Vicia Hirsuta Research Articles

Host Specific Nodulation of Plants of the Pea Cross-inoculation Group is Influenced by Genes in Fast Growing Rhizobium downstream nodC

Summary Tn5 induced mutants in nodI and nodJ of the Rhizobium leguminosarum biovar viceae Sym plasmid pRL1JI nodulated Vicia sativa and Vicia hirsuta plants slightly delayed. Complementation experiments showed that nodI,J were part of the nodA,B,C transcriptional unit. A Rhizobium strain in which two Sym plasmids were present, almost completely lost the ability to nodulate V sativa plants when nodI,J on both Sym plasmids were inactivated. Several other plants of the pea cross-inoculation group showed a likewise difference in their nodulation response. In addition we investigated the nodulation of Afghanistan peas. R. leguminosarum biovar viceae strains do not nodulate Afghanistan peas. When a Sym plasmid from such a strain was transferred to wild type R. leguminosarum biovar trifolii strains, the resulting strains nodulated Afghanistan peas. We provide evidence for the existence of a new gene, necessary for the nodulation of Afghanistan peas, which is located in the nodA,B,C,I,J operon of R. leguminosarum biovar trifolii strain ANU843.

Promoters in the nodulation region of the Rhizobium leguminosarum Sym plasmid pRL1JI

A region of 16.8 kb of the Sym(biosis) plasmid pRL1JI of Rhizobium leguminosarum, consisting of the established 9.7 kb nodulation region which confers nodulation ability on Vicia hirsuta and a region of 7.1 kb which appeared to be necessary for nodulation on V. sativa and Trifolium subterraneum, was subcloned as fragments of maximally 2.5 kb in a newly developed IncQ transcriptional fusion vector. The expression of these fragments was studied in Rhizobium. One constitutive promoter, pr.nodD, and three plant-exudate inducible promoters were found, namely the known pr.nodA and pr.nodF as well as a new promoter designated pr.nodM. The latter promoters were localized within 114 bp, 330 bp and 630 bp respectively and they regulate the transcription of the operons nodA, B, C, I, J, nodF, E and of an operon of at least 2.5 kb located in the 7.1 kb region. Induction of the three inducible operons required plant exudate and a functional nodD product. The flavanone naringenin could replace plant exudate. Each of the three inducible promoters contained a nod-box. A consensus for the nod-box sequence, based on known sequences, is proposed. The 114 bp fragment which contains pr.nodA activity was used to localize pr.nodA by means of deletion mapping. The fragment which appeared necessary for complete pr.nodA activity is 72 bp in size, contains the complete nod-box and in addition a region of 21 bp downstream of the nod-box, in which the loosely conserved sequence AT(T)AG appears to be important for promoter activity.

Endoplasmic microtubules connect the advancing nucleus to the tip of legume root hairs, but F‐actin is involved in basipetal migration

AbstractA prominent feature of tip growth in filamentous plant cells is that the nucleus often migrates in step with the tip as it extends. We have studied this long‐recognized but unexplained relationship in root hairs of the legume Vicia hirsuta by a variety of microscopic techniques. Using rhodaminyl lysine phallotoxin, and antitubulin antibodies, root hairs are shown to contain axial bundles of F‐actin and a complex microtubular system. To the basal side of the nucleus the microtubules are cortical and net axial but in the region between nucleus and tip the arrangement is more complicated. Electron microscopic thin sections demonstrate that internal bundles of microtubles exist in addition to the plasma membrane‐associated kind. Computerized deblurring of through‐focal series of antitubulin stained hairs clarifies the three‐dimensional organization: bundles of endoplasmic microtubules progress from the nuclear region toward the apical dome where they can be seen to fountain out upon the cortex.The relationship between nucleus and tip can be uncoupled with antimicrotubule herbicides. Time lapse video microscopy shows that these agents cause the nucleus to migrate toward the base. This contrary migration can be inhibited by adding cytochalasin D, which fragments the F‐actin bundles.It is concluded that microtubules connect the nucleus to the tip but that F‐actin is involved in basipetal migration as is known to occur when symbiotic bacteria uncouple the nucleus from the tip.

Nodulation inhibition by Rhizobium leguminosarum multicopy nodABC genes and analysis of early stages of plant infection.

