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PubMed2003

[Effect of nitrogen nutrition on endogenous hormone content of maize under soil drought conditions].

It is realized in recent years that roots play an important role in the control of shoot growth and development, not only because they can continuously provide the shoot with water and nutrients, but also because some chemical messengers are produced in roots to response soil drought stress and transported through transpiration stream to shoot where physiological processes are regulated. Extensive studies showed that the decrease of leaf conductance was closely related to the increase of xylem ABA concentration, suggesting that ABA can act as a water stress signal to regulate the physiological response of shoot. Fertilizer plays an important role in increasing crop yield and water use efficiency (WUE) on dry-land farming. It is not clear, however, whether the application of N fertilizer can affect the root's signal intensity in drought stress and thus regulate its stomatal responses. Experiment with 3 water levels (35%, 55% [symbol: see text] 75% +/- 5% of field capacity) and 2 N fertilizer levels (high N and low N) was designed to investigate the effect of soil drought and N nutrition on endogenous hormone concentration (ABA and ZRs) and stomatal conductivity of maize under potted conditions. The results showed that the application of N significantly increased the stomatal conductivity of maize leaf under both drought and watered conditions. Meanwhile, it markedly decreased the ABA concentration in root xylem sap, but increased ABA concentration in leaf of maize under soil drought conditions. The application of N decreased ZRs concentration in root xylem sap as well, which means that ZRs did not play a role in counteractive to ABA under soil drought conditions. The lower ABA concentration in root xylem sap of high N maize rather than the higher ABA concentration in maize leaf accounted for the higher stomatal conductivity of high N maize leaf under soil drought conditions.

Abscisic Acid↗

PubMed2004

[Effect of reduced N application on N utilization and balance in winter wheat-summer maize cropping system].

A field trial on a calcareous soil was carried out at an experimental station of China Agricultural University with the objective of assessing the effect of reduced nitrogen application on N utilization and N balance in a winter wheat-summer maize cropping system. Before this study, the trial has been conducted for one rotation cycle of wheat and maize with four-fixed N rates of 0, 120, 240 and 360 N kg.hm-2 per crop. In this study, each plot was divided into two sub-plots for two N application rates: normal N application(original rate) and reduced N application(reduced rate). The results showed that the grain yields of wheat and maize reached the platform at N rate of 120 kg.hm-2(N120), and then almost kept the same level regardless of the further increase of N rate(N240 and N360). The N uptake by wheat and maize followed the similar tendency like their yield. The grain yield and N uptake of wheat were not significantly declined with the half reduction of original N rate except the treatment N120. However, the same items in maize significantly declined with the further reduction of N fertilizer to zero. The residual NO3-N(main source of mineral N) in reduced N sub-plots was significantly lower in 0-1 m soil layer, but not different in 1-2 m soil layer compared with those receiving original N rate, indicating that 1-2 m soil NO3-N could hardly be utilized by crops. N balance calculation further showed that the N recovery by crops could be largely raised by the reduction of N fertilizer, while the apparent N loss rate decreased in wheat-maize rotation, respectively. Thus, the reduction of fertilizer N under high N rate can significantly increase N use efficiency and reduce NO3-N accumulation and apparent N loss.

Crops, Agricultural↗

PubMed2004

Pathogenic effects of Salmonella enterica subspecies enterica serovar Typhimurium on sprouting and growth of maize.

