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PubMed2004

Transmission of maize chromosome 9 rearrangements in oat-maize radiation hybrids.

Oat-maize radiation hybrids are oat (Avena sativa L.) plants carrying radiation-induced subchromosome fragments of a given maize (Zea mays L.) chromosome. Since first-generation radiation hybrids contain various maize chromosome rearrangements in a hemizygous condition, variation might be expected in the transmission of these rearrangements to subsequent generations. The transmission and integrity of maize chromosome 9 rearrangements were evaluated in progenies of 30 oat-maize radiation hybrids by using a series of DNA-based markers and by genomic in situ hybridization. Maize chromosome 9 rearrangements were reisolated by self-fertilization in 24 of the 30 radiation hybrid lineages. Normal and deleted versions of maize chromosome 9 were transmitted at similar frequencies of 9.1% and 7.6%, respectively, while intergenomic translocations were transmitted at a significantly higher frequency of 47.6%. Most lines (93%) that inherited a rearrangement had it in the hemizygous condition. Lines with a rearrangement in the homozygous state (7%) were only identified in lineages with intergenomic translocations. Homozygous lines are more desirable from the perspective of stock maintenance, since they may stably transmit a given rearrangement to a subsequent generation. However, their isolation is not strictly required, since hemizygous lines can also be used for genome mapping studies.

Avena↗

PubMed2005

Aflatoxin levels in maize and maize products during the 2004 food poisoning outbreak in Eastern Province of Kenya.

BACKGROUND: On 10th May, 2004 food samples suspected to have caused acute poisoning in Makueni district were received at the National Public Health Laboratory Services (NPHLS). On analysis, they were found to be highly contaminated with aflatoxin B1. More cases of poisoning were reported in the district and in neighbouring districts of Kitui, Machakos and Thika. As at 20th July, 2004 the Ministry of Health was aware of 317 cases of which 125 resulted in deaths. OBJECTIVE: To assess the magnitude of aflatoxin contamination of maize and maize products in the affected areas. DESIGN: Random environmental sampling of maize and maize products and case/control samples of the same in the affected regions and subsequent determination of aflatoxin levels using immunoaffinity coupled with solution fluorometry. SETTING: National Public Health Laboratory Services, Ministry of Health, Kenya, from May to August, 2004. SUBJECTS: A total of 480 samples comprising 362 random environmental samples, 26 cases and 92 controls were collected and analysed. The foods analysed included maize grains, maize flour and dehulled dry maize, traditionally known as muthokoi. RESULTS: Forty six point four per cent of the environmental samples, 15% of cases and 29.3% of controls were within the maximum permissible limit of 20 microg implying that over 50% (54.4) of the total did not comply and would be regarded as unfit for human consumption. 6.9% of the environmental samples, 57.7% of cases and 21.7 of controls had levels beyond 1000 microg/Kg. The amount of aflatoxin observed in the food samples had a range of 0-58,000 microg/Kg. CONCLUSION: The population in the affected region was exposed to high levels of aflatoxin. There is need to address the issue of pre and post harvest handling of grain and establishing monitoring and surveillance for early detection and intervention.

Acute Disease↗

PubMed2004

Fate of maize intrinsic and recombinant genes in calves fed genetically modified maize Bt11.

The presence of maize intrinsic and recombinant cry1Ab genes in the gastrointestinal (GI) contents, peripheral blood mononuclear cells (PBMC), and visceral organs of calves fed genetically modified Bt11 maize was examined by PCR in a subchronic 90-day performance study. Samples were collected from six Japanese Black/Holstein calves fed Bt11 maize and from six calves fed non-Bt maize. Fragments of maize zein (Ze1), invertase, chloroplast, and cry1Ab were detected inconsistently in the rumen fluid and rectal contents 5 and 18 h after feeding. The chloroplast DNA fragments of ribulose-1,5-bisphosphate carboxylase/oxygenase and tRNA were detected inconsistently in the PBMC, the visceral organs, and the longissimus muscle, while the cry1Ab gene was never detected in PBMC or in the visceral organs. These results suggest that feed-derived maize DNA was mostly degraded in the GI tract but that fragmented DNA was detectable in the GI contents as a possible source of transfer to calf tissues. These results also suggest that the recombinant cry1Ab genes were not transferred to the PBMC and tissues of calves fed Bt11 maize.

