A mitogen-activated protein kinase of the corn leaf pathogen Cochliobolus heterostrophus is involved in conidiation, appressorium formation, and pathogenicity: Diverse roles for mitogen-activated protein kinase homologs in foliar pathogens

Fungal pathogens perceive and respond to molecules from the plant, triggering pathogenic development. Transduction of these signals may use heterotrimeric G proteins, and it is thought that protein phosphorylation cascades are also important. We have isolated a mitogen-activated protein kinase homolog from the corn pathogen Cochliobolus heterostrophus to test its role as a component of the transduction pathways. The new gene, CHK1, has a deduced amino acid sequence 90% identical to Pmk1 of the rice blast fungus Magnaporthe grisea and 59% identical to Fus3 of Saccharomyces cerevisiae. A series of chk1 deletion mutants has poorly developed aerial hyphae, autolysis, and no conidia. No pseudothecia are formed when a cross between two Δchk1 mutants is attempted. The ability of Δchk1 mutants to infect corn plants is reduced severely. The growth pattern of hyphae on a glass surface is strikingly altered from that of the wild type, forming coils or loops, but no appressoria. This set of phenotypes overlaps only partially with that of pmk1 mutants, the homologous gene of the rice blast fungus. In particular, sexual and asexual sporulation both require Chk1 function in Cochliobolus heterostrophus, in contrast to Pmk1, but perhaps more similar to yeast, where Fus3 transmits the mating signal. Chk1 is required for efficient colonization of leaf tissue, which can be compared with filamentous invasive growth of yeast, modulated through another closely related mitogen-activated protein kinase, Kss1. Ubiquitous signaling elements thus are used in diverse ways in different plant pathogens, perhaps the result of coevolution of the transducers and their targets.

Potentials of the National Corn Genome Initiative

The present paper summarizes future needs in information and tools, technology, infrastructure, training, funding, and bioinformatics, to provide the genomic knowledge and tools for breeding and biotechnological goals in maize. The National Corn Genome Initiative (NCGA) has developed through actions taken by the National Corn Growers Association (NCGA) and participation in a planning process by institutions, companies, and organizations. At the web address for the NCGI, http://www.inverizon.com/ncgi, are detailed analyses of goals and costs, impact and value, and strategy and approaches. The NCGI has also produced an informative and perceptive video suitable for public groups or schools, about agricultural contributions to life and the place of maize in these contributions. High potential can be expected, from cross-application of knowledge obtained in maize and other cereals. Development of information and tools for all crops, whether monocots or dicots, will be gained through an initiative, and each crop will be positioned to advance with cost-effective parallels, especially for expressed sequences, markers, and physical mapping.

Adaptation of Active Proton Pumping and Plasmalemma ATPase Activity of Corn Roots to Low Root Medium pH1

Corn (Zea mays L.) root adaptation to pH 3.5 in comparison with pH 6.0 (control) was investigated in long-term nutrient solution experiments. When pH was gradually reduced, comparable root growth was observed irrespective of whether the pH was 3.5 or 6.0. After low-pH adaptation, H+ release of corn roots in vivo at pH 5.6 was about 3 times higher than that of control. Plasmalemma of corn roots was isolated for investigation in vitro. At optimum assay pH, in comparison with control, the following increases of the various parameters were caused by low-pH treatment: (a) hydrolytic ATPase activity, (b) maximum initial velocity and Michaelis constant (c) activation energy of H+-ATPase, (d) H+-pumping activity, (e) H+ permeability of plasmalemma, and (f) pH gradient across the membranes of plasmalemma vesicles. In addition, vanadate sensitivity remained unchanged. It is concluded that plasmalemma H+-ATPase contributes significantly to the adaptation of corn roots to low pH. A restricted net H+ release at low pH in vivo may be attributed to the steeper pH gradient and enhanced H+ permeability of plasmalemma but not to deactivation of H+-ATPase. Possible mechanisms responsible for adaptation of plasmalemma H+-ATPase to low solution pH during plant cultivation are discussed.

Quantitative trait loci and metabolic pathways: genetic control of the concentration of maysin, a corn earworm resistance factor, in maize silks.

Interpretation of quantitative trait locus (QTL) studies of agronomic traits is limited by lack of knowledge of biochemical pathways leading to trait expression. To more fully elucidate the biological significance of detected QTL, we chose a trait that is the product of a well-characterized pathway, namely the concentration of maysin, a C-glycosyl flavone, in silks of maize, Zea mays L. Maysin is a host-plant resistance factor against the corn earworm, Helicoverpa zea (Boddie). We determined silk maysin concentrations and restriction fragment length polymorphism genotypes at flavonoid pathway loci or linked markers for 285 F2 plants derived from the cross of lines GT114 and GT119. Single-factor analysis of variance indicated that the p1 region on chromosome 1 accounted for 58.0% of the phenotypic variance and showed additive gene action. The p1 locus is a transcription activator for portions of the flavonoid pathway. A second QTL, represented by marker umc 105a near the brown pericarp1 locus on chromosome 9, accounted for 10.8% of the variance. Gene action of this region was dominant for low maysin, but was only expressed in the presence of a functional p1 allele. The model explaining the greatest proportion of phenotypic variance (75.9%) included p1, umc105a, umc166b (chromosome 1), r1 (chromosome 10), and two epistatic interaction terms, p1 x umc105a and p1 x r1. Our results provide evidence that regulatory loci have a central role and that there is a complex interplay among different branches of the flavonoid pathway in the expression of this trait.

