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ABSTRACT Leptosphaeria maculans causes blackleg of oilseed rape. Gene-for-gene interactions between race PG3 and Brassica napus cv. Quinta were related to interaction between the fungal avirulence (Avr) gene AvrLm1 and the corresponding resistance gene Rlm1. AvrLm1 isolates were aviru-lent on cvs. Doublol, Vivol, Columbus, and Capitol, and no recombinant phenotypes were observed in the progeny of two AvrLm1 x avrLm1 crosses, suggesting that all of these cultivars may possess Rlm1 or genes displaying the same recognition spectrum, or that a cluster of Avr genes is present at the Avrlm1 locus. In one cross, segregation distortion was observed at the AvrLm1 locus that could be explained by interaction between AvrLm1 and one unlinked deleterious gene, termed Del1. Incompatibility toward cvs. Jet Neuf and Darmor.bzh was governed by a single gene, unlinked to AvrLm1 or Del1. This avirulence gene was termed AvrLm4. Preliminary plant genetic analysis suggested the occurrence of a corresponding dominant resistance gene, termed Rlm4, present in the Quinta line analyzed and linked to Rlm1. 相似文献
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M. Louanchi P. Robin T. Michels M. H. Balesdent D. Despréaux 《European journal of plant pathology / European Foundation for Plant Pathology》1996,102(1):33-44
The aim of these studies is to develop a method for early detection ofRigidopoms lignosus (Basidiomycete, Polyporaceae), the causative agent of white root disease of rubber tree. Two polyclonal sera were produced against soluble mycelial proteins of twoR. lignosus isolates, one from Africa (FCI2), the other from Asia (FID2). The specificity of the antisera was tested using isoelectric focusing (IEF)/Western-blot and DAS-ELISA. The two sera recognized all 20R. lignosus isolates from various geographical origins. The banding patterns obtained by Western-blot enabled a distinction to be made between isolates from Africa and those from Asia. In DAS-ELISA and Western-blot analyses, strong cross reactions were observed withR. ulmarius. Only slight reactions were observed in Western-blot analysis toR. lineatus andP. noxius, both causative agents of root rot inHevea. These cross reactions were not observed under our DAS-ELISA analysis conditions. Finally, no cross reactions were obtained with 9 otherPolyporaceae orHevea root pathogen species. The sensitivity threshold of the DAS-ELISA method was 5 ng ml–1 ofR. lignosus protein. An initial approach to using the DAS-ELISA test for the detection ofR. lignosus in infected plants was carried out on artificially inoculated root samples. The DAS-ELISA protocol enabled detection ofR. lignosus in the root systems of diseased plants. Moreover, no cross reaction was observed with healthy plant extracts. 相似文献
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Susan J. Sprague Marie-Hélène Balesdent Hortense Brun Helen L. Hayden Stephen J. Marcroft Xavier Pinochet Thierry Rouxel Barbara J. Howlett 《European journal of plant pathology / European Foundation for Plant Pathology》2006,114(1):33-40
Resistance of Brassica napus (oilseed rape, canola) conferred by three different major resistance genes has been overcome by changes in virulence of Leptosphaeria maculans populations in France and Australia. In South Australia where B. napus cultivars with major gene resistance derived from Brassica rapa ssp. sylvestris were grown extensively, resistance was rendered ineffective within 3 years of commercial release of the cultivar. Disease
severity was higher on cultivars with sylvestris-derived resistance than cultivars with polygenic resistance. This Australian situation is compared to that in France, where
resistance conferred by the Rlm1 gene was overcome nation-wide in 5 years under commercial cropping practices, and also where a source of resistance introgressed
into B. napus from B. juncea was rendered inefficient in 3 years in experimental field plots near Rennes. 相似文献
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R. Delourme A. M. Chèvre H. Brun T. Rouxel M. H. Balesdent J. S. Dias P. Salisbury M. Renard S. R. Rimmer 《European journal of plant pathology / European Foundation for Plant Pathology》2006,114(1):41-52
The most common and effective way to control phoma stem canker (blackleg) caused by Leptosphaeria maculans in oilseed rape (Brassica napus) is through the breeding of resistant cultivars. Race specific major genes that mediate resistance from the seedling stage
have been identified in B. napus or have been introgressed from related species. Many race specific major genes have been described and some of them are probably
identical in B. napus (allotetraploid AACC) and the parental species B. rapa (diploid AA). More work is needed using a set of well-characterised isolates to determine the number of different major resistance genes
available. In some B. napus cultivars, there is resistance which is polygenic (mediated by Quantitative Trait Loci) and postulated to be race non-specific.