Animal Feed↗

PubMed2001

Primus (florasulam 50 G/L), a new triazolopyrimidine sulfonanilide herbicide to control broad-leaved weeds in maize when applied in early postemergence (1 to 6 leaf stage of maize). Preliminary results.

OBJECTIVE: PRIMUS was developed in maize in Belgium in 1999 and 2000 in the course of research into limiting or replacing the use of triazines in maize. One of the imperatives of this research was to find the lowest possible residue content (MRL). SELECTIVITY TEST: An application of florasulam, at the dose of 5 g of active substance (a.s.) at the 2 to 3 leaf stage of the maize was found to be selective on 132 (in 1999) and 126 (in 2000) varieties of maize. EFFICACY TEST: Florasulam was tested at doses of between 1 and 5 g a.s./hectare. The treatments were applied in early postemergence at the 3-5 leaf stage of the maize or in 2 separate applications: at the 1 leaf stage with a dose of 2 g a.s. florasulam at the 4 leaf stage with a dose of 2 g a.s. florasulam The herbicide was fully effective on the sensitive flora. A summary of the results is presented. A detailed weed spectrum is defined. PROGRAMMES: Herbicide programmes were developed on the basis of these findings. The results showed that the best partners for florasulam were triketones (sulcotrione and mesotrione) in very low doses. Sulcotrione was applied at doses of 75 to 150 g a.s./ha and mesotrione at 25 to 50 g a.s./ha. Triple mixes of florasulam + triketone + nicosulfuron in very low doses and 1 or 2 applications were also tested. The results were highly encouraging and this work should lead to practical recommendations. PHYTOTOXICITY: Phytotoxicity was observed on some occasions. The phytotoxicity results for the different figures seem, however, to depend more on the climate (difference between daytime and night-time temperatures just before and after the treatment) than on the products tested in the mixes. However, the florasulam + nicosulfuron (sulfonyl-urea antigrasses) may sometimes cause serious problems with selectivity. The phytotoxicity noted in the tests was usually short-lived (30 days). CONCLUSION: The results of the tests show that it is possible to consider replacing atrazine-based programmes with very low doses of modern herbicides applied at early stages of the maize. A mixture of active substances is vital. Repeated very low doses at the 1/2 and 4/5 leaf stages of the maize were found to be the most effective.

Cyclohexanones↗

PubMed2002

Characterisation of the expression of a novel constitutive maize promoter in transgenic wheat and maize.

A novel constitutive promoter from the maize histone H2Bgene was recently identified. In this study, we characterised H2B promoter activity in both wheat and maize tissues using the gusA reporter gene and two synthetic versions of the pat (phosphinothricin acetyl transferase) selectable marker gene, namely mopat and popat. Analyses of transgenic plants showed that the H2B promoter is able to drive the expression of gusA to strong, constitutive levels in wheat and maize tissues. Using an H2B:mopat construct and phosphinothricin selection, we recovered transgenic wheat plants at efficiencies ranging from 0.3% to 7.4% (mean 1.6%), and the efficiency of selection ranged from 40% to 100% (mean 77.7%). In another application, H2B was combined with the maize Ubi-1 or the maize Adh-1 intron to drive the expression of mopat and popat. Transformation efficiencies with the Ubi-1 intron were between 1.4- to 16-fold greater than with the Adh-1 intron. However, the use of either of the introns was necessary for the recovery of transgenic plants. Mopat gave higher transformation efficiencies and induced higher levels of PAT protein in maize tissues than popat.

Acetyltransferases↗

PubMed2006

Down-regulation of the maize and Arabidopsis thaliana caffeic acid O-methyl-transferase genes by two new maize R2R3-MYB transcription factors.