The study was undertaken to understand effects and survival of S. enterica subspecies enterica serovar Typhimurium (S. Typhimurium), a zoonotic serovar, on maize seed germination and plant growth. All the four strains of S. enterica subspecies enterica serovar Typhimurium significantly reduced germination of maize seeds in sprouting plates as well as in soil. About > or =2.7x10(3) Salmonella cfu ml(-1) of soaking water, while > or =2.7x10(7) Salmonella cfu g(-1) soil were required to significantly inhibit germination of maize. Similar inhibition of germination could be observed using > or = 16 mg of bacteria free Salmonella cell lysate (CL) protein per g of soil or > or =0.5 mg of CL protein per ml of soaking water in sprouting plates. At the constant dose of 3.6x10(7) to 3.8x10(7) Salmonella cfu or 5 mg cell lysate protein ml(-1) of soaking water, four strains of Salmonella significantly reduced germination, however difference between strains was insignificant. After germination too, maize growth was affected both by Salmonella organism and CL with little strain-to-strain variation. All Salmonella persisted in growing plants from 15 to 35 days of plant age and up to 190 days in soil. Maize plants once grown for a week in sterile soil were resistant to invasion of S. enterica subspecies enterica serovar Typhimurium in their leaves even in doses as high as 7.6x10(9) cfu g(-1) of soil. Salmonella persisted better and longer in plants grown from contaminated seed sown in loam soil, but rarely in plants grew in sandy soil. All maize plants had Salmonella in their stumps even after 35 days of sowing irrespective of kind of soil, primary source of infection (soil or seed) and type of S. enterica subspecies enterica serovar Typhimurium strain. The study revealed that Salmonella is not only zoonotic but a phytopathogen also.

Germination↗

PubMed1997

Comparison of maize and alfalfa silages on milk production, milk composition and blood components of dairy cows.

Twenty multiparous Friesian cows, 60 to 100 days postpartum, were allotted to two groups of 10 cows according to calving date, lactation number, and daily milk production and were assigned randomly to one of two diets in a crossover design experiment. The control diet (maize diet) was 55% maize silage (dry basis), 20% soybean meal, 22% ground maize, and 3% mineral and vitamin mix. The treatment diet (alfalfa diet) was 55% alfalfa silage, 10% soybean meal, 32% ground maize, and 3% mineral and vitamin mix. The two diets contained similar quantities of crude protein and metabolizable energy. The diets were offered individually as total mixed rations in two equal portions at 09:00 and 20:00 h in amounts to achieve ad libitum intake. The two groups of cows were allowed exercise in an open lot without shade from 11:00 to 16:30 h and 22:00 to 05:30 h. The cows were milked daily at 06:00 and 17:00 h. The dry matter, metabolizable energy and crude protein intakes, milk production, and milk fat, protein, lactose, total solids and solids not fat contents, as well as milk fat and protein yields and body condition score, were not significantly affected when maize silage was given to lactating cows, compared with that of cows given alfalfa silage. No differences were observed in blood serum concentrations of glucose, total protein, albumin, urea, triglycerides, cholesterol, Na, K, Ca, P and Mg between maize and alfalfa silages.

Animal Feed↗

PubMed2026

Recurrent and niche-specific functional bacteriome of maize hybrid revealed by integrated metabarcoding and culturomics.

The plant microbiome plays a pivotal role in plant survival in natural habitats by facilitating nutrient acquisition, stress adaptation, and disease suppression, while also offering opportunities to enhance crop productivity and climate resilience. However, the distribution of persistent and culturable bacteriome across maize-associated niches and their functional potential remain poorly resolved. This study integrated metagenomic next-generation sequencing (mNGS-based metabarcoding) and culturomics to characterise the maize-associated bacteriome of bulk soil, rhizoplane, phylloplane, and cob of the maize hybrid PHM-1 under contrasting cropping and tillage systems, and to identify recurrent and agriculturally promising bacteriome components. The bacteriome exhibited pronounced niche-specific structuring, whereas overall bacterial community composition did not differ significantly across cropping and tillage treatments (ANOSIM, R = 0.038, p = 0.306). Proteobacteria predominated in the culturable bacteriome (69-84%; mean, 76.2%) but accounted for only 1% of the total bacteriome, whereas Patescibacteria and Firmicutes were relatively enriched. Niche-specific dominance was evident, with Pantoea accounting for 40.79% of the total and 56.27% of the culturable phylloplane bacteriome under cereal monocropping, while Serratia represented 31.59% and 59.40% of the total and culturable cob bacteriomes, respectively. Across niches, mNGS captured substantially greater bacteriome diversity, particularly uncultured and unidentified taxa in soil-associated compartments, whereas culturomics recovered a narrower but functionally accessible fraction. Culturomics yielded 99 isolates representing 32 species across 12 genera, including six genera shared with the mNGS-derived recurrent bacteriome: Bacillus, Enterobacter, Pantoea, Pseudomonas, Serratia, and Stenotrophomonas. Functional screening identified strong biocontrol and plant-beneficial traits among core-associated isolates. Pseudomonas oryzihabitans ZM-DL-PA10 inhibited Rhizoctonia solani, Macrophomina phaseolina, and Bipolaris maydis by up to 40.6%, 43.9%, and 45.2%, respectively, through secreted and volatile metabolites; exhibited P, K, and Zn solubilisation; and produced IAA and siderophores. It also recorded the lowest B. maydis disease index (ADI) of 1.00. Pantoea ananatis ZM-BH-EA4 showed 52.4% and 68.5% inhibition of R. solani and B. maydis, respectively, through volatile metabolites. Collectively, the integration of mNGS and culturomics revealed a strongly compartmentalised maize bacteriome and identified recurrent, culturable, and functionally promising bacterial taxa, providing a targeted resource for microbiome-based crop protection and climate-resilient maize production.

