PCR-based detection of sunflower white blister rust (<Emphasis Type="Italic">Pustula helianthicola</Emphasis> C. Rost &; Thines) in soil samples and asymptomatic host tissue

Sequencing of partial cox2 (part of the mitochondrial cytochrome-c-oxydase (COX) gene) was performed with samples from the oomycete genus Pustula, the white blister rusts of Asteraceae and related families. Sequence comparison uncovered several single nucleotide polymorphisms (SNPs) between P. spinulosa and host specific strains of Pustula isolated from Senecio vulgaris, Tragopogon pratensis and cultivated sunflower, Helianthus annuus. Based on these differences, specific primers were designed for PCR-based detection of white blister rust strains pathogenic to sunflower. The specificity of the primers was confirmed by cross testing with DNA from various oomycetes occurring in the same locality. The limit of detection for DNA of P. helianthicola was 10 pg. This allowed detection with DNA from single sporangia and single oospores. The PCR-based experiments allowed detection of the presence of sunflower white blister rust in soil samples from fields on which infected plants had been cultivated several months before. Moreover, the molecular tools were successfully applied to trace the pathogen in asymptomatic tissue of infected plants, demonstrating the systemic nature of Pustula on sunflower.     

Spatial variability of O layer thickness and humus forms under different pine beech–forest transformation stages in NE Germany

Spatial variability of humus layer (O layer) thicknesses can have important impacts upon soil water dynamics, nutrient storage and availability, as well as plant growth. The purpose of the present study was to elucidate the impact of forest‐transformation practices on the spatial variability of O layer thicknesses. The study focused on the Kahlenberg forest area (NE Germany) with stands of Scots pine (Pinus sylvestris) and European beech (Fagus sylvatica) of different age structures that form a transformation chronosequence from pure Scots pine stands towards pure European beech stands. Topsoil profiles including both, the O layer and the uppermost humic mineral soil horizon were excavated at intervals of 0.4 m along 15–20 m long transects, and spatial variability of O layer thicknesses was quantified by variogram analysis. The correlation lengths of total O layer thickness increased in the sequence consisting of pure pine stand (3.1 m) → older mixed stand (3.7 m) → pure beech stand (4.5 m), with the exception of the younger mixed stand, for which no correlation lengths of total O layer thickness could be determined. The degree of spatial correlation, i.e., the percentage of the total variance which can be described by variograms, was highest for the two monospecies stands, whereas this percentage was distinctly lower for the two mixed stands. A similar minimum for the two mixed stands was observed for the correlation lengths of the Oh horizon. These results suggest that the spatial structures of forest‐transformation stands may be interpreted in terms of a disturbance (in the form of the underplanting of beech trees). After this disturbance, the forest ecosystem requires at least 100 y to again reach relative equilibrium. These findings are in line with the results of other soil‐related investigations at these sites.     

Taxonomy and evolution of cultivated plants: Literature review 1985/1986

Summary Important papers on taxonomy and evolution of cultivated plants published in 1985 and 1986 were compiled and briefly discussed.

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Taxonomie und Evolution der Kulturpflanzen: Literaturübersicht 1985/1986

Zusammenfassung Wichtige Arbeiten über Taxonomie und Evolution der Kulturpflanzen aus den Jahren 1985 und 1986 wurden zusammengestellt und kurz kommentiert.

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¶rt; : 1985–1986

¶rt; , 1985 1986 . .

     

Zur Samenmorphologie des Kulturmohns (Papaver somniferum L.)

Zusammenfassung Von zahlreichen Sippen der subsp.somniferum sowie von zwei diploiden und mehreren tetraploiden Herkünften der subsp.setigerum (DC.)Corb. vonPapaver somniferum L. wurde die Samenmorphologie vergleichend untersucht. Die Variabilität ist bei subsp.somniferum außerordentlich groß und schließt in sich den Variabilitätsbereich vieler Merkmale beider Ploidiestufen von subsp.setigerum mit ein. Die diploidensetigerum-Sippen lassen sich von vielensomniferum-Sippen anhand der Samen nicht unterscheiden. Die Samen der tetraploiden Sippen lassen sich mit Hilfe von Merkmalen der Samenoberfläche nicht in jedem Fall von Samen besonders kleinsamigersomniferum-Sippen abtrennen. Die Bedeutung der Ergebnisse für die Bearbeitung archäologischer Samenfunde wird kurz diskutiert.

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Seed morphology of cultivated poppy (Papaver somniferum L.)

Summary Length, width and seed coat structure of many different races of subsp.somniferum, of two diploid and several tetraploid races of subsp.setigerum were examined. Subsp.somniferum proved to be extremely variable and to cover also the variability of both chromosome races of subsp.setigerum. By seed morphology, diploid races of subsp.setigerum were not to distinguish from most races of subsp.somniferum, and tetraploid races of subsp.setigerum were difficult to distinguish from small-seeded races of subsp.somniferum. The importance of these findings for determination of archaeological remains of poppy seed is briefly discussed.

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(Papaver somniferum L.)

- subsp.somniferum, subsp.setigerum (DC.) Corb. Pavaver somniferum L. somniferum setigerum. subsp.setigerum subsp.somniferum. , , subsp.somniferum ( ). .

     

Taxonomy and evolution of cultivated plants: Literature review 1983/1984

Summary Important papers on taxonomy and evolution of cultivated plants published in 1983 and 1984 were complied and briefly discussed.