Many of these major genes and Quantitative Trait Loci for resistance to L. maculans have been located on B. napus genetic maps. Genes involved in race specific and polygenic resistance are generally distinct. 相似文献
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A Najafi MH Najafi Z Zanganeh M Sharafi F Martinez‐Pastor H Adeldust 《Reproduction in domestic animals》2014,49(6):934-940
A soybean lecithin‐based extender supplemented with hyaluronic acid (HA) was assayed for effectiveness to improve the quality of frozen–thawed ram semen. HA has not been tested yet in an extender containing soybean lecithin for freezing ram semen. Thus, the aim of this study was to analyse the effects of soybean lecithin at 1% or 1.5% along with HA at 0, 0.5 and 1 mg ml‐1 in a Tris‐based extender on the motion characteristics, membrane integrity (HOST), viability, GSH peroxidase (GSH‐PX) activity, lipid peroxidation and acrosomal status after freezing–thawing. Semen was collected from four Mehraban rams during the breeding season and frozen in the six lecithin×HA extenders. The extender containing 1.5% lecithin supplemented with no HA yielded higher total motility (52.5%±1.6), viability (55.8%±1.6) and membrane integrity (44.5%±1.7), but the effects of the lecithin concentration did not reach signification. Linearity‐related parameters, ALH, BCF, lipid peroxidation, GSH‐PX activity, morphology and acrosomal status were not affected by the extender composition. In general, adding HA significantly decreased sperm velocity (1 mg ml‐1 HA), total motility (only with 1.5% lecithin), viability (1 mg ml‐1 HA for 1% lecithin; both concentrations for 1.5% lecithin) and membrane integrity. In conclusion, adding HA to the freezing extender supplemented with soybean lecithin failed to improve quality‐related variables in ram semen. Increasing the lecithin content could have a positive effect, but further studies are needed. 相似文献
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JI Yun HJ Park MH Park MS Kim JH Choi E Lee SP Gong JM Lim ST Lee 《Reproduction in domestic animals》2014,49(5):705-710
Recently, isolation and in vitro culture of putative spermatogonial stem cells (SSCs) in the domestic cat have been conducted. However, the cellular niche conditions that facilitate the establishment and long‐term maintenance of feline SSCs (FSSCs) have not been described. Therefore, we investigated the type of feeder cells used to stimulate colony formation and growth of FSSCs among the various factors in the FSSC niche. Spermatogonial stem cells isolated from feline testes were cultured on mitotically inactivated testicular stromal cells (TSCs) derived from cats, dogs and mice, and mouse embryonic fibroblasts (MEFs). The formation and growth of colonies derived from SSCs cultured on each type of feeder cell were identified at passage 0, and the morphology, alkaline phosphatase (AP) activity and expression of SSC‐specific genes in surviving colonies were investigated at passage 4. Among these diverse feeder cells, TSCs from cat showed the greatest colony formation, growth and maintenance of FSSCs, and SSC colonies cultured by passage 4 showed a typical dome‐shaped morphology, AP activity and expression of SSC‐specific genes (NANOG, OCT4, SOX2 and CD9). Accordingly, these results demonstrate that feline TSCs could be used as feeder cells to support the establishment and maintenance of SSCs from domestic cats. 相似文献