The maize (Zea mays L.) caffeic acid O-methyl-transferase (COMT) is a key enzyme in the biosynthesis of lignin. In this work we have characterized the involvement of COMT in the lignification process through the study of the molecular mechanisms involved in its regulation. The examination of the maize COMT gene promoter revealed a putative ACIII box, typically recognized by R2R3-MYB transcription factors. We used the sequence of known R2R3-MYB factors to isolate five maize R2R3-MYB factors (ZmMYB2, ZmMYB8, ZmMYB31, ZmMYB39, and ZmMYB42) and study their possible roles as regulators of the maize COMT gene. The factors ZmMYB8, ZmMY31, and ZmMYB42 belong to the subgroup 4 of the R2R3-MYB family along with other factors associated with lignin biosynthesis repression. In addition, the induction pattern of ZmMYB31 and ZmMYB42 gene expression on wounding is that expected for repressors of the maize COMT gene. Arabidopsis thaliana plants over-expressing ZmMYB31 and ZmMYB42 down-regulate both the A. thaliana and the maize COMT genes. Furthermore, the over-expression of ZmMYB31 and ZmMYB42 also affect the expression of other genes of the lignin pathway and produces a decrease in lignin content of the transgenic plants.

Amino Acid Sequence↗

PubMed2001

A maize insulin-like growth factor signals to a transduction pathway that regulates protein synthesis in maize.

Insulin and insulin-like growth factors (IGFs) are well-characterized regulators in higher eukaryotic cells that control biological processes such as cell growth and survival, and selective translation of mRNAs. This research presents the purification of a 20 kDa protein, isolated from maize tissue, with IGF activity. The protein was purified from 48 h-germinated maize embryonic axes by G-50 Sephadex fractionation followed by affinity chromatography through a bovine insulin antibody-Sepharose column. This protein proved to significantly speed up maize germination and seedling growth. At the molecular level, Zea mays IGF (ZmIGF) enhanced phosphorylation of S6 ribosomal protein (rp) on the 40 S ribosomal subunit, in a similar way as observed when bovine insulin is applied to maize axes during germination. Rapamycin, a specific inhibitor of the insulin-stimulated signal transduction pathway, prevented S6 rp phosphorylation in maize axes. Moreover, ZmIGF stimulated [(35)S]methionine incorporation into rps, above the level of overall cytoplasmic proteins. Either incubation with anti-insulin antibody, heat treatment (60 degrees C) or trypsin digestion abolished this ZmIGF effect. It is proposed that ZmIGF is an endogenous maize growth factor that regulates the synthesis of specific proteins through a pathway similar to that of insulin or IGFs in animal tissues.

Animals↗

PubMed1991

Maize oleosin is correctly targeted to seed oil bodies in Brassica napus transformed with the maize oleosin gene.

Oleosins are small hydrophobic abundant proteins localized in the oil bodies of plant seeds. An oleosin gene from the monocotyledonous maize (Zea mays L.) was transferred into the dicotyledonous Brassica napus L. using Agrobacterium-mediated transformation. The maize oleosin gene was placed under the control of either its own promoter/terminator or the promoter/terminator of a Brassica seed storage protein (napin) gene. Southern blot analyses of individual transformed plants suggested that the oleosin gene from either construct was incorporated into the Brassica chromosomes without appreciable structural alterations. The amount of construct incorporated was from 1 to >10 copies per haploid genome, depending on the individual transformant. Maize oleosin mRNA and protein were detected only in the transformants containing the napin gene promoter/terminator constructs; these transformants were studied further. Northern blot analyses of RNA isolated from different tissues and seeds of different developmental stages indicated that the maize oleosin mRNA was present only in the maturing seed. Approximately 1% of the total protein in mature seed was represented by maize oleosin. Subcellular fractionation of the mature seed revealed that 90% or more of the maize oleosin, as well as the Brassica oleosin, was localized in the oil bodies. The results show that a monocotyledonous oleosin possesses sufficient targeting information for its proper intracellular transport in a dicotyledon and also suggest that the napin gene promoter/terminator of Brassica, or equivalent seed storage protein regulatory elements of other plant species, may be used to express genes for the genetic engineering of seed oils.

Journal Article↗

PubMed2000

The promoter for the maize C4 pyruvate, orthophosphate dikinase gene directs cell- and tissue-specific transcription in transgenic maize plants.