Zea mays↗

PubMed2026

Pan-genome characterization of the maize 4CL gene family and its dynamic responses to abiotic stress.

1.Pan-genome analysis across 26 maize inbred lines identified 13 Zm4CL genes (nine core and four near-core) classified into three evolutionary clades.2.Structural variations (SVs) are significantly associated with the expression and altered conserved protein domains of key Zm4CL genes.3.Zm4CL genes exhibit distinct tissue-specific expression patterns and dynamic enzymatic and transcriptional responses to stresses, particularly cold and drought.4-Coumarate:CoA ligase (4CL) is a key enzyme in the phenylpropanoid pathway and plays important roles in plant growth, development, and responses to environmental stresses. However, a comprehensive pan-genome analysis of the 4CL gene family in maize is still lacking. In this study, 13 Zm4CL genes were identified from a maize pan-genome comprising 26 diverse inbred lines, including nine core genes and four near-core genes. Phylogenetic analysis classified these genes into three evolutionary clades, while Ka/Ks analysis indicated that most members have been maintained under purifying selection, although several genes exhibited greater evolutionary divergence and relatively relaxed evolutionary constraints. Structural variation (SV) analysis revealed significant associations between SVs and the expression of Zm4CL2 and Zm4CL3, while sequence comparisons suggested that SVs were also associated with alterations in conserved protein domains in some genotypes. Transcriptome analyses revealed distinct tissue-specific expression patterns and diverse transcriptional responses to abiotic and biotic stresses. Enzyme activity assays showed that cold stress significantly increased 4CL activity at 12 h, whereas heat, salt, and alkali stresses caused an initial decrease followed by recovery, while drought had no significant effect. Time-course RT-qPCR further validated dynamic expression changes of representative Zm4CL genes under cold and drought stresses. Overall, this study provides a comprehensive pan-genome framework for understanding the evolutionary conservation, regulatory diversification, and stress-responsive characteristics of the maize Zm4CL gene family, providing valuable resources for future functional studies and the genetic improvement of stress tolerance in maize.

Zea mays↗

PubMed2026

Integrating GWAS and Transcriptome Analysis Identifies Candidate Genes for Kernel Starch Quality Traits in Maize.

