Grapevine breeding for resistance to powdery mildew: Bioassay system for evaluation of plant resistance and for characterization of different Uncinula necator strains

Several isolates of Uncinula necator were separated and kept in vitro. The pathogenicity of these isolates was compared by a bioassay system using small leaves issued from in vitro plants; 2 µl of spore suspension was inoculated on these leaves. Significative differences in sporulation time, aggressiveness, sporulation rate and resistance to fungicide triadimenol were observed between these isolates. Host plant variety also affects some of these characters of pathogenicity. The isolates were classified into 2 mating types concerning the aspect of perithecia formation by paired combination between 2 isolates. Productivity of perithecia varied in response to the combination of isolates and to host plant variety

B Stars with and without emission lines, parts 1 and 2

The spectra for B stars for which emission lines occur not on the main sequence, but only among the supergiants, and those B stars for which the presence of emission in H ahlpa is considered to be a significant factor in delineating atmospheric structure are examined. The development of models that are compatible with all known facts about a star and with the laws of physics is also discussed

Sensibilité de variétés de vigne (Vitis vinifera L.) à l'excoriose (Phomopsis viticola Sacci). Distribution du caractère dans quelques descendances

On sait que l'excoriose ne présente pas la même gravité sur tous les cépages. Cependant, les observations qui sont relatées sont rares et fragmentaires c'est pourquoi nous avons entrepris de préciser le comportement d'un certain nombre de cépages de notre collection (plus de 200) vis-à-vis de cette maladie. Les notations effectuées confirment l'existence de grandes différences et ont permis de les chiffrer (notes de O à 5). On peut citer les cépages les moins sensibles: Pinot Meunier, Mourvèdre, Riesling, Cinsaut, Cabernet Franc, Ugni blanc; et parmi les plus sensibles: Chasselas, Semillon, Baroque, Gros Vert, Alphonse Lavallée, Cardinal.Ces observations, lorsqu'elles seront confirmées, pourront orienter, nous semble-t-il, l'application des méthodes de lutte à chaque cépage.Nous avons cherché, dautre part, à préciser le mode de transmission héréditaire de la réaction variétale à la maladie. Pour celà, nous avons mis au point une technique d'inoculation artificielle de rameaux herbacés en survie, assortie d'un mode de notation approprié.Les observations effectuées sur des descendants issus d'autofécondation des deux cépages Merlot et Alicante Bouschet ainsi que sur ceux issus du croisement entre ceux-ci, semblent indiquer une dominance de la moindre sensibilité à l'excoriose. Sensibility of grape varieties (Vitis vinifera L.) to excoriose (Phomopsis viticola Sacc.). Distribution of the character in some progenies It is known that excoriose is not equally severe to ail grape varieties. However, published observations are scanty and fragmentary; we therefore started a study on the behaviour of a number of varieties in our collection (more than 200) to this parasite.Visual scoring on a O to 5 scale confirmed the existence of important differences: Pinot Meunier, Mourvèdre, Riesling, Cinsaut, Cabernet Franc, Ugni blanc ranged among the least susceptible varieties; Baroque, Gros Vert, Alphonse Lavallée, Cardinal, Chasselas, Semillon were among the most susceptible ones.Once these observations are confirmed, they might be useful in adjusting of control methods to each variety.On the other hand, we tried to investigate the inheritance of the varietal response to the parasite. For that purpose, we devised an artificial inoculation technique using eut herbaceous shoots and a scoring scale.Observations on progenies from selfings of the varieties Merlat and Alicante Bouschet, as well as on those of the crossing between these varieties, indicate that low susceptibility to excoriose might be dominant

A technique for improving the germinability of grape seeds for breeding purposes

A method, using bunches from pre-rooted cuttings which are defoliated very early during bud burst, allows the cultivation of fruiting plants in the glasshouse. The germinability of the seeds obtained in this way is improved, which permits, in particular, progenies of an early mutant of the cultivar "Cot", the seeds of which obtained in the field do practically never germinate.Une technique pour améliorer la germinabilité des graines de vigne pour les besoinsde l'améliorationUne technique, consistant à obtenir des grappes sur des boutures préenracinées puis soumises à un effeuillage très précoce au débourrement, permet de cultiver des plantes fructifères en serre. Les graines ainsi obtenues ont une proportion de germination meilleure, ce qui a permis en particulier d'obtenir des descendants d'un mutant précoce du Cot dont les graines obtenues au champ ne germent pratiquement jamais.

