50 research outputs found

    MOLECULAR TECHNOLOGY FOR DEVELOPING DURABLE RESISTANCE TO THE SUGAR BEET ROOT MAGGOT (TETANOPS MYOPAEFORMIS)

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    Abstract Sugar beet root maggot (SBRM), Tetanops myopaeformis von Röder, is a major economic insect pest of sugar beet in North America. While several moderately resistant breeding lines have recently been registered, they do not offer complete control. A significant amount of knowledge about how plants protect themselves against insect invasion is being provided by advances being made in bioinformatics and functional genomics, however, complementary molecular studies on insect adaptive mechanisms used to overcome host resistance and develop tolerance to many insecticides are lacking. This study was initiated to establish a transcriptomic profile of SBRM genes and to identify physiologically valuable genes that can serve as targets for bio-insecticides and RNA interference mediated pest control. PCRselect suppressive subtractive hybridization (SSH) was used to produce an annotated SBRM EST dataset as a reference point for genes whose expression is modulated by interactions with resistant or susceptible sugar beet roots. This data will provide new insights into the molecular response elicited by SBRM in interactions with sugar beet roots and will advance the development of novel approaches for more effective SBRM control. Introduction Little information is available on how insects evolve adaptive mechanisms to overcome host resistance and develop tolerance to many insecticides used for their control. To gain a better understanding of insect biochemistry and molecular biology, this study was initiated to establish a transcriptomic profile of the sugar beet root maggot (SBRM, Tetanops myopaeformis) and to identify physiologically valuable genes that could serve as targets for development of pest control strategies. PCR-select suppressive subtractive hybridization (SSH) was used to generate cDNA libraries of SBRM genes that were specifically up-or down-regulated when the insect was feeding on resistant or susceptible sugar beet root

    Genetic architecture of common bunt resistance in winter wheat using genome-wide association study

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    Background: Common bunt (caused by Tilletia caries and T. foetida) has been considered as a major disease in wheat (Triticum aestivum) following rust (Puccinia spp.) in the Near East and is economically important in the Great Plains, USA. Despite the fact that it can be easily controlled using seed treatment with fungicides, fungicides often cannot or may not be used in organic and low-input fields. Planting common bunt resistant genotypes is an alternative. Results: To identify resistance genes for Nebraska common bunt race, the global set of differential lines were inoculated. Nine differential lines carrying nine different genes had 0% infected heads and seemed to be resistant to Nebraska race. To understand the genetic basis of the resistance in Nebraska winter wheat, a set of 330 genotypes were inoculated and evaluated under field conditions in two locations. Out of the 330 genotypes, 62 genotypes had different degrees of resistance. Moreover, plant height, chlorophyll content and days to heading were scored in both locations. Using genome-wide association study, 123 SNPs located on fourteen chromosomes were identified to be associated with the resistance. Different degrees of linkage disequilibrium was found among the significant SNPs and they explained 1.00 to 9.00% of the phenotypic variance, indicating the presence of many minor QTLs controlling the resistance. Conclusion: Based on the chromosomal location of some of the known genes, some SNPs may be associated with Bt1, Bt6, Bt11 and Bt12 resistance loci. The remaining significant SNPs may be novel alleles that were not reported previously. Common bunt resistance seems to be an independent trait as no correlation was found between a number of infected heads and chlorophyll content, days to heading or plant height

    Extraordinary Adaptive Plasticity of Colorado Potato Beetle: “Ten-Striped Spearman” in the Era of Biotechnological Warfare

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    Expanding from remote areas of Mexico to a worldwide scale, the ten-striped insect, the Colorado potato beetle (CPB, Leptinotarsa decemlineata Say), has risen from being an innocuous beetle to a prominent global pest. A diverse life cycle, phenotypic plasticity, adaptation to adverse conditions, and capability to detoxify or tolerate toxins make this insect appear to be virtually “indestructible”. With increasing advances in molecular biology, tools of biotechnological warfare were deployed to combat CPB. In the last three decades, genetically modified potato has created a new challenge for the beetle. After reviewing hundreds of scientific papers dealing with CPB control, it became clear that even biotechnological means of control, if used alone, would not defeat the Colorado potato beetle. This control measure once again appears to be provoking the potato beetle to exhibit its remarkable adaptability. Nonetheless, the potential for adaptation to these techniques has increased our knowledge of this pest and thus opened possibilities for devising more sustainable CPB management programs

