排序方式： 共有10条查询结果，搜索用时 15 毫秒
1
1.
Résumé En comparaison avec des méthodes de tests de résistance déjà décrits, un procédé faisant appel au bouturage est indiqué et
ses résultats comparés. Ce procédé consiste à prélever des boutures sur des plantes issues de semis de graines et à les cultiver
sur milieu gélosé simple coulé en bo?te de Pétri. Des larves deGlobodera sp. sont déposées sur les racines en quantité connue et la résistance est appréciée par le rapport ‘femelles développées/larves
inoculées’.
Cette méthodologie est d'une sensibilité 3 à 4 fois plus grande que celle des autres tests connus, décrits et utilisés. En
outre, elle permet d'indiquer dans un délai maximum de 3 mois après semis le niveau individuel de résistance àGlobodera sp. Ceci correspond pour le sélectionneur à un gain de temps et de travail appréciable.
Summary Traditional methods to determine resistance of potato cultivars to cyst nematodes, genusGlobodera, cannot readily be used on plantlets grown from true seed. Because the root system is poorly developed with respect to the inoculum level commonly used, the percentage of resistant seedlings is overestimated. A method using stem cuttings is described: cuttings are taken from potato seedlings, held for 7 days at 20°C in a growth medium which favours rooting, then washed and placed on water agar (15 g/l) in Petri dishes. L2 larvae are inoculated at the rate of 3 larvae/root as soon as the roots have grown. Resistance is expressed in terms of the ratio ‘developed females/inoculated larvae’. This method has been compared to others traditionally quoted and used. The adopted model is straightforward: dominant monogenic resistance and a material with no resistance toG. rostochiensis Rol (Table 1). Each plantlet is tested using different methods (Table 2). The procedure using stem cuttings and inoculation in Petri dishes is the most sensitive one and is less subject to errors (Table 3). In practice, it allows the breeder to determine the level of resistance of each specimen within 3 months after sowing. The saving in time and work which can be achieved in a breeding programme must be offset against the high cost of the work which has to be done during a short time.
Zusammenfassung Die klassischen Tests zur Prüfung der Resistenz der Kartoffeln gegen die Zystennematoden der GattungGlobodera sind, im allgemeinen, nicht anwendbar zur Prüfung von aus Samen entsprungenen Pfl?nzlingen. Der Prozentsatz der als Resistent betrachteten Pflanzen wird übersch?tzt. Diese übersch?tzung ist auf die schwache Wurzelentwicklung gegenüber dem verwendeten Impfstoff zurück zu führen. Ein mit Stecklingen arbeitendes Verfahren wird beschrieben: Stecklinge von Kartoffeln werden von aus Samen entsprungenen Pfl?nzlinge gewonnen, 7 Tage lang bei 20°C in einem die Verwurzelung begünstigenden N?hrmedium angesetzt, gewaschen und in eine L?sung von 15 g geliertes Wasser pro Liter, in Petrischalen gesetzt. Mit Beginn der Verwurzelung werden infizierende Larven L2 eingeimpft und zwar je 3 L2 pro Wurzel. Die Resistenz wird nach dem Verh?ltnis ‘entwickelte Weibchen/eingeimpfte Larven’ gesch?tzt. Dieses Verfahren wird mit anderen, oft genannten und verwendeten, verglichen. Das gew?hlte Modell ist einfach: Dominierende monogenetische Resistenz und Material ohne Resistenz gegenüberG. rostochiensis Rol (Tab. 1). Jeder Pfl?nzling wird auf mehrere verschiedene Arten getestet (Tab. 2). Der Prozess, welcher mit Stecklingen und Einimpfung in Petrischalen arbeitet, erweist sich als der empfindlichste und mit am wenigsten Fehler behaftete Test (Tab. 3). In der Praxis erm?glicht er dem Züchter, bis sp?testens 3 Monate nach der Saat, das Resistenzniveau der einzelnen Pflanzen zu bestimmen. Der Vorteil des Zeit- und Arbeitgewinnes für ein Zuchtprogramm wird durch einen grossen Arbeitsaufwand w?hrend der kurzen Zeit der Verwirklichung der Tests ausgeglichen.相似文献
2.