Maize (Zea mays L.) starch quality is a complex trait with significant implications for grain processing and industrial applications. However, the genetic basis underlying starch quality, particularly for gelatinization and thermodynamic properties, remains poorly understood. In this study, we evaluated 12 starch quality traits, including seven gelatinization characteristics, four thermodynamic traits, and kernel starch content (KSC) in a diverse panel of 335 maize inbred lines. Considerable phenotypic variation was observed for all traits. A total of 228 quantitative trait loci (QTLs) were significantly associated with 12 starch quality traits through genome-wide association studies (GWAS). By integrating a dynamic transcriptome analysis of two maize inbred lines with contrasting starch quality, we identified 60 candidate genes. One gene, waxy1, encoding a starch synthase, was found to be associated with enthalpy of gelatinization (ΔHgel) and pasting temperature (Ptemp). Six variants in waxy1 contributed to natural variation in ΔHgel and Ptemp, and a cost-effective InDel and two PARMS-based molecular markers were developed and validated in 144 maize inbred lines, enabling efficient marker-assisted selection. Our findings provide key genes and molecular markers for high-quality maize breeding with improved starch properties.

Zea mays↗

PubMed2026

QTLs associated with phenolic acid accumulation and antioxidant activity in tropical maize.

Maize represents a significant source of phytochemicals, with phenolic acids standing out as one of the most extensively studied functional compound families. These bioactive molecules have gained attention for their potent antioxidant properties and potential contributions to human health improvement. To evaluate the segregation of phenolic compounds in maize and its genetic basis, this study was conducted to identify quantitative trait loci (QTLs) associated with major phenolic compounds and their antioxidant capacity. The mapping population comprised 100 recombinant inbred lines (RILs) derived from the cross between P84 and Kilima. Twelve traits were analyzed: free and cell wall-bound antioxidant capacity, total phenolic content, and contents of p-coumaric acid, ferulic acid, three isomers of di-ferulic acid, and three isomers of tri-ferulic acid. The RILs exhibited substantial diversity in phenolic compound profiles. In total, 19 QTLs were identified for nine traits, with the number of associated regions ranging from 1 to 5 and explaining between 2.95% and 37.48% of the phenotypic variation. This research provides substantial evidence for the co-localization of major QTLs for principal phenolic acids in maize with genomic regions harboring genes putatively related to their biosynthesis and biotic resistance. This is the first study to report QTLs associated with triferulic acids in maize. The identified regions co-localizing with biotic stress resistance genes represent targets for marker-assisted selection toward the improvement of phenolic acid accumulation in maize breeding programs.

QTLs↗

PubMed2002

Influence of gamma-irradiation and maize lipids on the production of aflatoxin B1 by Aspergillus flavus.

The effect of gamma-irradiation and maize lipids on aflatoxin B1 production by Aspergillus flavus artificially inoculated into sterilized maize at reduced water activity (aw 0.84) was investigated. By increasing the irradiation doses the total viable population of A. flavus decreased and the fungus was completely inhibited at 3.0 kGy. The amounts of aflatoxin B1 were enhanced at irradiation dose levels 1.0 and 1.5 kGy in both full-fat maize (FM) and defatted maize (DM) media and no aflatoxin B1 production at 3.0 kGy gamma-irradiation over 45 days of storage was observed. The level in free lipids of FM decreased gradually, whereas free fatty acid values and fungal lipase activity increased markedly by increasing the storage periods. The free fatty acid values decreased by increasing the irradiation dose levels and there was a significant enhancement of fungal lipase activity at doses of 1.0 and 1.50 kGy. The ability of A. flavus to grow at aw 0.84 and produce aflatoxin B1 is related to the lipid composition of maize. The enhancement of aflatoxin B1 at low doses was correlated to the enhancement of fungal lipase activity.

Aflatoxin B1↗

PubMed2005

Reduced representation sequencing: a success in maize and a promise for other plant genomes.

Plant, and particularly cereal genomes, are challenging to sequence due to their large size and high repetitive DNA content. Gene-enrichment strategies are alternative or complementary approaches to complete genome sequencing that yield, rapidly and inexpensively, useful sequence data from large and complex genomes. The maize genome is large (2.7 Gbp) and contains large amounts of conserved repetitive elements. Furthermore, the high allelic diversity found between maize inbred lines may necessitate sequencing several inbred lines in order to recover the maize "gene pool". Two gene-enrichment approaches, methylation filtration (MF) and high C(o)t (HC) sequencing have been tested in maize and their ability to sample the gene space has been examined. Combined with other genomic sequencing strategies, gene-enriched genomic sequencing is a practical way to examine the maize gene pool, to order and orient the genic sequences on the genome, and to enable investigation of gene content of other complex plant genomes.

