162 research outputs found

    Screening pearl millet germplasm for tolerance to soil salinity

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    Saline soils account for up to 580 million ha worldwide and are widespread In arid and semi-arid regions (Rengasamy 2002). Pearl millet [Pennisetum glaucum) is often grown In saline soils and Is known to be relatively better In tolerance to salinity than other crops, particularly maize (Zea mays) or legumes (Ashrafand McNeilly 1987, Dua 1989). However, a well-focused search can lead to the Identification of genotypes with superior tolerance. Since pearl millet Is usually grown rainfed with minimum Input, It Is all the more Important to genetically Improve the adaptation of this crop to soil salinity. The Improved salinity tolerant lines together with cultural management options provide greater scope for Improving the crop productivity in these saline soils

    Mélanome endobronchique

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    Le mélanome malin a un potentiel métastatique important. Les métastases pulmonaires du mélanome sont communes cependant la localisation endobronchique reste rare et pose le problème de son origine primitive ou secondaire. Nous rapportons le cas d’un mélanome pulmonaire qui présente des particularités intéressantes: une lésion cutanée présumée primitive totalement régressive, la présentation radio clinique mimant parfaitement un cancer bronchique primitif, un aspect endoscopique bourgeonnant et grisâtre dont l’étude histologique a permis de poser le diagnostic, une agressivité tumorale avec une extension intracardiaque et bourgeon tumoral intra cavitaire. A travers cette observation, les auteurs étudient les caractéristiques radio-cliniques pouvant distinguer le mélanome pulmonaire primitif du secondaire; la localisation endobronchique avec une revue de la littérature sur les métastases endo bronchiques; le bilan d’extension à entamer en cas de mélanome pulmonaire ainsi que les difficultés thérapeutiques posés par ce type de lésion dont le pronostic reste péjoratif

    Evaluation of transgenic groundnut lines under water limited conditions

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    The transpiration response of 14 transgenic groundnut genotypes to water deficit was studied under greenhouse conditions and compared with that of JL 24 (control). Plants were grown under well-watered conditions until 19 days after sowing, after which the plants were saturated with water then subjected to drought stress (absence of irrigation). JL 24 started to show wilting symptoms (loss of turgor) after 21 days of stress, after which severe symptoms were evident in this line. JL 24 reached the stage III (normalized transpiration rate or NTR <0.1) after 27 days. Wilting symptoms were not observed in the transgenic lines even after 21 days. Thereafter, these lines exhibited various levels of wilting symptoms, with a few transgenic lines showing no symptoms, and lines RD 14, RD 22 and RD 25 showing reduced levels of symptoms compared to JL 24. The transgenic lines varied largely in the number of days to reach the end point. RD 14 reached the end point in 29 days, whereas RD 4 reached the endpoint in 52 days. Data on NTR, fraction of transpirable soil water, and number of days to end point were subjected to average linkage cluster analysis for the development of a dendrogram. This dendrogram showed that the lines could be classified into 4 groups, which clearly distinguished the water use pattern among these lines, suggesting that the transgenic lines varied in their stomatal response to water deficit

    Identification of pearl millet [Pennisetum glaucum (L.) R.Br.] lines tolerant to soil salinity

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    Crop tolerance to salinity is of high importance due to the extent and the constant increase in salt-affected areas in arid and semi-arid regions. Pearl millet (Pennisetum glaucum), generally considered as fairly tolerant to salinity, could be an alternative crop option for salt affected areas. To explore the genotypic variability of vegetative-stage salinity tolerance, 100 pearl millet lines from ICRISAT breeding programs were first screened in a pot culture containing Alfisol with 250 mM NaCl solution as basal application. Subsequently, 31 lines including many parents of commercial hybrids, selected from the first trial were re-tested for confirmation of the initial salinity responses. Substantial variation for salinity tolerance was found on the basis of shoot biomass ratio (shoot biomass under salinity/ non-saline control) and 22 lines with a wide range of tolerance varying from highly tolerant to sensitive entries were identified. The performance of the genotypes was largely consistent across experiments. In a separate seed germination and seedling growth study, the seed germination was found to be adversely affected (more than 70% decrease) in more than half of the genotypes with 250 mM concentration of NaCl. The root growth ratio (root growth under salinity/control) as well as shoot growth ratio was measured at 6 DAS and this did not reflect the whole plant performance at 39 DAS. In general, the whole plant salinity tolerance was associated with reduced shoot N content, increased K+ and Na+ contents. The K+/Na+ and Ca++/Na+ ratios were also positively related to the tolerance but not as closely as the Na+ content. Therefore, it is concluded that a large scope exists for improving salt tolerance in pearl millet and that shoot Na+ concentration could be considered as a potential non-destructive selection criterion for vegetative-stage screening. The usefulness of this criterion for salinity response with respect to grain and stover yield remains to be investigated

    Development of crop cultivars for increased and stable production in dry lands of the semi-arid tropics

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    Increasing the grain yield and its stability in dry lands of the tropics of Asia and Africa, as the horne to a vast impoverished humanity,'contipues to be a major challenge for agricultural research and development Development of genetically enhanced cultivars with high yield potential, appropriate maturity, an'd resistance to biotic and abiotic stress factors is an effective approach to increasing and stabilizing the production in these regions. Advances possible through this approach are illustrated with the impacts made in pearl millet (Pelllliselul11 glaucum), a warm~season cereal; and chickpea (Cicer arielillum), a cool-season legume, which are amongst the five mandate crops of the International Crops Research Institute for the Semi-arid Tropics (ICRISAn. The research in this paper is largely the work done by ICRISAT in partnership with the national agricultural research systems and advanced research institutes. The convention,!l approach of enhancement both in pearl millet ang chickpea has been highly successful. Progress has also been made in the areas of molecular marker-assisted selection in both crops, and in wide hybridization and transgenic technology in chickpea to improve those traits that are less amenable to genetic manipulation through conventional methods of genetic enhancement