    Phenotypic performance of transgenic potato (Solanum tuberosum L.) plants with pyramided rice cystatin genes (OCI and OCII)

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    The evaluation of transgenic plants which is usually carried out under controlled conditions in culture rooms and greenhouses can yield valuable information about the influence of introduced genes on a transgenic plant phenotype. However, an overall assessment of plant performance can only be made by testing transgenic plants in the field environment. Thus, the effects of pyramided rice cystatin genes OCI and OCII on morphological parameters of transgenic potato cv. Desiree, Dragacevka and Jelica lines were compared under in vitro, greenhouse, and field conditions. All analyzed OC co-expressing transgenic lines exhibited normal phenotype, both in vitro and in greenhouse conditions. In the field environment, eight of nine OCI/OCII lines were similar to the wild-type control plants in their general phenotypic appearance. Yield parameters, such as tuber number and tuber weight for these phenotypically normal OCI/OCII lines, were also comparable to the controls. Only transgenic cv. Jelica line 4 plants exhibited slightly reduced growth, atypical leaf morphology and, contrary to the plants of other transgenic lines and untransformed controls, failed to flower. However, despite the phenotypic and developmental changes under field conditions, the OCI/OCII Jelica line 4 did not exhibit a significant decrease in tuber yield. Stacking of OCI and OCII genes preserves important attributes of the parental lines, confirming that this approach could be suitable for improving agronomical traits in potato.Serbian Ministry of Education, Science and Technological Development {[}ON173015

    Phenotypic performance of transgenic potato (Solanum tuberosum L.) plants with pyramided rice cystatin genes (OCI and OCII)

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    The evaluation of transgenic plants which is usually carried out under controlled conditions in culture rooms and greenhouses can yield valuable information about the influence of introduced genes on a transgenic plant phenotype. However, an overall assessment of plant performance can only be made by testing transgenic plants in the field environment. Thus, the effects of pyramided rice cystatin genes OCI and OCII on morphological parameters of transgenic potato cv. Desiree, Dragačevka and Jelica lines were compared under in vitro, greenhouse, and field conditions. All analyzed OC co-expressing transgenic lines exhibited normal phenotype, both in vitro and in greenhouse conditions. In the field environment, eight of nine OCI/OCII lines were similar to the wild-type control plants in their general phenotypic appearance. Yield parameters, such as tuber number and tuber weight for these phenotypically normal OCI/OCII lines, were also comparable to the controls. Only transgenic cv. Jelica line 4 plants exhibited slightly reduced growth, atypical leaf morphology and, contrary to the plants of other transgenic lines and untransformed controls, failed to flower. However, despite the phenotypic and developmental changes under field conditions, the OCI/OCII Jelica line 4 did not exhibit a significant decrease in tuber yield. Stacking of OCI and OCII genes preserves important attributes of the parental lines, confirming that this approach could be suitable for improving agronomical traits in potato. [Projekat Ministarstva nauke Republike Srbije, br. ON173015

    Hormonal and metabolic regulation of tomato fruit sink activity and yield under salinity

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    Salinization of water and soil has a negative impact on tomato (Solanum lycopersicum L.) productivity by reducing growth of sink organs and by inducing senescence in source leaves. It has been hypothesized that yield stability implies the maintenance or increase of sink activity in the reproductive structures, thus contributing to the transport of assimilates from the source leaves through changes in sucrolytic enzymes and their regulation by phytohormones. In this study, classical and functional physiological approaches have been integrated to study the influence of metabolic and hormonal factors on tomato fruit sink activity, growth, and yield: (i) exogenous hormones were applied to plants, and (ii) transgenic plants overexpressing the cell wall invertase (cwInv) gene CIN1 in the fruits and de novo cytokinin (CK) biosynthesis gene IPT in the roots were constructed. Although salinity reduces fruit growth, sink activity, and trans-zeatin (tZ) concentrations, it increases the ethylene precursor 1-aminocyclopropane-1-carboxylic acid (ACC) during the actively growing period (25 days after anthesis). Indeed, exogenous application of the CK analogue kinetin to salinized actively growing fruits recovered sucrolytic activities (mainly cwInv and sucrose synthase), sink strength, and fruit weight, whereas the ethylene-releasing compound ethephon had a negative effect in equivalent non-stressed fruits. Fruit yield was increased by both the constitutive expression of CIN1 in the fruits (up to 4-fold) or IPT in the root (up to 30%), owing to an increase in the fruit number (lower flower abortion) and in fruit weight. This is possibly related to a recovery of sink activity in reproductive tissues due to both (i) increase in sucrolytic activities (cwInv, sucrose synthase, and vacuolar and cytoplasmic invertases) and tZ concentration, and (ii) a decrease in the ACC levels and the activity of the invertase inhibitor. This study provides new functional evidences about the role of metabolic and hormonal inter-regulation of local sink processes in controlling tomato fruit sink activity, growth, and yield under salinity