High Resolution Chandra Spectroscopy of Gamma Cassiopeia (B0.5IVe)

gamma Cas has long been famous for its unique hard X-ray characteristics. We report herein on a 53 ks Chandra HETGS observation of this target. An inspection of our spectrum shows that it is quite atypical for a massive star, with abnormally weak Fe XXV, XXVI lines, Ly-alpha lines of H-like species from Fe XVII, XXIII, XXIV, S XVI, Si XIV, Mg XII, Ne X, O VII, VIII, and N VII. Also, line ratios of the rif-triplet of for a few He-like ions XVII are consistent with the dominance of collisional atomic processes. Yet, the presence of Fe and Si fluorescence K features indicates that photoionization also occurs in nearby cold gas. The line profiles indicate a mean velocity at rest and a broadening of 500 km/s. A global fitting analysis of the line and continuum spectrum finds that there are 3-4 plasma emission components. The dominant hot (12 keV) component and has a Fe abundance of 0.22 solar. Some fraction of this component (10-30%) is heavily absorbed. The other 2-3 components, with temperatures 0.1, 0.4, 3 keV, are "warm," have a nearly solar composition, a lower column absorption, and are responsible for most other emission lines. The strength of the fluorescence features and the dual-column absorption model for the hot plasma component suggest the presence near the hot sites of a cold gas structure with a column density of 10^23 cm^-2. Since this value is consistent with theoretical estimates of the vertical disk column of this star, these attributes suggest that the X-rays originate near the star or disk. It is possible that the Fe anomaly in the hot component is related to the First Ionization Potential effect found in coronal structures around active cool stars. This would be yet another indication that the X-rays -rays are produced in the immediate vicinity of the Be star.Comment: 32 pages, 4 figures (Fig. 3 colorized.) To be published in 01/10/04 Astrophysical Journal, Main Journal; included figures and updated formattin

Amélioration du rendement du bouturage des extrémités après thermothérapie sur plantes en pots par l'utilisation de la culture sur milieu nutritif gélosé stérile

L'enracinement sous brouillard d'extrémités de tiges prélevées sur des plantes en pots après le traitement thermique se révèle souvent décevant (20 à 25%). Ces extrémités, mises stérilement en culture sur milieu nutritif gélosé, ne sont que rarement contaminées par des champignons ou des bactéries (moins de 3%), et l'on obtient ainsi un nombre élevé de plantes établies au champ à partir des extrémités implantées (82%).lmprovement of the shoot-tip yield of heat treated pot plants using culture on agar nutrient medium under sterile conditionsRooting shoot-tips from heat treated pot plants under mist proved very unsuccessfull (20 to 25%). Use of culture on agar nutrient medium under sterile conditions with these shoot tips resulted in a surprisingly low fungal and bacterial contamination rate (less than 3°/o) and a very high proportion of successfull establishment of plants in the field from the shoot-tip inplants (82%)

