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PubMed1999

[Agrobacterium tumefaciens mediated maize transformation].

Several maize inbreds were transformed with Agrobacterium tumefaciens EHA101 (pGIH). Transgenic maize plants were obtained. Frequency of transformation of maize inbred Suyu No. 1 can reach 8.1%. Results of PCR and Southern blot analysis proved that T-DNA was stably integrated into the genome of maize. Staining with X-gluc confirmed the expression of GUS gene in maize cells. The band amplified by inverse PCR showed that the copy number of transgene in three transformants was single. After long term of subculture, some hygromycin resistant calli lost their regeneration ability. Although Southern blot probed the integration of gusA gene in their genome, GUS activity cannot be detected in those calli. Southern blot analysis of HpaII digest DNA showed that transgenic gusA gene was highly methylated.

Agrobacterium tumefaciens↗

PubMed2002

[Construction the RFLP linkage map and location the NCBL QTL of maize].

There exists the race differential phenomenon in Exserohilum turcicum (namely NCBL). At present, there are 5 identified races of NCBL and some un-known races in China. For improvement of maize resistance to NCBL, a basic method is to improve maize quantitative resistance. To identify the numbers and effects of the quantitative resistant loci to NCBL in maize, we constructed F2:3 population from resistant line P138 as male parent cross with sensitive line Z3 as female parent. Using RFLP marker technique, the RFLP linkage map of maize was cons cracted covering 1999. 8 cM, and the average distance between markers was 16.5 cM. Identified QTL of NCBL lesion length, width, and area were 3, 3, 2, respectively. The combined contribution ratios of these QTL were 58.1%, 71.5%, 27.5%, respectively. No QTL was identified NCBL lesion number per leaf, it was a trait that might be controlled by one- or oligo-genes. Finally, authors discussed and prospected the maize NCBL research in future.

Ascomycota↗

PubMed2003

Enhancement of development of larval Anopheles arabiensis by proximity to flowering maize (Zea mays) in turbid water and when crowded.

To determine whether proximity to flowering maize enhances the development of larval anopheline mosquitoes breeding in turbid water and when crowded, we evaluated the development of larval Anopheles arabiensis under various conditions of turbidity, larval density, and proximity to pollen-shedding maize in simulated breeding puddles in a malaria-endemic site. In naturally formed puddles, water turbidity, as well as larval density, increased as the rainy season progressed. In sites remote from flowering maize, more pupae developed and the resulting adults were larger in relatively clear water than in turbid water, and larval crowding inhibited development. In close proximity to flowering maize, however, larval development was little affected by water turbidity and larval crowding. Larvae of this member of the African An. gambiae complex of mosquitoes develop readily in turbid water and when crowded, provided that their breeding sites are located where maize pollen is abundant.

Animals↗

PubMed2003

[Soil nitrogen mineralization and its prediction in winter wheat-summer maize rotation system].

The mineralization of soil nitrogen in winter wheat-summer maize growth season was studied with field experiment, and its prediction was made by interval leached aerial incubation combined with first-order dynamic model. The results showed that the amount of soil mineralized nitrogen had a large variation among years and crops. The soil nitrogen mineralization was lower in winter wheat growth season than in summer maize growth season, resulted in the yield increment of summer maize being not significant with increasing nitrogen fertilization rate. The amount of soil mineralized nitrogen occupied 31%-60% of the total nitrogen uptake by winter wheat and 62%-108% by summer maize. It was understandable why crop yield (especially summer maize) was not significantly response to applied nitrogen fertilizer. The amount of soil mineralized nitrogen decreased with increasing soil nitrogen supply. The mineralization was positive in normal nitrogen supply range(0-300 kg N.hm-2). The first order dynamic model could only predict the whole trend of mineralization in growth season, but could not reflect its variation in some growth stages. The role of the model was still important in view of the prediction of nitrogen mineralization before sowing.

Crops, Agricultural↗

PubMed1992

Cloning and sequencing of a cDNA encoding 2,3-bisphosphoglycerate-independent phosphoglycerate mutase from maize. Possible relationship to the alkaline phosphatase family.