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Understanding the chemical composition of soil organic matter (SOM) requires the determination of the dynamics of each class of compounds. We measured the dynamics of carbon in neutral carbohydrates by use of natural 13C labelling in an experimental wheat and maize sequence extending over 23 years. The isotopic composition of individual neutral monosaccharides was determined in hydrolysed particle‐size fractions by gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS) of trimethylsilyl (TMS) derivatives. The sensitivity in terms of 13C/12C ratios ranged between 1 and 2‰ depending on the monosaccharide. The age distribution of neutral sugar carbon was very similar to that of total soil carbon. Particulate organic matter (POM) was characterized by the predominance of glucose and xylose of vegetal origin. In POM > 200 µm, the mean age of sugar‐C (5 years) was slightly less than that of total carbon (7 years). Xylose was younger than glucose. The fine fraction 0–50 µm contained mainly glucose, arabinose, galactose, xylose, fucose and mannose, which had predominantly microbial origins. The mean age of carbohydrate carbon in the fraction 0–50 µm was between 60 and 100 years and was similar to that of total organic carbon (OC). No difference in the age of carbon between the individual monosaccharides was found. The POM fraction 50–200 µm had an intermediate signature and turnover. Considering the typical lability of carbohydrates, the relatively great age of carbohydrate carbon may be explained by physical or chemical protection from degradation, as well as by recycling of soil organic matter carbon by soil microbes. 相似文献
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van Putten MH 《Science (New York, N.Y.)》1999,284(5411):115-118
The coalescence of a neutron star and a black hole in a binary system is believed to form a torus around a Kerr black hole. A similarly shaped magnetosphere then results from the remnant magnetic field of the neutron star. In the strong-field case, it contains a cavity for plasma waves located between the barrier of the gravitational potential and the surrounding torus. This cavity may be unstable to superradiance of electromagnetic waves. Superradiant amplification of such waves, initially excited by turbulence in the torus, should inflate into a bubble in a time as short as approximately 0.75 (1 percent/&cjs3539;epsilon&cjs3539;2)(M/7M middle dot in circle) seconds approximately 0.15 to 1.5 seconds, assuming an efficiency &cjs3539;epsilon&cjs3539;2 = 0.5 to 5 percent and a mass M = 7M middle dot in circle. These bubbles may burst and repeat, of possible relevance to intermittency in cosmological gamma-ray bursts. The model predicts gamma-ray bursts to be anticorrelated with their gravitational wave emissions. 相似文献
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N. Poirier S. Derenne J. Balesdent A. Mariotti D. Massiot & C. Largeau 《European Journal of Soil Science》2003,54(2):243-255
Recent studies have pointed to the occurrence in soil organic matter of an insoluble macromolecular fraction, resistant to drastic alkali and acid hydrolysis. This non-hydrolysable fraction may contribute to the stable carbon pool in the soil and thus be important for the global carbon budget. We have developed a method to isolate such chemically resistant components, whilst ensuring complete elimination of the hydrolysable constituents of the organic matter but avoiding the formation of insoluble compounds via Maillard-type condensation reactions. Maize leaves, material especially susceptible to artefact formation, were used for this optimization. Several of the treatments that we tested, including the Klason lignin protocol, proved unsuitable. The most suitable protocol, by progressive hydrolysis with trifluoroacetic and hydrochloric acid, revealed a non-hydrolysable fraction in maize leaves accounting for about 5% by weight of the leaves and corresponding chiefly to lignin and condensed tannins. The protocol was applied to a forest soil and to the soil from an adjacent plot cleared 35 years ago and since cropped continuously with maize. The abundance, chemical composition and sources of the non-hydrolysable fraction of these two soils were determined by a combination of spectroscopy, pyrolysis and electron microscopy. This fraction accounted for about 6% of the total organic carbon of both soils; it contains aliphatic moieties, black carbon, melanoidins and, we think, condensed tannins. 相似文献