Rhizobium Lupini Research Articles

THE INDOLE-3-ACETIC ACID OXIDASE OF LUPINUS LUTEUS L. II. A QUANTITATIVE COMPARISON OF THE ACTIVITY OF THIS ENZYME IN ROOT NODULES AND ROOTS

The activity was determined of the various enzyme fractions obtained during ammonium sulphate precipitation and gel filtration of the IAA-oxidase present in root nodules and roots of Lupinus luteus L. Comparison of these activities on a protein basis showed that IAA degradation was lower in root nodules than in roots. Several indications were obtained that phenols were present in all of the enzyme fractions and had an inhibitory effect on the enzyme activity. The possible role of phenols in the regulation of IAA-oxidase activity in lupine is discussed. Rhizobium lupini was isolated from the root nodules, and cell-free enzyme preparations of these bacteria oxidized IAA. The results obtained with cell-free enzyme preparations of bacteroids did not, however, prove conclusively that the bacteroids have this activity.

The colonization of host-root and soil by Rhizobia—I. Species and strain differences in the field

Growing-season populations of rhizobia associated with annual host-plant roots and nearby soil were examined in a field soil showing a nodulation problem in the second year after establishment. Rhizobium lupini reached higher populations at a faster rate than R. trifolii. A sharp drop in the population of R. trifolii associated with subterranean clover roots early in the growing season was followed by a recovery to high numbers. No such phenomenon occurred with R. lupini. The numbers of rhizobia under patches of non-nodulated plants in second-year stands were very low, usually <5/g soil, whereas the numbers under healthy plants in problem stands were similar to those under established stands. Differences in the colonization of both root and soil by R. trifolii in the first year were reflected in the second-year nodulation.

Acid and alkaline invertases in roots and nodules of Lupinus angustifolius infected with Rhizobium lupini

Both acid and alkaline invertase activity were found in tips and cortical tissue of Lupinus angustifolius L. roots infected with Rhizobium lupini NZP 2257. Only the alkaline invertase was detected in the nodule cytoplasm. Weak invertase activity found in the bacteroids was probably a contamination from plant invertase. The alkaline invertase activity in the nodule cytoplasm was 250 times that detected in the bacteroids and 8 times that detected in cortical tissue. No intracellular or extracellular invertase was detected in R. lupini cultured in liquid medium containing sucrose.

Electron microscopical characterization of newly isolated Rhizobium lupini bacteriophages.

Eight strains of Rhizobium lupini bacteriophages newly isolated from compost soil were studied in the electron microscope. The phage particles investigated had either long contractile, long non-contractile, or short non-contractile tails. The wedge-shaped appearance of short phage tails is discussed.

The two transfer regions of the Rhizobium lupini conjugation. I. Fertility factor elimination and one way transfer.

The two transfer regions of the Rhizobium lupini conjugation. I. Fertility factor elimination and one way transfer.

Typing of Rhizobium by phages.

Two hundred and thirty strains of Rhizobium trifolii, Rhizobium leguminosarum for pea, vetch, horse bean, and Lathyrus spp., Rhizobium phaseoli and Rhizobium meliloti were subjected to phage typing. On the basis of their sensitivity to phages these strains were divided into three groups: I, II, and III.In group I, consisting of R. trifolii, R. leguminosarum for pea, vetch, and horse bean, and R. phaseoli, 18 phage types were established. Group II included some strains of R. trifolii and R. leguminosarum for pea and vetch. Among them three phage types were distinguished. Group III included R. meliloti strains and one strain of Rhizobium lupini for lupine. In that group 10 phage types were found.

Bdellovibrio bacteriovorus parasitizing Rhizobium in Western Australia.

Summary. Bdellovibrio bacteriovorus strains which parasitize Rhizobium meliloti, R. trifolii, Agrobacterium tumefaciens and A. radiobacter have been found in Western Australian soils. Rhizobium lupini was not lysed by any strain. Some Bdellovibrio cells pass through 0·22 μm membrane filters, whilst the 0·45 μm filters allow several saprophytic soil bacteria to pass. The strength of the medium is shown to be of great importance for the detection or counting of Bdellovibrio cells. The Bdellovibrio strains are capable of destroying large numbers of rhizobia in the laboratory.

Growth rates of Rhizobium trifolii and Rhizobium lupini in sterilized soils

The growth characteristics of Rhizobium trifolii and R. lupini in a sterilized infertile sandy soil were studied at different temperatures. R. trifolii grew at a faster rate than R. lupini at all temperatures up to 30°C. The optimum temperature for growth for both species was found to be approximately 30°. Temperatures higher than 35° were found to be lethal for both species, the cells of R. trifolii being the more sensitive. In a fertile sandy loam the growth rates of both species were improved, the effect being more pronounced with R. lupini. The presence of the appropriate host plants in the sterilized infertile sand resulted in faster growth rates in both species, particularly R. lupini.

Host Influence on the Ultrastructure of Root Nodules of Lupinus luteus and Ornithopus Sativus

SUMMARY: The ultrastructure of Lupinus luteus L. and Ornithopus sativus Brot. root nodules derived from infection by Rhizobium lupini strain D25 was examined. In both cases the associations produced completely effective nodules but their gross morphology was markedly different. Bacteria within the O. sativus nodules were enclosed in groups by a membranous envelope, and the bacteria had electron translucent regions. Bacteria within the L. luteus nodules were enclosed singly and did not exhibit similar electron translucent regions. Starch granules were observed within infected cells of L. luteus but not within uninfected cells; the reverse was observed in O. sativus cells.

Transformation of a strain of Rhizobium lupini.

Transfer of Cysteine-independence. Strain H–13, which is a cysteine-dependent mutant of the prototroph Rhizobium lupini strain H, developed cysteine-independent colonies on treatment with the deoxyribonucleic acid of strain H (Fig. 1).

A new nitrogen-fixing micro-organism producing a red pigment.

WHILE isolating strains of Rhizobium lupini from the nodules of Lupinus luteus grown on the acid sandy soil of the Nyirseg area in north-eastern Hungary, I succeeded in isolating, on a Rhizobium medium, two red micro-organisms. These have been labelled Pr and E.3. They came from places several miles apart. The plants from which the Pr and E.3 strains derived were in a state of fluorescence and conspicuously larger than the surrounding lupins.