The primary sequence of maize 2,3-bisphosphoglycerate-independent phosphoglycerate mutase was deduced from cDNAs isolated from maize cDNA libraries by screening with specific antibodies to the cofactor-independent enzyme and from a maize genomic clone. The genomic clone provided the 5'-nucleotide sequence encoding the N-terminal amino acids which could not be obtained from the cDNA. Confirmation that the nucleotide sequence was for the cofactor-independent phosphoglycerate mutase was obtained by sequencing the peptides generated from cyanogen bromide cleavage of the purified protein. This is the first report of the amino acid sequence of a 2,3-bisphosphoglycerate cofactor-independent phosphoglycerate mutase, which consists of 559 amino acids and is twice the molecular size of the mammalian cofactor-dependent enzyme subunit. Analysis of the cofactor-independent phosphoglycerate mutase amino acid sequence revealed no identity with the cofactor-dependent mutase types. Northern blot analysis confirmed this difference since the maize cofactor-independent phosphoglycerate mutase cDNA did not hybridize with mRNA of the cofactor-dependent mutase. The lack of amino acid identity between cofactor-dependent and -independent enzymes is consistent with their different catalytic mechanisms and suggests that both enzymes are unrelated evolutionarily and arose from two independent ancestral genes. However, a constellation of residues which are involved in metal ion binding in various alkaline phosphatases is conserved in the maize cofactor-independent phosphoglycerate mutase, which suggests that the enzyme is a member of the alkaline phosphatase family of enzymes.

Alkaline Phosphatase↗

PubMed2004

[Factors influencing agrobacterium-mediated transformation of maize elite inbred lines].

Using the maize elite inbred lines 9046, Qi319, 414, Mo17 as target genotypes, a highly efficient transformation system was developed based on the study of factors influencing the Agrobacterium-mediated maize transformation. The results showed that the immature embryos of 1.0-2.0 mm in length were optimal transformation explants. Inclusion of acetosyringone (200 micromol/L) and ascorbatic acid (50 mg/L) in both infection medium and co-cultivation medium led to a significantly increase in the transformation efficiency. However, high osmotic treatment on the explants before inoculation didn't improve transformation efficiency. Delaying selection was beneficial to the survival of resistant calli. Using the optimized transformation procedure, 42 PCR-positive transgenic plants were obtained from the 4 elite inbred lines and the frequency of PCR-positive plant ranged from 1.71%-4.09%. The integration of the transgenes into the maize nuclear genome was confirmed by PCR analysis using bar- and gus-specific primers and by Southern blot using gus- specific probe. Most of transgenic plants (71.4%) had one copy of T-DNA insert. The establishment of the transformation system in maize provides an efficient way for transferring useful foreign genes to maize plants.

Blotting, Southern↗

PubMed2002

[The research advancement on genetics of resistance to Exserohilum turcicum in maize].

As the rapid variation and mutation of the races of Exserohilum turcicum (Helminthosporium turcicum), maize varieties lost their resistance to northern corn leaf blight (NCLB) disease caused by new races of E.Turcicum. This brought the disaster in maize production.Up to now 5 races have been found. The maize resistance to E.turcicum can be divided into quantitative and qualitative resistance, the former is associated with 10 chromosomes in maize,and the later includes genes of t1, Ht2, Ht3 and HtN. The race variation of E.turcicum,the original gene resources and genetic characteristics of each Ht monogenic resistance,the chromosome location of t1,Ht2, HtN genes, and the QTL analysis of quantitative resistant genes for E.turcicum in maize were reviewed in this paper.

English Abstract↗

PubMed2005

Nitrogen transformation in maize soil after application of different organic manures.

The nitrogen transformation in maize soil after application of different organic manure was studied. The nitrogen mineralization in surface soil, NO3- -N dynamics and distribution in soil profile, and N2O emission were investigated. Eight treatments were laid out randomizing with three replications in 24 plots: maize plantation without fertilizer (CK1), bare soil without maize plantation and fertilization (CK2), swine manure (S1, S2), poultry manure (P1, P2), and cattle manure (C1, C2). Three manures were applied at two application levels (15 t/hm2 and 30 t/hm2). The results indicated that NH+ -N in surface soil showed the same temporal pattern without much variation among different treatments. But NO3- -N in the same layer exhibited large temporal pattern in all treatments, which was mainly due to its easy eluviations of NO3- -N in soil, its transformation to N2O and the influence of precipitation. The distribution of NO3- -N in the soil profile during maize growing season showed the leaching tendency from surface soil to subsoil, which was different among the treatments. The poultry treatments showed the largest leaching tendency. The study also revealed that the emissions of N2O were affected by the application of organic manures in the order of P2 > S2 > C2 > P1 > S1 > Cl > CK1 > CK2. All these results showed that organic manure applications significantly affect nitrogen transformation and distribution in maize soil. Considering N2O emission and NO3- -N leaching, the management of organic manure in the agriculture needs further studies.

