 grasses could potentially support much greater photosynthetic activity than is typically observed, even at chilling temperature., C4 leaves confine Rubisco to bundle sheath cells. Thus, the size of bundle sheath compartments and the total volume of chloroplasts within them limit the space available for Rubisco. Rubisco activity limits photosynthesis at low temperatures. C3 plants counter this limitation by increasing leaf Rubisco content, yet few C4 species do the same. Because C3 plants usually outperform C4 plants in chilling environments, it has been suggested that there is insufficient chloroplast volume available in the bundle sheath of C4 leaves to allow such an increase in Rubisco at low temperatures. We investigated this potential limitation by measuring bundle sheath and mesophyll compartment volumes and chloroplast contents, as well as leaf thickness and inter-veinal distance, in three C4 Andropogoneae grasses: two crops (Zea mays and Saccharum officinarum) and a wild, chilling-tolerant grass (Miscanthus × giganteus). A wild C4 Paniceae grass (Alloteropsis semialata) was also included. Despite significant structural differences between species, there was no evidence of increased bundle sheath chloroplast volume per leaf area available to the chilling-tolerant species, relative to the chilling-sensitive ones. Maximal theoretical photosynthetic capacity of the leaf far exceeded the photosynthetic rates achieved even at low temperatures. C4 bundle sheath cells therefore have the chloroplast volume to house sufficient Rubisco to avoid limiting C4 photosynthesis during chilling.

Purple corn is a maize variety (Zea mays L.) with high anthocyanin content. When purple corn is used as forage, its anthocyanins may mitigate oxidative stresses causing lower milk production in dairy cows. In this study, we analyzed quantitative trait loci (QTLs) for anthocyanin pigmentation of maize organs in an F2 population derived from a cross between the Peruvian cultivar ‘JC072A’ (purple) and the inbred line ‘Ki68’ (yellowish) belonged to Japanese flint. We detected 17 significant QTLs on chromosomes 1–3, 6, and 10. Because the cob accounts for most of the fresh weight of the plant ear, we focused on a significant QTL for purple cob on chromosome 6. This QTL also conferred pigmentation of anther, spikelet, leaf sheath, culm, and bract leaf, and was confirmed by using two F3 populations. The gene Pl1 (purple plant 1) is the most likely candidate gene in this QTL region because the amino acid sequence encoded by Pl1-JC072A is similar to that of an Andean allele, Pl-bol3, which is responsible for anthocyanin production. The markers designed for the Pl1 alleles will be useful for the breeding of F1 lines with anthocyanin pigmentation in cobs.

Objective:We hypothesise that exposure to aflatoxins and fumonisins, measured in serum, alters protein synthesis, reducing serum protein and insulin-like growth factor 1 (IGF-1), increasing inflammation and infection, leading to child’s linear growth failure.Design:Children 6–35 months, stratified by baseline stunting, were subsampled from an intervention trial on quality protein maize consumption and evaluated at two time-points.Setting:Blood samples and anthropometric data were collected in the pre-harvest (August–September 2015) and post-harvest (February 2016) seasons in rural Ethiopia.Participants:102 children (50 stunted and 52 non-stunted).Results:Proportions of children exposed to aflatoxin G1, aflatoxin G2 and aflatoxin M1 were higher in the pre-harvest (8, 33 and 7, respectively) compared to post-harvest season (4, 28 and 4, respectively). The proportion of children exposed to any aflatoxin was higher in the pre-harvest than post-harvest season (51 % v. 41 %). Fumonisin exposure ranged from 0 % to 11 %. In joint statistical tests, aflatoxin exposure was associated with serum biomarkers of inflammation (C-reactive protein, α-1-glycoprotein) and protein status (transthyretin, lysine, tryptophan), IGF-1 and linear growth (all P < 0·01). However, exposure to specific aflatoxins was not significantly associated with any biomarkers or outcomes (all P > 0·05).Conclusions:Aflatoxin exposure among rural Ethiopian children was high, with large variation between seasons and individual aflatoxins. Fumonisin exposure was low. There was no clear association between aflatoxin exposure and protein status, inflammation or linear growth. A larger study may be needed to examine the potential biological interactions, and the assessment of aflatoxins in food is needed to determine sources of high exposure.