The pyruvate,orthophosphate dikinase (PPDK) gene coding the chloroplast enzyme involved in C4 photosynthesis has a dual promoter system. The first promoter is responsible for the transcription of a larger transcript and its product is targeted to the chloroplast (hence, it is designated as C4Pdk promoter) while the second promoter is responsible for the transcription of a smaller transcript and its product remains in the cytosol. In this study, chimeric maize C4Pdk promoter (0.9 or 1.5 kb)-beta-glucuronidase or luciferase fusion genes were introduced into maize plants by Agrobacterium-mediated transformation. The cell- and tissue-specificities of the maize C4Pdk promoter in the transgenic maize plants were examined by histochemical and enzymic activity analyses of the reporters in different photosynthetic cells and tissues. The results showed that the reporter proteins are almost exclusively localized in leaf mesophyll cells. Among the tissues tested, leaf blade had the highest reporter activities with sheath exhibiting about 10% of the activities in blade. Husk, stem, tassel and root had no or very little reporter activities. Taken together, these results suggest that the maize C4Pdk promoter is specifically transcribed in the mesophyll cells of leaf blade and to a much less extent in the mesophyll cells of sheath, but not in leaf bundle sheath cells or other tissues. Furthermore, the 0.9 kb maize C4Pdk promoter sequences appear to contain the necessary cis-acting elements for its cell- and organ-specific expression.

Gene Expression Regulation, Enzymologic↗

PubMed2005

Maize and oat antixenosis and antibiosis against Delphacodes kuscheli (Homoptera: Delphacidae), vector of "Mal de Rio Cuarto" of maize in Argentina.

"Mal de Rio Cuarto" (MRC) is the most important virus disease of maize, Zea mays L., in Argentina. Several maize lines show different levels of resistance to MRC in the field; however, no studies have been conducted to investigate resistance mechanisms against its insect vector, Delphacodes kuscheli Fennah (Homoptera: Delphacidae). Oat, Avena spp., is the main overwintering host of D. kuscheli and main source of populations that infest maize. Although oat varieties resistant to the greenbug, Schizaphis graminum (Rondani) (Homoptera: Aphididae) are commercially available, their effect on D. kuscheli is unknown. We conducted laboratory experiments to test for the presence of antixenosis and antibiosis resistance mechanisms on six maize lines with different levels of field resistance to MRC, and seven commercial oat cultivars that include two S. graminum-resistant varieties. We did not find antibiotic effects of maize lines on D. kuscheli longevity and survivorship patterns, but we obtained antixenotic effects from the LP2 line (field moderate) due to reduced settling preference and feeding. Oat 'Bonaerense Payé and 'Suregrain INTA' showed both antixenosis and antibiosis, with significantly less settling preference, oviposition in the no-choice test, and reduced total fecundity in comparison with the other varieties studied. The S. graminum-resistant 'Boyera F. A.' and 'Tambera F. A.' did not showed a consistent pattern of resistance versus D. kuscheli across all experiments. Our results indicate the presence of potential sources of insect resistance in the maize lines and oat cultivars tested that may be used in MRC integrated pest management programs.

Animals↗

PubMed2003

New strategy for the determination of gliadins in maize- or rice-based foods matrix-assisted laser desorption/ionization time-of-flight mass spectrometry: fractionation of gliadins from maize or rice prolamins by acidic treatment.

A procedure for determining small quantities of gliadins by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) in gluten-free foods containing relatively large amounts of prolamin proteins from maize or rice is described. We report for the first time that gliadins, the ethanol-soluble wheat prolamin fraction, can be quantitatively solubilized in 1.0 M acetic acid, while the corresponding ethanol-soluble maize or rice prolamin fraction remains insoluble in acetic acid. We describe a methodology for the detection of gliadins in maize and rice foods based on a two-step procedure of extraction (60% aqueous ethanol followed by 1 M acetic acid). Subsequent MALDI-TOFMS analysis of the resulting acidic extract from these gluten-free foods clearly confirms the presence of a typical mass pattern corresponding to gliadin components, ranging from 30 to 45 kDa. Depending on the percentages of maize or rice flours employed in the elaboration of these foods, the combined procedure enables levels of gliadins from 100 to 400 ppm to be detected. The efficiency of this combined procedure corroborates enzyme-linked immunosorbent assay data for a large number of maize/rice gluten-free foods by means of direct visualization of the characteristic gliadin mass pattern in maize or rice foods.