During analysis of early events in the infection and nodulation of Vicia hirsuta roots inoculated with normal and mutant strains of Rhizobium leguminosarum and strains containing cloned nodulation (nod) genes, a number of novel observations were made. (i) Alternating zones of curled and straight root hairs were seen on roots of V. hirsuta inoculated with the wild-type strain of R. leguminosarum. This phasing of root hair curling was not seen if plants were grown under continuous light or continuous dark conditions. (ii) Reduced nodulation and delayed nodule initiation was observed with a strain carrying a Tn5 mutation in the nodE gene. In addition the phased root hair curling was absent, and root hair curling was observed along the length of the root. (iii) The nodABC genes cloned on a multicopy plasmid in a wild-type strain inhibited nodulation but induced a continuous root hair curling response. Those few nodules that eventually formed were found to contain bacteria which had lost the plasmid carrying the nodABC genes. (iv) With a strain of Rhizobium cured of its indigenous symbiotic plasmid, but containing the cloned nodABCDEF genes, continuous root hair curling on V. hirsuta was observed. However, no infection threads were observed, and surprisingly, it did appear that initial stages of nodule development occurred. Observations of thin sections of these early developing nodules indicated that early nodule meristematic divisions may have occurred but that no bacteria were found within the nodules and no infection threads were observed either within the nodule bumps or within any of the root hairs. It was concluded that for normal infections to occur, precise regulation of the nod genes is required and that overexpression of the root hair curling genes inhibits the normal infection process.

Seed survival and seasonal pattern of seedling emergence in some Leguminosae

SUMMARYSeeds of 11 species of Leguminosae were collected, usually in each of 3 years, and mixed with the top 7·5 cm of sterilised soil confined in cylinders sunk in the ground outdoors and cultivated three times yearly. Emergence was recorded for at least 3 yr. Some seedlings of all species emerged soon after sowing but their numbers varied both within and between species, a probable reflection of the percentage of ‘hard’ seeds in the samples. Appreciable numbers of seedlings appeared in the following 3 yr but few seeds remained viable and dormant after 5 yr. The annual weed Vicia hirsuta was an exception, with an average of 11% of the seeds sown still viable at this time. Most seedlings of Lotus corniculatus, Medicago lupulina, Melilotus altissima, Trifolium repens and Vicia cracca emerged in spring, V. cracca rather later than the others. In contrast, maximum emergence of Trifolium arvense, T. campestre and T. dubium took place from June to September. Limited data indicated a similar pattern for T. striatum and Lathyrus pratensis. Seedlings of Vicia hirsuta emerged from October to May but scarcely at all in summer. Although variation in the percentage of hard seeds influenced the extent of immediate germination and seed persistence, the seasonal patterns in seedling emergence of most species were found to be very consistent.

Rhizobium leguminosarum genes involved in early stages of nodulation.

Nodulation genes from Rhizobium leguminosarum have been subcloned and transferred to a strain of R. phaseoli with its symbiotic plasmid deleted (and therefore its nodulation and nitrogen fixation genes). Normal infection and nodule development occurred when these strains were added to the roots of Pisum sativum (peas) and Vicia hirsuta. The pea nodules were examined by electron microscopy; bacteroid forms were seen surrounded by peribacteroid membranes and using immuno-gold labelling it was shown that the nodule cells contained leghaemoglobin within the cytoplasm. By subcloning and analysing the nodulation region it was found that a small (3.2 X 10(3) bases) fragment of DNA contained three genes involved in root hair curling, the first observed step in the interaction between R. leguminosarum and the root hair cells of these legumes.

Development and structure of ineffective nodules in some leguminous weeds

The structure and development of the ineffective nodules ofTephrosia apollinea, Trigonella polycerata, Vicia hirsuta andV. sativa have been studied and discussed.

Purification and characterization of lectins from Vicia hirsuta

The presence of three lectins in the seeds of Vicia hirsuta (L.) S. F. Gray, a wild‐growing vetch, was shown. The main lectin was purified to homogeneity by buffer extraction, ammonium sulfate precipitation, affinity chromatography on Sephadex G‐100 and isoelectric focusing in granulated gel. By chromatofocusing instead of isoelectric focusing the yield was increased 5‐fold. The lectin has a pi of 6.4. It is composed of large β‐subunits (Mr 19.200) and small α‐subunits (Mr 12.800) in a 1:1 ratio. The subunits can be separated on Sephadex G‐75 when equilibrated with 6 M guanidine‐HCl. The amino acid composition of the two different subunits has been determined. No sulfur‐containing amino acids are present. The lectin resembles the lectins from legumes from the same cross‐inoculation group, i.e. Lens culinaris, Lens esculenta, Pisum satiyum and several Vicia spp. by the same type of sugar specificity and amino acid composition.

Karyotype Analysis inVicia Hirsuta(L.) S. F. Gray andVicia MeyeriBoiss.

