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PubMed2004

Nucleotide diversity of the ZmPox3 maize peroxidase gene: relationships between a MITE insertion in exon 2 and variation in forage maize digestibility.

BACKGROUND: Polymorphisms were investigated within the ZmPox3 maize peroxidase gene, possibly involved in lignin biosynthesis because of its colocalization with a cluster of QTL related to lignin content and cell wall digestibility. The purpose of this study was to identify, on the basis of 37 maize lines chosen for their varying degrees of cell wall digestibility and representative of temperate regions germplasm, ZmPox3 haplotypes or individual polymorphisms possibly associated with digestibility. RESULTS: Numerous haplotypes with high diversity were identified. Frequency of nucleotide changes was high with on average one SNP every 57 bp. Nucleotide diversity was not equally distributed among site categories: the estimated pi was on average eight times higher for silent sites than for non-synonymous sites. Numerous sites were in linkage disequilibrium that decayed with increasing physical distance. A zmPox3 mutant allele, carrying an insertion of a transposable element in the second exon, was found in lines derived from the early flint inbred line, F7. This element possesses many structural features of miniature inverted-repeat transposable elements (MITE). The mutant allele encodes a truncated protein lacking important functional sites. An ANOVA performed with a subset of 31 maize lines indicated that the transposable element was significantly associated with cell wall digestibility. This association was confirmed using an additional set of 25 flint lines related to F7. Moreover, RT-PCR experiments revealed a decreased amount of corresponding mRNA in plants with the MITE insertion. CONCLUSION: These results showed that ZmPox3 could possibly be involved in monolignol polymerisation, and that a deficiency in ZmPox3 peroxidase activity seemingly has a negative effect on cell wall digestibility. Also, genetic diversity analyses of ZmPox3 indicated that this peroxidase could be a relevant target for grass digestibility improvement using specific allele introgressions.

Base Sequence↗

PubMed1996

Development, acceptability, nutritional and physical characteristics of protein improved Nigerian abari (maize meal) prepared from soya and maize flours.

Soyabari in various blends namely A0 to A6 were produced from maize and soybean flours. The nutritional, physical and acceptability characteristics of the blends were investigated. The products were found to be superior to the customarily eaten Nigerian abari (maize meal) in terms of protein content and digestibility. With increasing level of soyflour supplementation of the maize flour, the overall balance of amino acid, available lysine, protein digestibility, total ash as well as energy density increased. Also firmer, smoother, lighter and more yellowish and attractive products were obtained as a result of supplementation. The blend produced at 30% level of supplementation was assessed similar in texture to cowpea moin-moin (cowpea meal). All blends were equally acceptable as the control abari but the blend produced from 40% soyflour supplementation was judged more similar in most characteristics to cowpea moin-moin. Blends A3 and A4 (30 and 40% level of soyflour supplementation respectively) are recommended for adoption based on its protein quality, physical and acceptability characteristics. The two formulations are suitable for combating protein malnutrition in a predominantly starch and cereal based diet.

Amino Acids↗

PubMed2005

Determination of type B fumonisin mycotoxins in maize and maize-based products by liquid chromatography/tandem mass spectrometry using a QqQlinear ion trap mass spectrometer.