Reduced dispersal of native plant species as a consequence of the reduced abundance of frugivore species in fragmented rainforest 总被引：1，自引：0，他引：1
Frugivorous animals disperse the seeds of the majority of rainforest plant species and hence play a key role in the trajectory of rainforest regeneration. This study investigated whether changes in the species composition of the frugivore community in fragmented rainforest in subtropical Australia is likely to impact the dispersal of native plant species. The potential of frugivorous bird and bat species to disperse the seeds of plant species in fragmented rainforest was assessed using published dietary information together with field surveys of frugivore abundance within intact forest, forest fragments and patches of regrowth. Frugivore species with reduced abundance in fragmented rainforest were the only known dispersers of 27 of the 221 native plant species in the data set (12% of species). These frugivore species were also major dispersers of plant species producing fruits wider than 10 mm and species from the families Rubiaceae, Lauraceae, Myrtaceae, Meliaceae, Lamiaceae and Vitaceae. Except for Rubiaceae, these plant taxa are also potentially dispersed by two of the frugivore species that were widespread in fragmented rainforest, Lopholaimus antarcticus and Ptilonorhynchus violaceus, although dispersal rates are likely to be lower in fragmented than in extensive rainforest. Consistent with other regions, large-seeded plants are susceptible to reduced dispersal in fragmented rainforest in subtropical Australia. However, we predict a smaller deficit in seed dispersal in fragmented forests than has been reported from other regions, due to factors such as functional overlap among frugivore species, the ability of many Australian rainforest vertebrates to persist in fragmented rainforest, and a lack of hunting in these forests. Nevertheless, rainforest fragmentation has reduced the abundance of a suite of frugivorous rainforest fauna, which in turn is likely to reduce the dispersal of a certain plant taxa and may alter patterns of plant regeneration in subtropical Australian rainforest fragments. 相似文献
3.
Correlated effects of exotic pollen‐fertility restorer genes on agronomic and quality traits of hybrid rye 
下载免费PDF全文
下载免费PDF全文 Thomas Miedaner Cathérine Pauline Herter Heike Goßlau Peer Wilde Bernd Hackauf 《Plant Breeding》2017,136(2):224-229
In CMS (cytoplasmic male sterility)‐based hybrid rye (Secale cereale L.) breeding, effective pollen‐fertility restoration is an essential prerequisite for achieving maximum grain yield on the one hand and for minimizing ergot (Claviceps purpurea) infestation on the other. Restorer genes for the CMS‐inducing ‘Pampa’ cytoplasm derived from landraces collected in Iran and Argentina are used by breeders for achieving this goal. Here, restorer genes from four germplasm sources (‘Altevogt 14160’, ‘IRAN III’, ‘Trenelense’ and ‘Pico Gentario’) were analysed by producing three‐way cross hybrids between an elite CMS single cross and pollinators with and without a given restorer gene. Materials were evaluated on large drilled plots for restorer index (RI), grain yield, plant height and other traits in six environments. In experiment 1, a restorer gene from ‘Altevogt 14160’ was used. Seven pairs of marker‐selected carrier and non‐carrier backcross lines served as pollinators. In experiment 2, the pollinators were 17 backcross line pairs from the other three germplasm sources. These lines were grouped as high (RI > 67%) and low restorers (RI < 30%), respectively, using testcrosses with a highly diagnostic CMS tester. Hybrids carrying an exotic restorer gene suffered from a significant grain yield reduction by 4.4% and 9.4% and were 9.3 and 4.8 cm taller in experiments 1 and 2, respectively. Thousand‐kernel weight was reduced, whereas quality traits were only slightly affected. For all traits, significant genetic variance existed among the testcrosses to the presence vs. absence of a given exotic restorer gene. This offers a chance for the breeder to reduce or ultimately overcome the presently observed performance reductions brought about by exotic restorer genes. 相似文献
4.
Cliffe LJ Humphreys NE Lane TE Potten CS Booth C Grencis RK 《Science (New York, N.Y.)》2005,308(5727):1463-1465
The functional integrity of the intestinal epithelial barrier forms a major defense against invading pathogens, including gastrointestinal-dwelling nematodes, which are ubiquitous in their distribution worldwide. Here, we show that an increase in the rate of epithelial cell turnover in the large intestine acts like an "epithelial escalator" to expel Trichuris and that the rate of epithelial cell movement is under immune control by the cytokine interleukin-13 and the chemokine CXCL10. This host protective mechanism against intestinal pathogens has implications for our wider understanding of the multifunctional role played by intestinal epithelium in mucosal defense. 相似文献
5.
6.