Food Analysis↗

PubMed1995

The maize GapC4 promoter confers anaerobic reporter gene expression and shows homology to the maize anthocyanin regulatory locus C1.

The cytosolic glyceraldehyde-3-phosphate dehydrogenase (GapC) gene family of maize is differentially expressed in response to anaerobic stress. While GapCl and GapC2 are downregulated, GapC3 and GapC4 are anaerobically induced. We have sequenced and analyzed a 3073 bp promoter fragment of GapC4. The promoter confers anaerobic induction of a reporter gene construct in a transient gene expression system in maize. Deletion analysis of the GapC4 promoter revealed a 270 bp long DNA region required for anaerobic induction. This region contains sequence motifs resembling the cis-acting sequences of the anaerobically induced maize Adh1 and Adh2 genes. Furthermore, the 3073 bp GapC4 promoter fragment displays homology to long terminal repeats of maize retrotransposons and to the 3' region of the maize anthocyanin regulatory locus C1.

Anaerobiosis↗

PubMed2002

Mixing of maize and wheat genomic DNA by somatic hybridization in regenerated sterile maize plants.

Intergeneric somatic hybridization was performed between albino maize ( Zea mays L.) protoplasts and mesophyll protoplasts of wheat ( Triticum aestivum L.) by polyethylene glycol (PEG) treatments. None of the parental protoplasts were able to produce green plants without fusion. The maize cells regenerated only rudimentary albino plantlets of limited viability, and the wheat mesophyll protoplasts were unable to divide. PEG-mediated fusion treatments resulted in hybrid cells with mixed cytoplasm. Six months after fusion green embryogenic calli were selected as putative hybrids. The first-regenerates were discovered as aborted embryos. Regeneration of intact, green, maize-like plants needed 6 months of further subcultures on hormone-free medium. These plants were sterile, although had both male and female flowers. The cytological analysis of cells from callus tissues and root tips revealed 56 chromosomes, but intact wheat chromosomes were not observed. Using total DNA from hybrid plants, three RAPD primer combinations produced bands resembling the wheat profile. Genomic in situ hybridization (GISH) using total wheat DNA as a probe revealed the presence of wheat DNA islands in the maize chromosomal background. The increased viability and the restored green color were the most-significant new traits as compared to the original maize parent. Other intermediate morphological traits of plants with hybrid origin were not found.

Journal Article↗

PubMed1999

Soil Type and Maize Cultivar Affect the Genetic Diversity of Maize Root-Associated Burkholderia cepacia Populations.

Abstract Burkholderia cepacia populations associated with the Zea mays root system were investigated to assess the influence of soil type, maize cultivar, and root localization on the degree of their genetic diversity. A total of 180 B. cepacia isolates were identified by restriction analysis of the amplified 16S rDNA (ARDRA technique). The genetic diversity among B. cepacia isolates was analyzed by the random amplified polymorphic DNA (RAPD) technique, using the 10-mer primer AP5. The analysis of molecular variance (AMOVA) method was applied to estimate the variance components for the RAPD patterns. The results indicated that, among the factors studied, the soil was clearly the dominant one in affecting the genetic diversity of maize root-associated B. cepacia populations. In fact, the percentage of variation among populations was significantly higher between B. cepacia populations recovered from maize planted in different soils than between B. cepacia populations isolated from different maize cultivars and from distinct root compartments such as rhizoplane and rhizosphere. The analysis of the genetic relationships among B. cepacia isolates resulted in dendrograms showing bacterial populations with frequent recombinations and a nonclonal genetic structure. The dendrograms were also in agreement with the AMOVA results. We were able to group strains obtained from distinct soils on the basis of their origin, confirming that soil type had the major effect on the degree of genetic diversity of the maize root-associated B. cepacia populations analyzed. On the other hand, strains isolated from distinct root compartments exhibited a random distribution which confirmed that the rhizosphere and rhizoplane populations analyzed did not significantly differ in their genetic structure.http://link.springer-ny.com/link/service/journals/00248/bibs/38n3p273.html</hea

Journal Article↗

PubMed2005

Consequences for Protaphorura armata (Collembola: Onychiuridae) following exposure to genetically modified Bacillus thuringiensis (Bt) maize and non-Bt maize.