Alleles↗

PubMed2004

Distribution and metabolism of D/L-, L- and D-glufosinate in transgenic, glufosinate-tolerant crops of maize (Zea mays L ssp mays) and oilseed rape (Brassica napus L var napus).

The aim of the present study was to determine whether post-emergence application of glufosinate to transgenic crops could lead to an increase in residues or to the formation of new, hitherto unknown metabolites. Transgenic oilseed rape and maize plants were treated separately with L-glufosinate, D-glufosinate or the racemic mixture. Whereas about 90% of the applied D-glufosinate was washed off by rain and only 5-6% was metabolised, 13-35% of the applied L-glufosinate remained in the form of metabolites and unchanged herbicide in both transgenic maize and oilseed rape. The main metabolite was N-acetyl-L-glufosinate with total residues of 91% in oilseed rape and 67% in maize, together with small amounts, of 5% in oilseed rape and 28% in maize, of different methylphosphinyl fatty acids. These metabolites were probably formed from L-glufosinate by deamination and subsequent decarboxylation. The residues were distributed in all fractions of the plants, with the highest contents in treated leaves and the lowest in the grains (0.07-0.3% in maize and 0.4-0.6% in oilseed rape). There was no indication of an accumulation of total residues or of residue levels above the official tolerances for glufosinate.

Acetylation↗

PubMed1993

Partial purification and characterization of phosphoenolpyruvate carboxylase protein-serine kinase from illuminated maize leaves.

Following in situ renaturation and assay of protein kinase activity after denaturing electrophoresis of relatively impure samples of maize phosphoenolpyruvate carboxylase (PEPC) kinase, a approximately 30-kDa polypeptide was implicated as the best candidate for the PEPC kinase catalytic subunit. This kinase's apparent native molecular weight was estimated at 28,000 by gel filtration on a calibrated Superose 12 column (HR 10/30), suggesting that the isolated PEPC kinase is monomeric. This protein-serine kinase was partially purified about 4000-fold from illuminated maize leaves by ammonium sulfate precipitation and sequential chromatography on Ultrogel AcA 54, hydroxylapatite, blue dextran-agarose, and an analytical AcA 54 column. Analysis by denaturing electrophoresis revealed that a 30-kDa polypeptide copurified with PEPC kinase activity during the final step. This highly purified kinase had an apparent Km (PEPC subunit) of 2.5 microM and a Km (total ATP) of 40 microM at pH 8.0, its pH optimum. Upon in vitro phosphorylation of darkform (dephospho) C4 PEPC at Ser-15 (maize PEPC) or Ser-8 (sorghum), the malate sensitivity of the target enzyme decreased significantly. The maize PEPC kinase activity was markedly inhibited by L-malate, a negative allosteric effector of its protein substrate, in a concentration- and pH-dependent manner. Comparative phosphorylation studies with the catalytic subunit of mammalian cAMP-dependent protein kinase and casein revealed that a significant part of the malate inhibition of PEPC kinase activity in vitro was due to this effector's interaction with PEPC. The activity of both the highly purified PEPC kinase and a less pure sample prepared rapidly in the presence of various protease inhibitors was insensitive to Ca2+ chelation or addition. It is concluded that the approximately 30-kDa maize PEPC kinase is a low abundance, Ca(2+)-independent protein-serine kinase that activates its target enzyme by the exclusive phosphorylation of the regulatory serine residue near the N terminus and the resulting decrease in feedback inhibition by L-malate.

Calcium↗

PubMed2001

Structural basis of non-specific lipid binding in maize lipid-transfer protein complexes revealed by high-resolution X-ray crystallography.