    Root-synthesized cytokinins improve shoot growth and fruit yield in salinized tomato (Solanum lycopersicum L.) plants

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    Salinity limits crop productivity, in part by decreasing shoot concentrations of the growth-promoting and senescence-delaying hormones cytokinins. Since constitutive cytokinin overproduction may have pleiotropic effects on plant development, two approaches assessed whether specific root-localized transgenic IPT (a key enzyme for cytokinin biosynthesis) gene expression could substantially improve tomato plant growth and yield under salinity: transient root IPT induction (HSP70::IPT) and grafting wild-type (WT) shoots onto a constitutive IPT-expressing rootstock (WT/35S::IPT). Transient root IPT induction increased root, xylem sap, and leaf bioactive cytokinin concentrations 2- to 3-fold without shoot IPT gene expression. Although IPT induction reduced root biomass (by 15%) in control (non-salinized) plants, in salinized plants (100 mM NaCl for 22 d), increased cytokinin concentrations delayed stomatal closure and leaf senescence and almost doubled shoot growth (compared with WT plants), with concomitant increases in the essential nutrient K+ (20%) and decreases in the toxic ion Na+ (by 30%) and abscisic acid (by 20-40%) concentrations in transpiring mature leaves. Similarly, WT/35S::IPT plants (scion/rootstock) grown with 75 mM NaCl for 90 d had higher fruit trans-zeatin concentrations (1.5- to 2-fold) and yielded 30% more than WT/non-transformed plants. Enhancing root cytokinin synthesis modified both shoot hormonal and ionic status, thus ameliorating salinity-induced decreases in growth and yield

    The Rhetoric of Fragmentation: Fear and Faith in International Law

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    International audienceAbstractOver the last decade international lawyers have been increasingly concerned with the `fragmentation' of international law. However, given that this expression has been repeatedly used by the profession since the mid-nineteenth century to depict the state of international law, one may wonder about its recent revival in the international legal discourse. Why has it re-emerged? What can we learn from previous invocations? An answer may be sought by contextualizing the fragmentation debate in a historical perspective. This brings out the repetitive and relatively stylized modes in which the profession has narrated legal developments. This essay suggests a correlation between periods of crisis in general and a critical view of fragmentation on the one hand, and periods of scholarly enthusiasm and the prevalence of positive views about fragmentation on the other. This analysis sheds critical light on both the implicit assumptions and political implications of the current debate on fragmentation

    Growth habit and photosynthetic activity of shoot cultures of Medicago sativa L. transformed with the oryzacystatin II gene

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    Abstract Background and Purpose: Introduction of a foreign gene into plant genome may induce morphological and physiological alterations in transgenic plants. The purpose of this study was to assess the impact of gene introduction on morphology and photosynthetic activity of two transgenic alfalfa shoot cultures. Material and Methods: In vitro maintained shoot cultures of alfalfa (Medicago sativa L. cv. Zaječarska 83) that were transformed with the oryzacystatin II (OC-II) gene and propagated on growth regulator-free medium were subjected to analysis of morphological characteristics and photosynthetic activity. For analysis of phological characteristics, the length of the main axis, the number of axillary and adventitious shoots, total number of leaves and the number of senesced leaves as well as plant dry mass were determined. Net photosynthetic rate was determined as CO2 influx using a LI-6200 closed photosynthesis system. Photosynthetic function was assessed as the rate of basic chlorophyll fluorescence and determined with a Plant Stress Meter by method of induced fluorometry. Chlorophyll content in leaf samples was determined spectrophotometrically. Results: The most striking feature of transformed cultures was reduced apical dominance and the absence of adventitious roots. In comparisonwith control, main axis length was also reduced. In addition, a general decrease in photosynthesis in transgenic shoots was also observed. Conclusion: Both morphology and the key processes in photosynthesis were modified in transgenic shoots.However, the fact that transgenic plants carry a gene that confers pest resistance gives potential agronomic value to at least some of the clones whose morphological characteristics and photosynthetic acivity were minimally disturbed
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