SUMMARYResults of a preliminary karyological study of bulgarian populations of Vicia hirsuta and V. meyeri are reported. Diploid chromosome number 2n = 2x=14 was observed in all populations studied. The karyotypes of the two species are characterized by quite similar chromosome types and a high level of symmetry. Along with that, certain differences are evident. The karyotype of V. meyeri consists of slightly longer chromosomes. Most obvious difference is observed in the SAT-chromosome pair morphology; in V. hirsuta it possesses a smaller satellite attached to the short arm; in V. meyeri the satellite is considerably larger than that in V. hirsuta. It is equal in length to the shorter arm, from which it is separated by a secondary constriction.

Small leguminosae as test plants for nodulation of Rhizobium leguminosarum and other rhizobia and agrobacteria harbouring a leguminosarum sym-plasmid

Small plants from the pea cross-inoculation group were selected for rapid nodulation on agar in test tubes. Plants from the genus Vicia were best; strains of the species hirsuta, tetrasperma, sativa and lathyroides nodulated respectively 4, 5, 4 and 7 days after inoculation with Rhizobium leguminosarum RBL 1. Rapid nodulation, visibility of the root system and in situ acetylene reduction makes the culture tube system ideal for genetic studies of Rh. leguminosarum. A number of bacteria including Agrobacterium tumefaciens containing a Sym-plasmid from Rh. leguminosarum formed root nodules. A Vicia sativa strain formed thick and short roots (Tsr) when inoculated with a bacterium harbouring a Sym-plasmid from Rh. leguminosarum. Crown gall formation could also be investigated by wounding of axenic Vicia hirsuta in test tubes.

Intérêt de la platine goniométrique pour l'étude d'analogues biologiques de cristaux-liquides à structure cholestérique

Click to increase image sizeClick to decrease image sizeSummaryA transmission electron microscope fitted with a goniometric stage provides the opportunity for studying the handedness or chirality of the fibers in biological analogues of liquid-crystals of the cholesteric type. Depending on the texture of the liquid-crystal one may use the phenomenon of inversion of arcs or the shift of dotted areas. These two phenomenons appear on the screen of the electron-microscope when the sections containing the twisted materials are suitably tilted.From the study of the nucleoids in bacteroids of slow-growing Rhizobium we can demonstrate that bacterial nucleoids in general are biological analogues of liquid-crystals of the cholesteric type in which the DNA fibers show a left handedness.Some cells of Vicia tetrasperma and Vicia hirsuta root nodules contain in their vacuoles many birefringent inclusions which are identical to a cholesteric mesomorph having a λ2+ texture in the terminology used by KLEMAN and FRIEDEL. With the preceding technique it appears that the fibers in the inclusions have a right handedness. This type of handedness is probably the first one reported in cholesterics.

Deoxyribonucleic Acid Homology Among Strains of Rhizobium trifolii and Related Species

Deoxyribonucleic acid homologies were determined among 27 strains of Rhizobium trifolii, 4 strains of Rhizobium leguminosarum, and 4 strains of Rhizobium phaseoli. Results from related strains indicated that deoxyribonucleic acid homologies correlate with serological relationships and that the ability to form nodules on legume roots can be lost without a detectable change in homology with an independent reference strain. All rhizobia which effectively nodulated Trifolium repens, Trifolium subterraneum, Trifolium ambiguum, and Vicia hirsuta formed one population with an average relatedness of 70% (range, 49 to 94%) and a ▵Tm(e) of 0.0 to 11.8°C with respect to reference strains capable of nodulating the first two clover species. Two strains from African Trifolium species and two strains from a northern Asiatic species were less closely related. The average relatedness of strains from Phaseolus vulgaris to clover rhizobia was 46% (range, 37 to 50%), and the Tm(e) was 6.5 to 11.8°C. Taxonomic revisions consistent with these observations are discussed. It is proposed that R. trifolii and R. leguminosarum should be combined under the name which has priority, Rhizobium leguminosarum Frank. Within this species various biovars should be designated according to plant specificity. R. phaseoli should be retained at present as a separate species and examined in more detail. The results are discussed in relation to proposed genetic bases for plant specificity.

Phosphate Uptake and its Incorporation in Some Crop Plants and their Associated Weeds

Phosphate uptake rate and its incorporation into the foliar organ of four crop plants, viz. pearl millet, pigeon pea, wheat, and gram, and six weeds Cyperus rotundus, Chenopodium album, Asphodelus tenuifolius, Anagallis arvensis, Vicia hirsuta, and Euphorbia dracunculoides were studied with the help of P32. It is concluded that phosphate uptake and its incorporation into the leaves depend on age and species of plant. Rate of phosphate uptake increases in all species as they proceed towards maturity but the incorporation of phosphate is maximum during early stages of growth