Non-specific lipid-transfer proteins (nsLTPs) are involved in the movement of phospholipids, glycolipids, fatty acids, and steroids between membranes. Several structures of plant nsLTPs have been determined both by X-ray crystallography and nuclear magnetic resonance. However, the detailed structural basis of the non-specific binding of hydrophobic ligands by nsLTPs is still poorly understood. In order to gain a better understanding of the structural basis of the non-specific binding of hydrophobic ligands by nsLTPs and to investigate the plasticity of the fatty acid binding cavity in nsLTPs, seven high-resolution (between 1.3 A and 1.9 A) crystal structures have been determined. These depict the nsLTP from maize seedlings in complex with an array of fatty acids.A detailed comparison of the structures of maize nsLTP in complex with various ligands reveals a new binding mode in an nsLTP-oleate complex which has not been seen before. Furthermore, in the caprate complex, the ligand binds to the protein cavity in two orientations with equal occupancy. The volume of the hydrophobic cavity in the nsLTP from maize shows some variation depending on the size of the bound ligands. The structural plasticity of the ligand binding cavity and the predominant involvement of non-specific van der Waals interactions with the hydrophobic tail of the ligands provide a structural explanation for the non-specificity of maize nsLTP. The hydrophobic cavity accommodates various ligands from C10 to C18. The C18:1 ricinoleate with its hydroxyl group hydrogen bonding to Ala68 possibly mimics cutin monomer binding which is of biological importance. Some of the myristate binding sites in human serum albumin resemble the maize nsLTP, implying the importance of a helical bundle in accommodating the non-specific binding of fatty acids.

Binding Sites↗

PubMed1999

Light regulation of nitrate reductase gene expression in maize involves a G-protein.

This paper reports three lines of evidence to demonstrate the presence of heterotrimeric G-proteins in maize and their involvement in the regulation of nitrate reductase gene expression by light: (1) Southern blot analysis of maize genomic DNA using a human Ha-ras cDNA probe revealed specific bands indicating the presence of G-protein (alpha subunit) gene(s) in maize. Northern blot analysis of maize total RNA using the same probe revealed that the putative Galpha gene(s) is transcriptionally active. (2) Western blots containing purified plasma membrane proteins from maize leaves showed specific binding of gamma [35S]-labeled GTP in a red light-dependent manner, indicating the involvement of G-proteins in mediating the light signal. The size of the putative Galpha gene product (approximately 45 kDa) indicates that it may be a heterotrimeric G-protein. (3) Cholera toxin mimicked the effect of red light to enhance the transcript levels of nitrate reductase (NR), indicating that G-proteins may mediate light regulation of NR gene expression.

Blotting, Northern↗

PubMed1996

Susceptibilities of Different Test Systems from Maize (Zea mays), Poa annua, and Festuca rubra to Herbicides That Inhibit the Enzyme Acetyl-Coenzyme A Carboxylase

The susceptibilities of maize (Zea mays cv. Champ) and two graminicide-resistant grass species, Poa annua (annual meadow grass) and Festuca rubra (red fescue), to two aryloxyphenoxypropionates (quizalofop and fluazifop) and a cyclohexanedione (sethoxydim) graminicide were evaluated in leaf blades and isolated chloroplasts, and by assaying acetyl-coenzyme A carboxylase (ACCase) in desalted leaf homogenates. The graminicide resistance of P. annua and F. rubra appeared to be at the level of ACCase. Festuca rubra ACCase was highly insensitive and P. annua ACCase was partially insensitive to the graminicides that were tested. Fatty acid synthesis in isolated maize chloroplasts was more susceptible to inhibition than was ACCase activity from whole leaves. There was a smaller difference in graminicide sensitivity between these two test systems in P. annua. The developmental pattern of ACCase specific activity and its inhibition by quizalofop was measured in maize and P. annua leaf blades. There was an age-dependent increase in the sensitivity of maize leaf ACCase activity to inhibition by quizalofop. Together with the greater susceptibility of chloroplasts compared with leaf homogenates this could imply that a graminicide-insensitive (extrachloroplastic) ACCase isoform is less highly expressed in older leaves. Poa annua ACCase did not significantly alter in sensitivity as leaves aged, consistent with the smaller difference in the level of inhibition between chloroplasts and leaf homogenates in this species. A small pyruvate carboxylase activity was detected in maize leaves after 9 days. By 38 days, when leaves were senescing, pyruvate carboxylase activity predominated over ACCase.