Studies on the effect of genetically modified Bacillus thuringiensis (Bt) crops on true soil dwelling non-target arthropods are scarce. The objective of this study was to assess the influence of a 4-week exposure to two Bt maize varieties (Cry1Ab) Cascade and MEB307 on the collembolan Protaphorura armata. For comparison three non-Bt maize varieties, Rivaldo (isogenic to Cascade), Monumental (isogenic to MEB307) and DK242, and two control diets based on baker's yeast (uncontaminated and contaminated with Bt toxin Cry1Ab) were also tested. Due to a lower C:N ratio, individuals reared on yeast performed significantly better in all of the measured endpoints than those reared on maize. P. armata performed equally well when reared on two Bt and three non-Bt maize varieties. Although there were no negative effects of Bt maize in this experiment, we recommend future studies on Bt crops to focus on species interactions in long-term, multi-species experiments.

Animals↗

PubMed1998

Circadian expression of the maize catalase Cat3 gene is highly conserved among diverse maize genotypes with structurally different promoters.

The Cat3 gene of maize exhibits a transcriptionally regulated circadian rhythm. In the present study we examined the following: (1) the extent of the circadian Cat3 expression between maize genotypes of diverse origin; (2) the functional significance of a Tourist transposable element located in the Cat3 promoter of the inbred line W64A, which harbors putative regulatory elements (GATA repeat, CCAAT boxes) shown to be involved in the light induction and circadian regulation of the Arabidopsis CAB2, as well as other plant genes; and (3) aspects of the physiological role of CAT-3 in maize metabolism. Results confirm that the circadian Cat3 expression is a general phenomenon in maize. Regulation of Cat3 gene expression is not dependent on the presence of the Tourist element in the promoter of the gene nor on the presence of motifs similar to those found significant in the circadian expression of the Arabidopsis CAB2 gene. Structural diversity was revealed in the Cat3 promoters of maize genotypes of diverse origins. However, highly conserved regions with putative regulatory motifs were identified. Relevance of the conserved regions to the circadian regulation of the gene is discussed. Possible physiological roles of CAT-3 are suggested.

Arabidopsis Proteins↗

PubMed2005

The maize genetics and genomics database. The community resource for access to diverse maize data.

The Maize Genetics and Genomics Database (MaizeGDB) serves the maize (Zea mays) research community by making a wealth of genetics and genomics data available through an intuitive Web-based interface. The goals of the MaizeGDB project are 3-fold: to provide a central repository for public maize information; to present the data through the MaizeGDB Web site in a way that recapitulates biological relationships; and to provide an array of computational tools that address biological questions in an easy-to-use manner at the site. In addition to these primary tasks, MaizeGDB team members also serve the community of maize geneticists by lending technical support for community activities, including the annual Maize Genetics Conference and various workshops, teaching researchers to use both the MaizeGDB Web site and Community Curation Tools, and engaging in collaboration with individual research groups to make their unique data types available through MaizeGDB.

Base Sequence↗

PubMed1995

Maize ribosome-inactivating protein (b-32). Homologs in related species, effects on maize ribosomes, and modulation of activity by pro-peptide deletions.

The ribosome-inactivating protein (RIP) from maize (Zea mays L.) is unusual in that it is produced in the endosperm as an inactive pro-form, also known as b-32, which can be converted by limited proteolysis to a two-chain active form, alpha beta RIP. Immunological analysis of seed extracts from a variety of species related to maize showed that pro/alpha beta forms of RIP are not unique to maize but are also found in other members of the Panicoideae, including Tripsacum and sorghum. Ribosomes isolated from maize were quite resistant to both purified pro- and alpha beta maize RIPs, whereas they were highly susceptible to the RIP from pokeweed. This suggests that the production of an inactive pro-RIP is not a mechanism to protect the plant's own ribosomes from deleterious action of the alpha beta RIP. RIP derivatives with various pro-segments removed were expressed at high levels in Escherichia coli. Measurement of their activity before and after treatment with subtilisin Carlsberg clearly identified the 25-amino acid intradomain insertion, rather than the N- or C-terminal extensions, as the major element responsible for suppression of enzymatic activity. A RIP with all three processed regions deleted had activity close to that of the native alpha beta form.

Amino Acid Sequence↗