A sensitive liquid chromatography/tandem mass spectrometry (LC/MS/MS) method for determining the type B fumonisin mycotoxins in corn-based foodstuffs is described. Fumonisins FB1 and FB2 were extracted from a 1 g sample by homogenization with acetonitrile/water (75:25, v/v, 50 mmol/L formic acid, 25 mL final volume) and the extract was defatted on C18 phase. Volumes of 5 mL of crude extracts were cleaned up on Carbograph-4 cartridges. The final solution was analyzed by HPLC with electrospray ionization mass spectrometry in positive ion mode using multiple reaction monitoring with a QqQ linear ion trap mass spectrometer. Recoveries for spiked corn-based foodstuffs ranged from 91-105% (RSD% < or =8%), and method detection limits were < or =2 ng/g for FB1 and < or =1 ng/g for FB2. Two different spiking levels were tested (5000 and 100 ng/g for FB1, 1000 and 20 ng/g for FB2). Quantitation was achieved by an external calibration procedure using matrix-matched standards, with diclofenac added post-cleanup as internal standard for the LC/MS/MS analyses. Calibration curves showed linearity in the concentration range 0.005-5 ng/microL of final extract (0.992 < or = R2< or =0.995). Two other fumonisins, FB3 and FB4, were identified in naturally contaminated samples of corn meal using an information-dependent acquisition protocol that looped three experiments, including neutral loss scan, enhanced resolution scan, and enhanced product ion scan. FB3 and FB4 quantitation was estimated as peak area ratios relative to the FB2 response in view of the lack of both standards. This work also includes an application of the present LC/MS/MS method to some maize and maize-based product samples (corn meal, cornflakes and popcorn) collected from Italian stores. FB1 and FB2 contamination levels exceeding the European Union recommendation were found in 8 out of 15 corn meal samples.

Chromatography, High Pressure Liquid↗

PubMed1993

Replication of maize streak virus mutants in maize protoplasts: evidence for a movement protein.

We have used protoplasts derived from a maize (Black Mexican Sweet) suspension culture to study the replication of maize streak virus (MSV) wild-type (wt) and mutant DNA genomes. Following inoculation with plasmids containing multimeric copies of MSV, both single-stranded (ss) and double-stranded MSV DNA forms were produced, in proportions relative to those seen in infected plants. The immunodetection of coat protein (PV2) and geminate particles confirmed that the protoplasts were able to support the entire multiplication cycle of MSV and therefore were suitable for the study of MSV gene function. Inoculation of protoplasts with V1 gene mutants which are unable to produce systemic infections in plants resulted in DNA replication and encapsidation indistinguishable from that obtained with wt constructs implicating the protein in virus movement. Computer analysis of the V1 protein (PV1) indicated a potential trans-membrane or membrane-embedded domain. Following inoculation of protoplasts with V2 mutants, ssDNA was not detected; the inability of these mutants to spread in plants may be due to a lack of ssDNA, PV2, or a combination of the two. The requirements for systemic infection of MSV are discussed.

Base Sequence↗

PubMed1995

Regulation of synthesis and turnover of maize auxin-binding protein and observations on its passage to the plasma membrane: comparisons to maize immunoglobulin-binding protein cognate.

Electrophysiological experiments have indicated that a fraction of the major auxin-binding protein (ABP1) of maize (Zea mays L.) might be a receptor on the outer surface of the plasma membrane. The predominant location of ABP1 is in the lumen of the endoplasmic reticulum (ER), in accord with its C-terminal KDEL retention signal. Little is known about the biology of the protein in vivo or the rate at which it might pass to the cell surface. We have examined the turnover of ABP1 by in vivo labelling of maize coleoptile sections. After different chase times, ABP1 was immunoprecipitated from detergent-solubilised membrane preparations. Two polypeptides coprecipitated with ABP1. Neither was recognised by any ABP1 antibodies nor by monoclonals to ER retention sequences. The possible significance of these coprecipitating polypeptides is discussed. In addition, we have used a monoclonal antibody to precipitate HDEL proteins from the same membrane preparations. Two dimensional electrophoresis and N-terminal sequencing showed that the major HDEL protein precipitated was a member of the heat-shock-protein 70 family, a homologue of BiP (immunoglobulin-binding protein). We have investigated the turnover of this BiP homologue for comparison with ABP1 and found that both had extended lifetimes, with half-lives greater than 24 h. Use of cordycepin to inhibit transcription indicated that ABP1 mRNA was also long-lived. Synthesis of ABP1 was strongly reduced by heat stress, was reduced a little in response to dithiothreitol and was not markedly changed by tunicamycin. In contrast, BiP synthesis increased markedly in response to tunicamycin and dithiothreitol and increased a little after heat stress.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗

PubMed2004

Detection and quantitation of genetically modified maize (Bt-176 transgenic maize) by applying ligation detection reaction and universal array technology.