Journal Article↗

PubMed1996

Light-dependent developmental control of rbcS gene expression in epidermal cells of maize leaves.

Regulatory elements of the maize rbcS-m3 gene (a member of the family of genes encoding the small subunit of ribulose bisphosphate carboxylase) that are sufficient for expression of the beta-glucuronidase (gusA) gene in photosynthetic tissue lead to relatively weak expression of the reporter gene in epidermal cells of green maize leaves when delivered by ballistic gene transfer methods. However, epidermal cells of white, immature segments of maize leaf bases express the same reporter gene strongly. Morphologically, these epidermal cells look undifferentiated and are uniform in size and shape. When cultured for seven days on Murashige-Skoog medium [18], exised leaf base segments expand two-to threefold, and epidermal and guard cells differentiate and mature, regardless of whether or not the tissue is illuminated. Epidermal cells that differentiate in darkness continue to have the capacity to express the rbcS-m3::gusA reporter gene strongly. However, if the leaf base segments are illuminated after four to five days of expansion in darkness, but not before, these more mature epidermal cells are largely unable to express the same gene. That is, they acquire the characteristics of epidermal cells of green maize leaves with regard to expressing the rbcS-m3 reporter gene after undergoing a developmental program (in light or darkness) in vitro and after being exposed to light. White light but not red is effective. Suppression of expression in maize epidermal cells requires different rbcS-m3 sequences than in mesophyll cells [31].

Chloroplasts↗

PubMed1995

Intron-dependent transient expression of the maize GapA1 gene.

Transient expression experiments show that the maize GapA1 promoter exhibits a requirement for sequences contained within intron 1 and surrounding exon border regions for expression in maize Black Mexican Sweet cells. Maize GapA1-promoter constructs lacking intron 1 are inactive. Intron 1 and its exon border sequences, when reintroduced into constructs lacking introns, restore gene activity whereas intron 2 and its exon borders to not. The minimal promoter so defined encompasses roughly 250 bp upstream of the in vivo transcription start and appears also to include intron 1. An octameric sequence was identified in intron 1 of maize GapA1 which is similar to sequence motifs found in other maize introns known to increase transient expression. Partial restoration of gene expression in GapA1 constructs lacking intron 1 was achieved through insertion of the identified octameric sequence.

Base Sequence↗

PubMed1995

The involvement of Opaque 2 on beta-prolamin gene regulation in maize and Coix suggests a more general role for this transcriptional activator.

The maize opaque 2 (o2) mutation is known to have numerous pleiotropic effects. Some polypeptides have their expression depressed while others are enhanced. The best characterized effects of the o2 mutation are those exerted on endosperm genes encoding the storage protein class of the 22 kDa alpha-zeins and the ribosome inactivating protein b-32. The Opaque 2 (O2) locus encodes a basic domain-leucine zipper DNA-binding factor, O2, which transcriptionally regulates these genes. In the maize-related grass Coix lacryma-jobi, an O2-homologous protein regulates the 25 kDa alpha-coixin family. We show in this paper that O2 transcriptionally regulates the structurally and developmentally different class of the beta-prolamins. A new O2-binding box was identified in beta-prolamin genes from maize and Coix that, together with the boxes previously identified in other endosperm expressed genes, forms a curious collection of O2 cis elements. This may have regulatory implications on the role of O2 in the mechanism that controls coordinated gene expression in the developing endosperm. Considering that the O2 locus controls at least three distinct classes of genes in maize endosperm, we propose that the O2 protein may play a more general role in maize endosperm development than previously conceived.

Base Sequence↗