The loss of female sex pheromone after mating in the corn earworm moth Helicoverpa zea: identification of a male pheromonostatic peptide.

Female moths often become depleted of sex pheromone after mating as the various components of virgin behavior are switched off. In examining a potential male contribution to these events in the corn earworm moth Helicoverpa zea, we have characterized a basic polypeptide from the tissues producing (accessory glands) and storing (duplex) the seminal fluids. The peptide evokes the depletion of sex pheromone when injected into virgin females. This pheromonostatic peptide (PSP) is 57 amino acids long and contains a single disulfide bridge. It is blocked at the N terminus with pyroglutamate and at the C terminus by amidation. As little as 23 ng of peptide evokes the near-complete depletion of pheromone in decapitated (neck-ligated) females that had been injected with pheromone biosynthesis-activating neuropeptide. Activity is approximately 15-fold less in intact virgins, showing that the head limits the expression of activity in these injected females. Females mated to surgically impaired males, capable of producing a spermatophore but not transferring spermatozoa or seminal fluids, are depleted of pheromone by injected peptide. Females whose abdominal nerve cords have been severed are not depleted of pheromone after mating. Thus, neural signals either descending or ascending via the nerve cord are required for the depletion of pheromone after mating. PSP, from the seminal fluids, may participate in this process by direct or indirect action on the glandular tissue; if so, it represents an unusual mechanism in insects for the regulation by seminal fluids of postmating reproductive behavior.

Corn Liberalization in Mexico: The Effects of Neoliberal Policies on Campesino Food Security

Mexico has a long history of structuralized violence against its most vulnerable socioeconomic strata, the peasantry, also referred to as Campesinos. From the Spanish invasion, to the contemporary neoliberal development project, corn production has been intimately associated with disparate power relations both within Mexican society, and without, particularly in relations with the United States. This study sheds light on the incongruities of modernism implicit within neoliberal policy instruments such as Structural Adjustment Programs (SAP) and free trade agreements. It will demonstrate that while such policies benefit some, they principally exacerbate existing power disparities via disarticulated trade economics, subordinating rather than liberating Mexico's most vulnerable citizenry.

Corn stover thermal decomposition in pyrolytic and oxidant atmosphere

The pyrolysis and combustion of corn stover were studied by dynamic thermogravimetry and derivate thermogravimetry (TG-DTG) at heating rates of 5, 10, 20 and 50 K min−1 at atmospheric pressure. For the simulation of pyrolysis and combustion processes a kinetic model based on the distribution of activation energies was used, with three pools of reactants (three pseudocomponents) because of the complexity of the biomass samples of agricultural origin. The experimental thermogravimetric data of pyrolysis and combustion processes were simultaneously fitted to determine a single set of kinetic parameters able to describe both processes at the different heating rates. The model proposed achieves a good correlation between the experimental and calculated curves, with an error of less than 4% for fitting four heating rates simultaneously. The experimental results and kinetic parameters may provide useful data for the design of thermo decomposition processing system using corn stover as feedstock. On the other hand, analysis of the main compounds in the evolved gas is given by means of a microcromatograph.

Indian corn / by James B. McNair, Asst. Curator of Economic Botany.

no.14(1930)

Fire behaviour of lightweight concrete units based on corn cob aggregate

Recent research works have concluded that corn cob may have interesting material properties, in particular, lightness, and thermal and sound insulation abilities. In this research work, corn cob is proposed as an alternative sustainable aggregate for lightweight concrete masonry unit (CMU) manufacturing. The corn cob requires to be granulated previously in order to obtain adequate particle size grade. Subsequently, the particles are wrapped in a cement paste with the purpose of reducing their water abortion and adherent capacities. CMU are current applied in the building of partition walls. The main goal of this research work consists on studying the fire behaviour of partition walls built with CMU of processed corn cob granulate (CMU-PCC).

Soy & corn production on small farms /

"Addendum to the Project Paper, 'Corn and soy production on small farms' ... prepared in response to STATE 160059, 'DAEC review soy and corn grant pp'."

Biological treatment of wastes from corn wet milling industry /

Grant no. 12060 DPE.

Alternatives for reducing insecticides on cotton and corn : economic and environmental impact /

"Grant no. R802518-02."

Composition and digestibility of corn ensilage, cowpea ensilage, soja bean ensilage, and corn-fodder /

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Insect injuries to the seed and root of Indian corn /

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