Agriculture↗

PubMed2005

[Reducing the maize amylopectin content through RNA interference manipulation].

To regulate the biosynthesis of maize starch, gene segment of starch branch enzyme (SBE) in maize was cloned and an expression vector of small interference RNA with the fragment of antisense gene + sense gene (pCJSBE2b, Fig.1) was constructed. The expression vector of pCJSBE2b was transformed into maize inbred lines by using pollen-tube pathway. Results of PCR amplification and Southern blotting indicated that the aimed gene with the fragment of antisense gene + sense gene had integrated into receptor maize genome (Fig.4,5) and inherited steadily in the transgenic plants (Table 1). Northern hybridization analysis showed that the aimed gene transcribed normally in the transgenic plants, which resulted in a reduction of endogenous SBE mRNA (Fig.6). The analysis of the activity of starch branching enzyme showed that the enzyme activity decreased obviously in the transgenic plants and maximum decrease was 85% compared to the control plants (Fig.7a). Although the total starch content of transgenic plants showed no change compared to the control plants but the amylose content increased to 50% (Fig.7b) in transgenic plants about 27% higher than receptor maize plants.

1,4-alpha-Glucan Branching Enzyme↗

PubMed2005

The chemical weed control of maize culture in the Danube meadow.

In the world, maize covers about 150 million hectares, following close to rice and wheat. (Balteanu 2000) In Romania, maize culture covers an area of more than 3,500,000 hectares from the overall arable soil, being cultivated in all Romanian districts. Chemical weed control took the greatest extension in the world, at the same time with the synthesis of Atrazine, in 1956, in the laboratories of J.R. Geigy Company, as a super-selective herbicide for the maize culture. This is why many researchers from all continents studied weed control of maize culture, using Atrazine together with other 50 herbicides synthesized until 2004. In the embanked meadow of the Danube, from the 500,000 hectares of arable soil, the maize covers the greatest area. For this reasons, the chemical weed control was granted a great attention by using different herbicides based on Atrazine, Alachlor, Acetochlor, Butilat, Pendimethalin, Dicamba, 2,4-D. At the same time, in the experiments from the Danube Meadow, the authors also studied the efficiency of some combined herbicides: Butizin, Magnific, Guardian Extra is Tazastomp.

Dose-Response Relationship, Drug↗

PubMed2006

[Expression of ZmPIP1 subgroup genes in maize roots under water shortage].

To investigate the role of ZmPIP1-1 and ZmPIP1-2 in water uptake of roots and drought resistance of crops, semi-quantitative PCR was used to examine the expression of ZmPIP1-1 and ZmPIP1-2 in root systems of different maize genotypes under water deficit. These genotypes showed different resistance to water shortage under field conditions. The reference gene to target genes was tubulin. Maize seedlings were grown by hydroponics in a growth chamber. Water deficit was imposed on the seedlings with PEG-6000. The result showed that ZmPIP1-1 was up-regulated under water deficit in root systems of plants of the filial generation 'Hudan 4' and the mother line 'Tiansi', which were resistant to water shortage, but there was no noticeable up-regulation of ZmPIP1-1 in the root systems of the father line '803', which was sensitive to water deprivation. The result also showed that the extent of up-regulation was positively correlated with drought resistance of maize (Fig.3). On the other hand, the expression of ZmPIP1-1 showed different degrees of tendency after different duration of water stress in the root systems of the maize seedlings of different genotypes. The result showed that ZmPIP1-2 was identically expressed in three different species of maize and under different water conditions. The results support the theory that the intercellular water transport contributes to increased water uptake in root systems under water deficit by up-regulating the number of some kinds of aquaporins. The increases amount of transcripts of aquaporins is positively correlated to drought resistance of plant varieties. But not all kinds of number of aquaporins is up-regulated during water shortage, some kinds of aquaporins are identically expressed under water deficit conditions and well watered conditions.

Adaptation, Physiological↗

PubMed1988

Phospholipid transfer protein: full-length cDNA and amino acid sequence in maize. Amino acid sequence homologies between plant phospholipid transfer proteins.