We have applied the ligation detection reaction (LDR) combined with a universal array approach to the detection and quantitation of the polymerase chain reaction (PCR) amplified cry1A(b) gene from Bt-176 transgenic maize. We demonstrated excellent specificity and high sensitivity. Down to 0.5 fmol (nearly 60 pg) of PCR amplified transgenic material was unequivocally detected with excellent linearity within the 0.1-2.0% range with respect to wild-type maize. We suggest the feasibility of extending the LDR/universal array format to detect in parallel several transgenic sequences that are being developed for food applications.

Bacillus thuringiensis Toxins↗

PubMed2002

Effect of cowpea hay, groundnut hay, cotton seed meal and maize meal supplementation to maize stover on intake, digestibility, microbial protein supply and acetate kinetics in weaner lambs.

Ten weaner lambs were used in a double 5 x 5 Latin square design to evaluate the effect of supplementing maize stover (MS) with cowpea hay (CW), groundnut hay (GN), cotton seed meal (CSM) or maize meal (MM) on the intake, digestion kinetics and acetate clearance rate. CW and GN were offered at 30% w/w to MS, while CSM and MM were given at 15 g/kg0.75 per day. Supplementation reduced (p < 0.01) MS intake but enhanced (p < 0.01) total dry matter intake. There were no significant differences (p > 0.05) in digestibility. However, the estimated ME intake was significantly (p < 0.05) improved by supplementation. The estimated microbial protein supply was almost significantly (p < 0.06) improved by 22.68%, 5.35%, 17.58% and 47.90% on the CW-, GN-, CSM- and MM-supplemented diets, compared to the control (7.85 g/day). Microbial protein synthesis efficiency was not significantly affected (p > 0.05) by diet, and nor were the acetate clearance rates (p > 0.05), which averaged 0.0475 +/- 0.0078/min. The improvement in ME intake may have been due to a faster flow rate of digesta and a better balance of nutrients in the end-products of digestion. These results demonstrate that small amounts of forage supplements can improve nutrient intake when animals consume low-quality forages and provide a basis for comparing such supplements with bought-in protein and energy supplements.

Acetates↗

PubMed2002

Ruminal fermentation kinetics in ewes offered a maize stover basal diet supplemented with cowpea hay, groundnut hay, cotton seed meal or maize meal.

The effect on ruminal digestive kinetics of supplementing maize stover (MS) with cowpea hay (CW), groundnut hay (GN), cotton seed meal (CSM) or maize meal (MM) was evaluated in a 5 x 5 Latin square using five Merino ewes with ruminal cannulae. CW and GN were offered at 30% w/w to MS, while CSM and MM were given at 15 g/kg0.75 per day. There were significant time (p < 0.001) and time x diet (p < 0.05) effects on pH but the effect of diet alone was not significant (p > 0.05). There was a significant (p < 0.05) increase in the concentration of ammonia with time on the supplemented diets. There were no significant (p > 0.05) differences in the concentrations of total volatile fatty acids (VFAs). Butyrate increased with supplementation (p < 0.05). Supplementation increased the concentrations of branched-chain and total VFAs with time (p < 0.05). The non-glucogenic ratio was not significantly (p > 0.05) lower on supplemented diets owing to the higher butyrate concentration. The degradation curve constants were not significantly different (p > 0.05), the average effective dry matter degradation being 27.80% +/- 0.618% at 0.05 h-1 flow rate. The chemical and physical characteristics of the cell wall of MS may have presented few sites for microbial colonization, so limiting degradation. These results showed that small quantities of forage supplements can improve the ruminal environment in animals subsisting on low-quality forages and form a basis for comparison with bought-in protein and energy sources.

Ammonia↗

PubMed1993

Transgenic corn plants expressing MDMV strain B coat protein are resistant to mixed infections of maize dwarf mosaic virus and maize chlorotic mottle virus.