The Remarkable Be Star HD110432

HD110432 has gained considerable attention because it is a hard, variable X-ray source similar to gamma Cas. From time-serial echelle data obtained over two weeks during 2005 January and February, we find several remarkable characteristics in the star's optical spectrum. The line profiles show rapid variations on some nights which can be most likely be attributed to irregularly occurring and short-lived migrating subfeatures. Such features have only been observed to date in gamma Cas and AB Dor, two stars for which it is believed magnetic fields force circumstellar clouds to corotate over the stellar surface. The star's optical spectrum also exhibits a number of mainly FeII and HeI emission features with profiles typical of an optically thin disk viewed edge-on. Using spectral synthesis techniques, we find that its temperature is 9800K +/-300K, that its projected area is a remarkably large 100 stellar areas, and its emitting volume resides at a distance of 1 AU from the star. We also find that the star's absorption profiles extend to +/-1000 km/s, a fact which we cannot explain. Otherwise, HD110432 and gamma Cas share similarly peculiar X-ray and optical characteristics such as high X-ray temperature, erratic X-ray variability on timescales of a few hours, optical emission lines, and submigrating features in optical line profiles. Because of these similarities, we suggest that this star is a new member of a select class of "gamma Cas analogs."Comment: 31 pages, 9 figures, accepted by ApJ (3/20/06

Relationship and patterns of distribution among grapevine viroids from California and Europe

Analyses of California and European grapevine sources indicated a ubiquitous occurrence of viroids in these materials. Hybridization results indicated sequence homology to both GV-1 and GV-3 for viroids of varieties grown in California as well as from European sources. Wine and rootstock varieties contained a greater proportion of the more common GV-1 plus GV-3 viroid profile, whereas the table varieties contained a larger proportion of the relatively unusual viroid profile of GV-1, -2, and-3. An unexpected divergence of four viroid profiles emerged in the rootstock species. These profiles were 1) Gv-1, -2, and -3, 2) GV-1 plus GV-3, 3) GV-3, and 4) viroid-free. V. californica was the only grapevine analyzed which was found to be viroid-free

Estimation de la capacité photoautotrophique de vitroplants de porte-greffe de vigne (var. Gravesac): mise au point d'un système de mesure de la photosynthèse nette de vitroplants

La capacité photosynthétique de vitroplants de vigne (var. Gravesac) a été déterminée à l'aide d'un dispositif de mesures des échanges gazeux en circuit ouvert. L'activité photosynthétique et la respiration de la plante sont importantes en culture in vitro. La photosynthèse nette maximale est de 2 µmol m-2 s-1 a 500 µ11-1 de CO2. A 350 µ11-1 de CO2 la photosynthèse est de 1,6 µmol m-2 s-1. La respiration a l'obscurité est de 0,018 µmol s-1 g-1 de poids sec total. La quantité totale des sucres solubles dans le milieu de culture reste constante pendant les deux mois de culture. Le saccharose est totalement hydrolysé en glucose et en fructose. Les vitroplants de Gravesac ne prélèvent pas de sucres dans le milieu, ce qui confirme leur degré élevé d'autotrophie dans ces conditions de culture. La comparaison entre les échanges gazeux de vitroplants et des plantes cultivées en serre met en évidence une réduction de 80% de l'activité in vitro.Evaluation of the photoautotrophic ability of Vitis plantlets (rootstock var Gravesac): Set-up of a special open flow gas exchange systemThe photosynthetic ability of Vitis rootstock plantlets (var. Gravesac) was estimated in vitro with an open flow system specially designed for in vitro culture. CO2 response curves were established and respiration was also measured. The maximum net photosynthetic rate, reached at 500 µ11-1 of CO2, is 2 µmol m-2 s-1. At 350 µ11-1 CO2 the photosynthetic activity is 1.6 µmol m-2 s-1. The dark respiration rate is 0.018 µmol s-1 g-1 of total dry weight. The total amount of soluble carbohydrates in the medium remains the same whether plantlets were present or not. In the medium with plantlets, the sucrose is entirely hydrolysed in glucose and fructose within two months. No carbohydrate uptake from the medium was recorded indicating an autotrophic behaviour. Measurements of CO2 exchange were also performed at leaves of plants cultivated in a greenhouse. The photosynthetic activity of in vitro plants accounts only for 20% of the level of greenhouse-grown plants