We have determined the primary structure of a phospholipid transfer protein (PLTP) isolated from maize seeds. This protein consists of 93 amino acids and shows internal homology originating in the repetition of (do)decapeptides. By using antibodies against maize PLTP, we have isolated from a cDNA library one positive clone (6B6) which corresponds to the incomplete nucleotide sequence. Another cDNA clone (9C2) was obtained by screening a size-selected library with 6B6. Clone 9C2 (822 base pairs) corresponds to the full-length cDNA of the phospholipid-transfer protein whose mRNA contains 0.8 kilobase. Southern blot analysis shows that the maize genome may contain several PLTP genes. In addition, the deduced amino acid sequence of clone 9C2 reveals the presence of a signal peptide. The significance of this signal peptide (27 amino acids) might be related to the function of the phospholipid-transfer protein. The amino acid sequence of maize PLTP was compared to those isolated from spinach leaves or castor bean seeds which exhibit physicochemical properties close to those of the maize protein. A high homology was observed between the three sequences. Three domains can be distinguished: a highly charged central core (around 40-60), a very hydrophobic N-terminal sequence characteristic of polypeptide-membrane interaction, and a hydrophilic C terminus. A model for plant phospholipid-transfer proteins is proposed in which the phospholipid molecule is embedded within the protein with its polar moiety interacting with the central hydrophilic core of the protein, whereas the N-terminal region plunges within the membrane in the transfer process.

Amino Acid Sequence↗

PubMedDate not supplied

Fast and sensitive screening method for detection of trichothecenes in maize by using protein synthesis inhibition in cultured fibroblasts.

A fast and sensitive bioassay with hamster (BHK-21 C13) fibroblasts for the detection of toxic trichothecenes in maize is described. Cells are exposed to pure toxins or crude maize extracts for 30 min. The mixture is then incubated with [1-14C]-leucine for an additional 60 min and the radioactivity incorporated into the protein of the washed cells is determined. The sensitivity of the assay was in the range 1-10 ng/mL (or 50 ppb in maize) for T-2, HT-2, and diacetoxyscirpenol. At least 1000-fold higher concentrations of non-trichothecene mycotoxins and plant toxins were necessary to cause an inhibition of protein synthesis in the cells. Of 24 maize samples tested, 14 gave a positive response in this assay and the presence of trichothecenes could be confirmed chemically in 11 samples. Therefore, the described bioassay is proposed as a useful screening method for cytotoxic trichothecenes in maize.

Animals↗

PubMed1986

Mycotoxicological investigations on maize and groundnuts from the endemic area of Mseleni joint disease in Kwazulu.

Samples of home-grown maize and groundnuts from the endemic area of Mseleni joint disease (MJD) during four seasons (1980-1983) were examined mycologically. The mycoflora of these dietary staples included Fusarium poae and F. oxysporum, which have been implicated in the aetiology of Kashin-Beck or Urov disease, another osteo-arthrosis endemic in Siberia and China. Two other species of Fusarium, i.e. F. moniliforme and F. equiseti, implicated in syndromes of abnormal bone development in animals, were also present. The predominant fungus associated with maize kernels was F. moniliforme; two other fungi relatively frequently isolated from Mseleni maize, i.e. F. compactum and Lasiodiplodia theobromae, have not previously been reported in maize in southern Africa. The predominant fungi associated with groundnut kernels were Penicillium spp., L. theobromae, Macrophomina phaseolina and F. oxysporum. The incidence of certain fungi, particularly F. compactum, F. oxysporum and L. theobromae, appeared to be higher in dietary staples from households affected by MJD than from non-affected ones. The numbers of samples examined were, however, small and these findings need to be confirmed. Cultures of 120/322 isolates of fungi from Mseleni dietary staples proved toxic to ducklings, the most toxic species being F. compactum, F. moniliforme, F. oxysporum and Phomopsis sp. The characteristic pathological changes of MJD have, however, not been induced in experimental animals with cultures of any of these fungi. A diet containing maize and groundnuts from households affected by MJD also failed to induce the characteristic osteo-arthritic changes of MJD in rats. The dietary staples used in this experiment were, however, collected during seasons of abnormally low rainfall at Mseleni.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1982

Evidence of a thiamine deficiency in sheep fed maize silage.

Two groups of Merino sheep (with or without rumen fistulae) were used to study the effect of feeding maize-silage (compared to hay) on: thiamine concentrations in rumen fluid, tissues and organ; blood transketolase activity; microbial fermentation in the rumen. After sheep were transferred from a hay diet to maize-silage, thiamine concentrations in ruminal fluid fell to about 25% of control values on hay. Thiamine levels greatly decreased in kidney, heart, liver, rumen tissue and large intestine. Blood transketolase and TPP effect significantly decreased (P less than 0.01). Ruminal ammonia nitrogen and total volatile fatty acid (VFA) concentrations were not affected by the two diets. However, both butyric acid and isovaleric acid were significantly higher (P less than 0.001) in rumen fluid of sheep fed maize-silage. No significant differences were detected between diets for ruminal thiaminase activity regardless of the time of sampling. Relationships between butyric fermentation, thiaminase activity in maize-silage diet and a possible role of Clostridium are discussed. It was concluded that there is a marked thiamine deficiency in sheep fed maize-silage; the factors involved need further study.