The maize dwarf mosaic virus strain B (MDMV-B) coat protein (cp) gene was cloned into a monocot expression cassette and introduced into sweet corn cell suspension cultures via particle bombardment or electroporation. Transformed cells were selected on culture media containing 300 mg/l kanamycin, and plants were regenerated. Cells from all transformed lines expressed the cp gene; and one transgenic line synthesized approximately 100-200 micrograms MDMV-cp per gram fresh weight. Plants regenerated from this line were challenged with a virus inoculum concentration adjusted to produce symptoms in nontransgenic controls at six days post inoculation. In growth chamber studies, the presence of the MDMV-cp provided resistance to inoculations with MDMV-A or MDMV-B and to mixed inoculations of MDMV and maize chlorotic mottle virus.

Base Sequence↗

PubMed1980

Preferential transcription of cloned maize chloroplast DNA sequences by maize chloroplast RNA polymerase.

Zea mays chloroplast DNA-dependent RNA polymerase in vitro preferentially transcribes maize chloroplast DNA sequences incorporated in cloned chimeric bacterial plasmids. Preferential transcription is dependent on the presence of a 27.5-kilodalton polypeptide, the S factor, which has been purified from maize chloroplasts, and also on the template's being in the supercoiled form.

Journal Article↗

PubMed1995

Abomasal glucose, maize starch and maize dextrin infusions in cattle: small-intestinal disappearance, net portal glucose flux and ileal oligosaccharide flow.

Three castrated male Holstein cattle (423 (SD 19)kg live weight) fitted with elevated carotid artery, portal, and mesenteric venous catheters, and abomasal and ileal cannulas were used to study small-intestinal starch digestion. The cattle were infused abomasally with water (275 ml/h), glucose (66 g/h), maize dextrin (66 g/h) or maize starch (66 g/h) in an incomplete Latin square design, with eight infusion periods. Infusion with carbohydrate resulted in higher arterial glucose concentrations and greater net portal glucose flux than when cattle were infused with water. Arterial glucose concentration and net portal glucose flux were highest when glucose was infused. In the small intestine, 85% of abomasally-infused glucose, 78% of infused dextrin, and 66% of infused starch disappeared. Of the carbohydrate that disappeared in the small intestine, that which could be accounted for as net portal glucose flux was 73% for glucose, 60% for dextrin, and 57% for starch. Ileal digesta contained unpolymerized glucose, and short-chain soluble alpha-glucoside. Of the infused dextrin flowing past the ileum (14 g/h), 0.3 g/h was glucose, 6.2 g/h was soluble alpha-glucoside, and 7.5 g/h was insoluble alpha-glucoside. Of the infused starch flowing at the ileum (22.2 g/h), 0.9 g/h was glucose, 5.3 g/h was soluble alpha-glucoside, and 15.9 g/h was insoluble alpha-glucoside. The average chain lengths of the soluble alpha-glucosides in ileal digesta were 2.07 and 2.36 for dextrin and starch infusions respectively, indicating mostly di- and to a lesser extent trisaccharides. We conclude that (1) when 66 g raw starch is presented to the small intestine per h, about half of the intestinal disappearance appears as glucose in the portal vasculature, and (2) alpha-1,4 glucosidase (EC 3.2.1.20) activity at the brush border is the rate-limiting step to small-intestinal starch digestion in cattle.

Abomasum↗

PubMedDate not supplied

Investigation of the presence of biogenic amines and ethyl carbamate in kenkey made with maize and maize-cowpea mixtures as influenced by process conditions.

Kenkey is a fermented and cooked maize dough from Ghana. The effect of manufacturing conditions, i.e. fermentation and cooking, and of protein-enrichment by cowpea addition (20% of total weight) on the occurrence of toxic microbial products, namely biogenic amines and ethyl carbamate, were investigated. The levels of biogenic amines in all-maize kenkey were very low (total amines < 60 ppm), but were significantly increased by addition of red cowpea (total amines < 200 ppm, mainly cadaverine and tyramine), and even more by white cowpea (total amines < 500 ppm, mainly putrescine and tyramine). Histamine was absent (< 5 ppm) in all samples. The effects of fermentation and cooking were less pronounced than the influence of cowpea addition. Prolonged cooking of kenkey resulted in lower levels of putrescine, but did not significantly reduce tyramine levels. Ethyl carbamate levels were negligible (< 11 ppb) in all treatments.

