The requirement for exopolysaccharide precedes the requirement for flavolan-binding polysaccharide in nodulation of Leucaena leucocephala by Rhizobium loti

Rhizobium loti strain PN4115 (NZP2213 str-1) ineffectively nodulates Leucaena leucocephala, i.e., strain PN4115 induces nodulation (Nod⁺) and is able to invade these nodules (Inv⁺), but fails to fix nitrogen (Fix^–). Strain PN4115 does not synthesize a flavolan-binding polysaccharide (FBP), which is synthesized by the fully effective (Nod⁺Inv⁺Fix⁺) R. loti strain PN184 (NZP2037 str-1). The FBP may offer protection from prodelphinidin-rich flavolans synthesized by Lc. leucocephala. In this work, we show that exopolysaccharide (EPS)-negative mutants derived from strain PN4115 have a more severe ineffective phenotype (Nod⁺Inv^–Fix^–) on Lc. leucocephala than strain PN4115. This suggests that EPS from strain PN4115 is functional during invasion of Lc. leucocephala and that the requirement for EPS precedes the requirement for FBP. Received: 8 October 1996 / Accepted: 11 December 1996     

Characterization of rhizobia nodulating Lotus subbiflorus from Uruguayan soils

Generation times, acid production, carbon utilization, immunological properties, plasmid content, protein profile and symbiotic properties of 15 isolates of rhizobia nodulating Lotus subbiflorus were studied. Based on specific growth rates, carbon source utilization and acid production, 13 out of the 15 isolates could be assigned to the slow-growing group of rhizobia (bradyrhizobia). Using antisera against whole cells of three isolates, we separated the 15 isolates into three serogroups. Only the slow-growing isolate Ls4 and the fast-growers Ls5 and Ls552 lacked cross-reactivity with any of the sera tested. Electrophoretic mobilities of whole cell protein from seven out of the eight isolates included in the serogroup represented by strain Ls31 were identical. Similarly, isolates Ls1B3 and Ls1B4, both in serogroup Ls1B3, had the same pattern of cell proteins. In contrast, isolates Ls3 and Ls7, belonging to serogroup Ls7, differed in protein profile. Plant growth experiments carried out under bacteriologically controlled conditions revealed that all of the isolates effectively nodulated L. subbiflorus and L. pedunculatus, but were unable to form effective nodules on L. tenuis and L. corniculatus. All isolates showed similar effectiveness in symbiosis with L. subbiflorus, except isolate Ls7, which gave significantly higher plant dry weight.Abbreviations ELISA enzyme linked immuno-sorbent assay - kDa kiloDalton - MM mineral medium - PBS phosphate-buffered saline - RE relative efficiency - SDS-PAGE sodium dodecyl sulfate-polyacrylamide gel electrophoresis - YEM deyeast extract mannitol     

Acclimatization trials of someSolanum species from Amazonas Venezuela at the botanical garden of Padova

Acclimatization trials of the two tropical speciesSolanum sessiliflorum (cocona) andSolanum stramonifolium (coconilla) from Amazonas Venezuela, were carried out at the Botanical Garden of Padua.S. sessiliflorum exhibited a greater difference between the Botanical Garden and the native environment. Plant growth was reduced and pollination was difficult; despite numerous blooms few fruits were produced. Moreover, some fruit abscised early and the persistent ones were still unripe at the end of the season. On the contrary,S. stramonifolium showed good adaptation to the new environmental conditions. The plants grew well and produced a lot of ripe berries. Self-pollination as well as cross-pollination by bumblebees (Bombus terrestris) and other insects present in the open air succeeded. Thus, this latter species could be regarded as potentially exploitable in temperate climates as well as in Venezuela.     

Effect of lucerne saponins and Lotus condensed tannins on survival of grass grub,Costelytra zealandica

Abstract

Crude extracts of lucerne (Medicago sativa) and Lotus pedunculatus root were toxic when administered orally to third-instar Costelytra zealandica larvae. Purified saponins from lucerne root were alone found sufficiently toxic to account fully for the activity of the crude extract. Condensed tannins extracted from L. pedunculatus and L. corniculatus had no effect on larval survival when administered at levels equivalent to those present in crude extracts.     

His Own Synthesis: Corn, Edgar Anderson, and Evolutionary Theory in the 1940s

Tracing the contributions of Edgar Anderson (1897--1969) of the Missouri Botanical Garden to the important discussions in evolutionary biology in the 1940s, this paper argues that Anderson turned to corn research rather than play a more prominent role in what is now known as the Evolutionary Synthesis. His biosystematic studies of Iris and Tradescantia in the 1930s reflected such Synthesis concerns as the species question and population thinking. He shared the 1941 Jesup Lectures with Ernst Mayr. But rather than preparing his lectures as a potentially key text in the Synthesis, Anderson began researching Zea mays -- its taxonomy, its origin, and its agronomic role. In this study, Anderson drew on the disciplines of taxonomy, morphology, genetics, geography, anthropology, archaeology, and agronomy among others in his own creative synthesis. Though his maize research in the 1940s represented the most sustained work of his career, Anderson was also drawn in many directions during his professional life. For example, he enjoyed teaching, working with amateurs, and popular writing. This revised version was published online in July 2006 with corrections to the Cover Date.     

Kultursubstrate für den Gartenbau,besonders in Deutschland: — Ein kritischer Überblick

Summary During the past four decades plant substrates have been developed, which have tended to replace the usual methods of cultivation of soil under glass and plastic, more and more, making it independent from local soil conditions and rendering better plant growth. With these substrates soil-borne plant diseases can be eliminated and water- and nutrient supply will be improved. Substrates for common use are characterized by low bulk density, big pore space, good pore space distribution, sufficient adsorption and buffering capacity, favourable water and nutrient supply and a slightly acid soil reaction (pH). The substrates should be free from weed and pathogenic agents. If water and nutrient supply are adapted to the requirements of the cultivated plant, unbuffered substrates such as stonewool and plastic foam can also be well suited and even be advantageous as long as they guarantee sufficient macro pore space (air capacity) under conditions of water saturation. This paper attempts to give a view on the possibilities and aims of the use of plant substrates. It deals furthermore with production, properties, use and control of modern plant substrates. Aus Raumgründen sind nur solche Ver?ffentlichungen aufgeführt, die die bisherige Entwicklung belegen oder als Erg?nzung zum Gesagten wertvoll erschienen.