Animal Feed↗

PubMed2026

Long-term (>7-year) parental consumption of genetically modified maize (Cry1Ab/Cry2Aj and EPSPS) induces no adverse sperm DNA methylation alterations across two generations of cynomolgus monkeys.

This study assessed the long-term safety of genetically modified (GM) maize from a male reproductive perspective, using a non-human primate model. We analyzed the sperm DNA methylation profiles in cynomolgus monkeys fed GM maize, non-GM parental maize, or a conventional diet over two generations (F0/F1). Whole-genome bisulfite sequencing (WGBS) revealed no significant differences in global methylation levels among groups. The identified differentially methylated regions (DMRs) were short, enriched in non-regulatory genomic areas, and did not cluster after treatment. Functional enrichment analysis showed that DMR-associated genes were consistently involved in the same core biological pathways (e.g., mTOR and Wnt signaling) across all dietary comparisons. These findings indicate that GM maize consumption did not induce specific adverse epigenetic alterations in sperm, with the observed changes reflecting common physiological adaptations to dietary variations rather than GM-related effects.

Animals↗

PubMed2026

A GWAS-derived histone H4 variant linked to ear row number reveals functional insights into the maize ZmHistone gene family.

Ear row number (ERN) is a major yield determinant in maize and a key target for breeding of high-yielding varieties. This study utilized a multi-parent population (MPP) of 780 recombinant inbred lines (RILs) derived from seven inbred lines across three environments. Genotyping-by-sequencing (GBS) of the MPP yielded 638,646 high-quality SNPs. Using genome-wide association study (GWAS), we detected 80 significant SNPs including S2-15316355 and S4-224453431, which were consistently detected in all environments and best linear unbiased prediction (BLUP) analysis. A linkage disequilibrium-defined ±20 kb window around these two lead SNPs contained three positional candidate genes: Zm00001eb072840, Zm00001eb072850 and Zm00001eb202890. Zm00001eb072850 (ZmHistone12), a histone H4 variant, was prioritized for hypothesis-driven follow-up because the lead SNP lies within its coding sequence and the gene is expressed in ear-related tissues. Additionally, we identified 91 ZmHistone genes in the maize genome and described their phylogeny, promoter motif and expression patterns. Public transcriptome and qRT-PCR analysis in seven parental lines provide descriptive evidence of Histone variant genes in maize ear development. These results suggest a potential involvement of chromatin-associated regulation of ERN in maize and provide a foundation for future functional validation.

Ear development↗

PubMed2026

Maize Gametophytic factor loci Ga3 through Ga11 modify reproductive barriers.

Gametophytic factor (Ga) barriers are maize (Zea mays ssp. mays) reproductive barriers controlled by molecular incompatibilities between pollen and silks. Twelve distinct Ga loci have been identified in maize populations since the first genetic evidence of a Ga barrier was reported in 1901. Of the twelve, however, only three have been validated by modern molecular, functional and genomic studies: Ga1, Ga2, and Tcb1. The remaining "higher" Ga loci, spanning Ga3 to Ga11, were reported in the historical literature, but their associated phenotypes segregated in unexpected ways or disappeared over subsequent generations. Here we introduce and explore the hypothesis that the higher Ga loci represent modifiers of Ga1, Ga2, and Tcb1 barrier functions. By revisiting the historical literature, we found that barrier phenotypes fall into two phenotypic and functional categories. Phenotypically, the two categories represented healthy pollen with a silk-length effect and unhealthy pollen without a silk-length effect. These phenotypic categories were supported by genomic data; we identified candidate genes in each higher Ga locus by comparing historical linkage mapping data to the corresponding genomic sequence of maize reference line B73. We discovered candidate genes related to two broad pathways: pollen tube growth and RNA-directed DNA methylation. We conclude that the past century of evidence aligns with our hypothesis that maize loci Ga3 through Ga11 modify rather than directly control Ga barriers. This brief investigation provides a starting point for geneticists and evolutionary biologists to explore how strong reproductive barriers are shaped by epistatic interactions.

Epistasis↗