Biogenic Amines↗

PubMed1991

Photoregulation of the Cat2 and Cat3 catalase genes in pigmented and pigment-deficient maize: the circadian regulation of Cat3 is superimposed on its quasi-constitutive expression in maize leaves.

We have investigated the accumulation of Cat2 and Cat3 catalase transcripts in 6-7-day postimbibition leaves of normally pigmented and pigment-deficient maize seedlings under different light regimes. In seedlings of normal inbred maize lines Cat2 mRNA accumulates to significantly higher levels in either continuous light or a diurnal light/dark cycle than in continuous dark. In contrast to the high levels of the Cat2 message observed in their wild-type siblings, carotenoid-deficient mutants accumulate Cat2 mRNA at barely detectable levels. Mutants deficient in chlorophylls, but having normal carotenoid levels, accumulate normal levels of Cat2 mRNA. This suggests that both light and carotenoids are required for the normal accumulation of the Cat2 message. The steady-state level of Cat3 RNA exhibits a dramatic diurnal variation when seedlings are grown under a 24-hr light/dark cycle. We have previously shown that this variation is at the level of Cat3 gene transcription and is under the control of a novel circadian rhythm. In this study we show that both pigment-deficient mutants and their wild-type siblings exhibit the normal diurnal pattern of Cat3 RNA accumulation. This indicates that photosynthetic pigments, allelic variation, and genetic background do not directly affect the temporal pattern of Cat3 accumulation in leaves. We observed, however, that when normal plants are grown in either continuous light or continuous dark, the Cat3 transcript in leaves is present at uniformly high levels throughout the 24-hr sampling period.(ABSTRACT TRUNCATED AT 250 WORDS)

Blotting, Northern↗

PubMed1997

The maize pathogenesis-related PRms protein localizes to plasmodesmata in maize radicles.

Pathogenesis-related (PR) proteins are plant proteins induced in response to infection by pathogens. In this study, an antibody raised against the maize PRms protein was used to localize the protein in fungal-infected maize radicles. The PRms protein was found to be localized at the contact areas between parenchyma cells of the differentiating protoxylem elements. By using immunoelectron microscopy, we found that these immunoreactive regions correspond to plasmodesmal regions. This was also true for the parenchyma cells filling the central pith of the vascular cylinder, although PRms mRNA accumulation was not detected in these cells. These findings suggest that for one cell type, the parenchyma cells of the central pith, the protein is imported rather than synthesized. The localization of the PRms protein indicates the possible existence of mechanisms for sorting of plant proteins to plasmodesmata and suggests that this protein may have a specialized function in the plant defense response. These findings are discussed with respect to the structure and function of plasmodesmata in cell-to-cell communication processes in higher plants.

Fusarium↗

PubMed1994

In vivo aggregation of maize Activator (Ac) transposase in nuclei of maize endosperm and Petunia protoplasts.

The transposase (TPase) of the maize transposon Activator (Ac) accumulates in the nuclei of maize endosperm and transfected Petunia protoplasts, where it aggregates into rod-like structures about 2 microm in length. In petunia protoplasts the amount of TPase aggregates increases with the strength of the promoter fused to the Ac-coding region. The excision frequency of a Ds element, however, does not increase proportionally. The data suggest that the aggregated TPase is not responsible for the mobilization of the Ds element, but rather is a transpositionally inactive form of the protein. In contrast to the full-length TPase, a functional, N-terminally truncated TPase derivative is inefficiently transported into the nucleus at high expression levels and aggregates predominantly in the cytoplasm. Accordingly, the N-terminus of the TPase is involved in nuclear localization and/or aggregation.