Delesalle C Dewulf J Lefebvre RA Schuurkes JA Proot J Lefere L Deprez P 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》2007,21(2):293-301
BACKGROUND: Intestinal hypoperfusion can lead to increased lactate concentrations in plasma and peritoneal fluid of horses with colic. HYPOTHESIS: The purposes of this study were to (1) evaluate the reliability of the Accusport analyzer to assess peritoneal fluid lactate (PFL) concentrations in healthy horses and those with colic, (2) identify clinical features associated with abnormal blood plasma lactate (BPL) and PFL concentrations, and (3) evaluate the prognostic value of BPL and PFL. ANIMALS: BPL and PFL were determined in 20 healthy horses and in 106 horses with colic. RESULTS: The Accusport was reliable for determining BPL concentrations < 13 mM and PFL concentrations < 20 mM. Multivariate analysis indicated that PCV and the need for intestinal resection were independently associated with the BPL; pulse, PCV, venous pO2, the presence of necrotic intestine, an increased amount of peritoneal fluid, and fluid total protein content were independently associated with PFL. With a 1 mM increase in BPL or PFL, the respective odds ratios for required abdominal surgery increase to 1.23 (BPL) and 1.58 (PFL), odds ratios for a required intestinal resection increase to 1.20 (BPL) and 1.41 (PFL), and odds ratios for developing ileus increase by 1.33 (BPL) and 1.36 (PFL). PFL concentrations of 1, 6, 12, and 16 mM correspond to a probability of death of 11, 29, 63, and 82%, respectively, in horses without strangulating obstruction and of 25, 52, 82, and 92%, respectively, in horses with strangulating obstruction. CONCLUSION: PFL is more useful and sensitive than BPL for prognostic purposes in horses with colic. 相似文献
7.
8.
9.
10.
Résumé Une méthode de test de descendance àGlobodera rostochiensis est décrite. Elle consiste à inoculer un faible nombre de larves sur des racines issues de graines cultivées en bo?tes de
Pétri. L'analyse s'effectue à la simple lecture du nombre de femelles développées par plantule et à l'analyse des fréquences
observées. Les croisements utilisés proviennent de parents non résistants, totalement résistants ou partiellement résistants.
La comparaison des résultats obtenus des descendances issues de parents à résistance totale avec ceux obtenus à partir de
descendances provenant de parents non résistants permet d'étudier la validité et l'intérêt de ce type de test. Un inoculum
de 3 larves par racine est trouvé satisfaisant. Accessoirement, le déterminisme épigénique deG. rostochiensis est confirmé.
Summary A method is described to test the inheritance of resistance toG. rostochiensis. About 100 true seeds from each cross are placed on water agar in Petri dishes and subsequently inoculated with 3–5 larvae per seedling. The number of females per seedling is determined 15 days later and the corresponding frequencies tabulated. The method has been examined using the progeny of crosses between susceptible, partially resistant and resistant parents. A theoretical model of the frequency of the numbers of females per seedling has been developed based on the results obtained with susceptible parents and two inoculum levels (Table 3). Other models have then been constructed based on a dominant monogenic hypothesis of resistance heredity (Table 4). The hypothesis has been verified and the validity of the method assessed at the same time by comparing the results obtained with the other types of crosses (susceptible × resistant and resistant × resistant) with those predicted by the models (Table 5). Because of competition which is related to the epigenic character of sex inG. rostochiensis, a fact which has been confirmed here, an inoculum level of 3 larvae per root is apparently optimal (Tables 2 and 6).
Zusammenfassung Eine Testmethode zur Prüfung der Resistenz der Nachkommenschaft gegenüberG. rostochiensis wird beschrieben. Sie besteht darin die Samen von Kartoffeln in eine, in Petrischalen gegossene, gelierte N?hrl?sung abzulegen. Je Nachkommenschaft werden hundert Samen verwendet. Pro Pfl?nzling werden 3 bis 5 Larven abgesetzt. Zwei Wochen sp?ter wird die Anzahl der entwickelten Weibchen pro Pfl?nzling gez?hlt und eine Tabelle der entsprechenden H?ufigkeit erstellt. Die beschriebene Methode wurde auf Nachkommenschaften geprüft welche von nicht widerstandsf?higen, teilweise widerstandsf?higen und v?llig widerstandsf?higen Eltern abstammen. Die ab nicht widerstandsf?higer Eltern erhaltenen Resultate erlauben es, ein theoretisches Modell über die H?ufigkeit der Anzahl pro Pfl?nzling gebildeter Weibchen zu erstellen und dies auf Bezug der beiden verwendeten Impfdosen (Tab. 3). Weitere Modelle werden nach der Hypothese einer monogenetischer dominierender Vererbung gebildet (Tab. 4). Verglichen mit den Resultaten von Kreuzungen simplex × nulliplex und simplex × simplex erlauben sie es diese Eigenschaft und somit auch die Gültigkeit des beschriebenen Tests zu best?tigen (Tab. 5). Aus Gründen der an den epigenischen Charakter des Geschlechts vonG. rostochiensis gebunden Konkurenzkampfes, hier wiederum best?tigt, erscheint die Dosis von 3 Larven pro Wurzel die optimale Dosis zu sein (Tab. 2 und 6).相似文献
1