    Relationships Between Transpiration Efficiency and Its Surrogate Traits in the rd29A:DREB1A Transgenic Lines of Groundnut

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    Transpiration efficiency (TE) contributes to crop performance under water-limited conditions, but is difficult to measure. Herein, we assess the relationships between TE and surrogate traits and how these interact with water regimes, using isogenic materials: five transgenic events of groundnut and their wild-type (WT) parent JL 24, among which large variation in TE was previously reported. These five events came from the insertion of transcription factor DREB1A from Arabidopsis thaliana, driven by stress responsive promoter rd29. The events were in T3 generation and had been selected from a preliminary trial for having a large range of variation in the time needed to deplete soil moisture upon exposure to soil drying. Two experiments were conducted, in each case with plants exposed to well-watered (WW) and water-stressed (WS) conditions. Significant correlations were found between TE and soil plant analysis development chlorophyll meter readings (SCMR), TE and specific leaf area (SLA), and SLA and SCMR in both experiments. Nevertheless, these significant relationships were confined to the drought stress (DS) treatment. No correlation between TE and Δ13C (carbon isotope discrimination) was found in the present study, regardless of the water regime, and in none of the two experiments. A significant negative correlation was established between TE and the fraction of transpirable soil water (FTSW) threshold values where transpiration declined upon soil drying, in both experiments. The mean vapour pressure deficit in the two different seasons (1.47 kPa and 0.73 kPa) did not affect the ranking of genotypes for TE. It is concluded that surrogates for TE, when used, need careful consideration of the drought stress status of plants at the time of measurement, and that differences in TE might be closely related to how plants respond to soil drying, with high TE genotypes maintaining gas exchange until the soil is dryer than low TE genotypes

    Stress-inducible expression of At DREB1A in transgenic peanut (Arachis hypogaea L.) increases transpiration efficiency under water-limiting conditions

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    Water deficit is the major abiotic constraint affecting crop productivity in peanut (Arachis hypogaea L.). Water use efficiency under drought conditions is thought to be one of the most promising traits to improve and stabilize crop yields under intermittent water deficit. A transcription factor DREB1A from Arabidopsis thaliana, driven by the stress inducible promoter from the rd29A gene, was introduced in a drought-sensitive peanut cultivar JL 24 through Agrobacterium tumefaciens-mediated gene transfer. The stress inducible expression of DREB1A in these transgenic plants did not result in growth retardation or visible phenotypic alterations. T3 progeny of fourteen transgenic events were exposed to progressive soil drying in pot culture. The soil moisture threshold where their transpiration rate begins to decline relative to control well-watered (WW) plants and the number of days needed to deplete the soil water was used to rank the genotypes using the average linkage cluster analysis. Five diverse events were selected from the different clusters and further tested. All the selected transgenic events were able to maintain a transpiration rate equivalent to the WW control in soils dry enough to reduce transpiration rate in wild type JL 24. All transgenic events except one achieved higher transpiration efficiency (TE) under WW conditions and this appeared to be explained by a lower stomatal conductance. Under water limiting conditions, one of the selected transgenic events showed 40% higher TE than the untransformed control

    Using Genomics to Exploit Grain Legume Biodiversity in Crop Improvement

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    Following a brief introduction on the phylogeny, taxonomy, production, uses, diseases, pests, environmental stress and variation in genomes of grain legumes, this review focuses on the available genetic resources of key legume crops (tropical and temperate legumes, and model species related to grain legumes); management and utilization of legume genetic resources; impact of genetic resources in conventional legume breeding (germplasm distribution, domesticated germplasm and breeding gains, wild germplasm, conventional manipulation of genetic resources); enhanced molecular strategies for manipulating novel genetic variation for legume breeding (interspecific hybridization, linkage mapping and QTL detection, linkage disequilibrium and association mapping, dissection and manipulation of legume physiology); advanced applications in legume molecular breeding (comparative genomics and allele mining, functional genomics and gene discovery, new technologies for marker-assisted selection, and molecular breeding in legume

    Pseudotumoral tracheobronchial amyloidosis mimicking asthma: a case report

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    <p>Abstract</p> <p>Introduction</p> <p>Tracheobronchial amyloidosis is an uncommon localized form of amyloidosis that can simulate a tracheal tumor. Clinical signs are not specific and the diagnosis is rarely given before performing a bronchoscopy with multiples biopsies.</p> <p>Case presentation</p> <p>We report the case of a 60-year-old Moroccan woman, complaining of dyspnea and wheezing for three years, who was treated at our institution for management of severe asthma. A bronchoscopy revealed a tumor formation of her trachea; multiples biopsies were performed and a diagnosis made of amyloid light-chain amyloidosis. She successfully received an endoscopic resection.</p> <p>Conclusion</p> <p>This case highlights the importance of routinely carrying out an endoscopy in any patient complaining of atypical bronchial symptoms or with uncontrolled asthma. Tracheal amyloidosis is a rare disease, confirmed by histological examination of bronchial biopsies, and the treatment of choice is based on the bronchoscopic resection.</p
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