Amino Acid Sequence↗

PubMed2006

Analysis of sugarcane mosaic virus resistance in maize in an isogenic dihybrid crossing scheme and implications for breeding potyvirus-resistant maize hybrids.

The gene action of 2 sugarcane mosaic virus (SCMV) resistance loci in maize, Scmv1 and Scmv2, was evaluated for potyvirus resistance in an isogenic background. All 4 homozygous and 5 heterozygous isogenic genotypes were produced for introgressions of the resistant donor (FAP1360A) alleles at both loci into the susceptible parent (F7) genetic background using simple sequence repeat markers. For SCMV and maize dwarf mosaic virus (MDMV), virus symptoms appeared rapidly in the 3 homozygous genotypes, with susceptibility alleles fixed at 1 or both loci. Although the 9 isogenic genotypes revealed a high level of resistance to Zea mosaic virus (ZeMV), the same 3 homozygous genotypes were only partially resistant. This indicates that 1 resistance gene alone is not sufficient for complete resistance against SCMV, MDMV, and ZeMV. Scmv1 showed strong early and complete dominant gene action to SCMV, but it gradually became partially dominant. Scmv2 was not detected at the beginning, showing dominant gene action initially and additive gene action at later stages. Both genes interacted epistatically (for a high level of resistance, at least 1 resistance allele at each of both loci is required). This implies that double heterozygotes at the 2 loci are promising for producing SCMVresistant hybrids. Results are discussed with respect to prospects for isolation of SCMV and MDMV resistance genes.

Breeding↗

PubMedDate not supplied

Determination of zearalenone in barley, maize and wheat flour, polenta, and maize-based baby food by immunoaffinity column cleanup with liquid chromatography: interlaboratory study.

An interlaboratory study was performed on behalf of the UK Food Standards Agency to evaluate the effectiveness of an affinity column cleanup liquid chromatography (LC) method for the determination of zearalenone (ZON) in a variety of cereals and cereal products at proposed European regulatory limits. The test portion is extracted with acetonitrile:water. The sample extract is filtered, diluted, and applied to an affinity column. The column is washed, and ZON is eluted with acetonitrile. ZON is quantified by reversed-phase LC with fluorescence detection. Barley, wheat and maize flours, polenta, and a maize-based baby food naturally contaminated, spiked, and blank (very low level) were sent to 28 collaborators in 9 European countries and 1 collaborator in New Zealand. Participants were asked to spike test portions of all samples at a ZON concentration equivalent to 100 microg/kg. Average recoveries ranged from 91-111%. Based on results for 4 artificially contaminated samples (blind duplicates) and 1 naturally contaminated sample (blind duplicate), the relative standard deviation for repeatability (RSDr) ranged from 6.9-35.8%, and the relative standard deviation for reproducibility (RSDR) ranged from 16.4-38.2%. The method showed acceptable within- and between-laboratory precision for all 5 matrixes, as evidenced by HorRat values <1.7.

Calibration↗

PubMed2001

Investigation of the potential of maize streak virus to act as an infectious gene vector in maize plants.

There has been a great deal of interest in the possibility that geminiviruses might be used as infectious gene vectors for expression of foreign proteins in plants. However, generic mastreviruses such as Maize streak virus (MSV) have no sequences which are dispensable for systemic infection of plants, and there is a strict limitation on the size of viral DNA which can be moved systemically. We attempted to complement the movement functions deleted from a wild-type-sized, replication-proficient gene replacement vector, by co-infecting plants with it and either wild type MSV, or a replication-deficient but putatively movement-proficient viral construct. While ssDNA formation by the gene replacement vector could be complemented in trans by co-transfected wild type virus, true systemic movement of either the vector, or of co-complementing constructs, did not occur. However, recombination between the two complementing viral constructs frequently occurred to generate wild-type virus genomes. The results therefore suggest that formation of ssDNA and size of the viral replicon are not the sole determinants of whether the MSV movement proteins can mobilise viral sequences and move them systemically in plants.

Blotting, Southern↗