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Taxonomie und Evolution der Kulturpflanzen: Literaturübersicht 1983/1984

Zusammenfassung Wichtige Arbeiten über Taxonomie und Evolution der Kulturpflanzen aus den Jahren 1983 und 1984 wurden zusammengestellt und kurz kommentiert.

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: 1983–1984

, 1983 1984 . .

     

Beziehungen zwischen Kohlenstoff-und Stickstoffmetabolismus bei Pflanzen — eine Übersicht über ausgewählte Aspekte

Zusammenfassung Die mannigfaltigen Wechselbeziehungen zwischen photosynthetischer Kohlenstoffassimilation und N-Metabolismus haben weltweit eine Vielzahl von Untersuchungen stimuliert. Es ist versucht worden, zu einigen ausgewählten Aspekten dieses komplexen Problemkreises eine Übersicht über den gegenwärtigen Kenntnisstand zu geben. Von den Prozessen auf molekularer Ebene wurden besonders der photorespiratorische N-Zyklus und die Beziehungen zwischen Photosynthese und Nitratassimilation berücksichtigt. Auf der organismischen Ebene spielen Wechselwirkungen zwischen Photosynthese und N-Haushalt in bezug auf die Ertragsbildung eine besondere Rolle. Sie wurden am Beispiel des Getreides erörtert. Mathematische Modelle der Photosynthese und Ertragsbildung haben in stärkerem Maße als bisher dem Einfluß des N-Metabolismus Rechnung zu tragen. Daher wurde der Darstellung dieses Problemkreises besondere Aufmerksamkeit gewidmet.

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Interactions between carbon and nitrogen metabolism in plants — a review of some selected topics

Summary The multiple interactions between photosynthetic carbon assimilation and nitrogen metabolism have stimulated worldwide investigations. In the present review some selected topics of this field are discussed. At the molecular level the photo-respiratory nitrogen cycle and relationships between photosynthesis and nitrate assimilation are especially considered. At the whole plant level relationships between photosynthesis and N metabolism are of importance with regard to yield formation of cultivated plants. As an example the situation in cereals is discussed. Mathematical models of photosynthesis and yield formation have to consider the influence of nitrogen metabolism on these processes. Therefore this aspect was treated in some detail.

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—

. . , , . ; . , , .

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Report of a collecting mission to the Georgian SSR 1983 for the study of indigenous material of cultivated plants

Summary In the summer 1983 the joint activities for the collection of autochthonous material of cultivated plants have been continued in the outermost western regions of Georgia (Abkhazia, Megrelia). Altogether 434 accessions could be obtained, more than one third of them being grain legumes, and one fourth vegetables and spice plants, resp. The remaining part includes mainly maize. Gene-erosion is very advanced especially for cereals and some grain legumes besidesPhaseolus vulgaris for which an astonishing genetic variability could be confirmed within the local material. Some details of the accessions regarding botanical interest and breeding value have been outlined. The collecting work should be continued.

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Bericht über eine Reise in die Georgische SSR 1983 zur Sammlung indigenen Materials von Kulturpflanzen

Zusammenfassung Im Sommer 1983 wurde eine weitere gemeinsame Reise zur Sammlung autochthonen Kulturpflanzenmaterials unternommen, die in die westlichen Teile von West-Georgien (Abchasien, Megrelien) führte. Es konnten insgesamt 434 Proben gesammelt werden, von denen mehr als ein Drittel Körnerleguminosen und je etwa ein Viertel Gemüse- und Gewürzpflanzen waren. Getreide war fast ausschließlich durch Mais vertreten. Die Gen-Erosion ist bei Getreide und einigen Körnerleguminosen bereits sehr weit fortgeschritten, während beiPhaseolus vulgaris wiederum eine erstaunliche Vielfalt an Formen festgestellt werden konnte. Besonders interessantes Material von Knoblauch, Blattkohlformen und einigen Spinatgemüsen wird kurz vorgestellt. Die Sammeltätigkeit sollte fortgesetzt werden.

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1983 .

1983 . ¶rt; , (, ). 434 , , . . , . , «» . .

     

Mechanical properties of metastable glacial till before and after water‐induced compaction

The mechanical properties of metastable soils have been approached from different backgrounds by civil engineers and soil scientists, with the main focus being on water‐induced self‐compaction rates. This study was conducted to determine the rebound‐recompression properties of metastable soil before and after wetting and to study the effect of water‐induced compaction on the mechanical stability depending on the overburden pressure. Rebound and recompression properties were measured with oedometer tests using sieved sandy loam, taken from a nonweathered Saalian glacial till layer, as the metastable test soil. The mechanical stability (preconsolidation load) of the dry and wetted soil was derived mathematically from recompression data after the test soil was unloaded. Void‐ratio changes during unloading and reloading were on a low level (Δe = 0.03). Rebound and recompression rates of the dry samples increased with load, whereas the void‐ratio change was twofold higher during recompression. Rebound rates of the wetted samples tended to decrease with load, while the recompression rates remained constant. Preconsolidation load calculated for the dry samples overestimated the simulated overburden pressure, whereas the wetted samples showed a high congruence. In both cases, the point of greatest curvature estimated in the earlier step of deviation gave values that were more realistic to the loads from which the unloading started. Our results indicate that both dry compaction and water‐induced compaction induce primarily plastic deformation. Furthermore, we found that in both the dry and wetted state the mechanical stability of the soil reflecting the overburden pressure remained constant.