Newly featured infection events in a supernodulating soybean mutant SS2-2 by Bradyrhizobium japonicum

2006 ◽  
Vol 52 (4) ◽  
pp. 328-335 ◽  
Author(s):  
Puji Lestari ◽  
Kyujung Van ◽  
Moon Young Kim ◽  
Byun-Woo Lee ◽  
Suk-Ha Lee
Keyword(s):  
Glycine Max ◽  
Bradyrhizobium Japonicum ◽  
Cortical Cell ◽  
Root Hairs ◽  
Nodule Development ◽  
Nodule Formation ◽  
Vascular Bundles ◽  
Wild Type ◽  
In The Wild ◽  
Supernodulating Mutant

Supernodulating soybean (Glycine max L. Merr.) mutant SS2-2 and its wild-type counterpart, Sinpaldalkong 2, were examined for the microstructural events associated with nodule formation and development. SS2-2 produced a substantially higher percentage of curled root hairs than the wild type, especially at 14 days after inoculation with Bradyrhizobium japonicum. In addition, there was new evidence that in SS2-2, B. japonicum also entered through fissures created by the emerging adventitious root primordia. Early steps of nodule ontogeny were faster in SS2-2, and continued development of initiated nodules was more frequent and occurred at a higher frequency than in the wild type. These data suggest that the early expression of autoregulation is facilitated by decreasing the speed of cortical cell development, leading to the subsequent termination of less-developed nodules. The nodules of SS2-2 developed into spherical nodules like those formed on the wild type. In both the wild type and supernodulating mutant, vascular bundles bifurcate from root stele and branch off in the nodule cortex to surround the central infected zone. These findings indicate that SS2-2 has complete endosymbiosis and forms completely developed nodule vascular bundles like the wild type, but that the speed of nodule ontogeny differs between the wild type and SS2-2. Thus, SS2-2 has a novel symbiotic phenotype with regard to nodule organogenesis.Key words: Bradyrhizobium japonicum, early nodule development, Glycine max, root hair curling, supernodulation.

The nitrate-tolerant symbiosis of Glycine max (L.) Merr. nts382 and Bradyrhizobium japonicum is also tolerant of ammonium

2000 ◽  
Vol 77 (10) ◽  
pp. 1432-1438
Author(s):  
J Kevin Vessey ◽  
Bert Luit
Keyword(s):  
Glycine Max ◽  
Bradyrhizobium Japonicum ◽  
Continuous Flow ◽  
Dry Weight ◽  
Hydroponic Culture ◽  
Wild Type ◽  
Whole Plant ◽  
In The Wild ◽  
Glycine Max L ◽  
Wild Type Parent

Previously, we have shown that the Glycine max (L.) Merr. -Bradyrhizobium japonicum symbiosis is very sensitive to inhibition by NH4+. The current study addresses whether the supernodulating soybean mutant, nts382, which is known to be tolerant of NO3-, is also tolerant of NH4+. The nts382 mutant and its wild-type parent, Bragg, were grown in continuous-flow hydroponic culture in the presence of 0, 0.25, 0.5, or 1.0 mM 15N-enriched NH4+. Plants were harvested at 14, 21, and 28 days after inoculation. Both cultivars had the highest dry weight (DW) at each harvest date when grown on 0.25 mM NH4+. At 0.25 mM NH4+, whole plant DW increased by 5.3- and 3.2-fold in Bragg and nts382, respectively, compared with the 0.0 mM NH4+ control by the end of the experiment. As expected, whole-plant nodulation (nodules per plant), DW-specific nodulation (nodules per gram root dry weight), and nodule DW were severely inhibited in Bragg at all levels of NH4+. However, in nts382, whole-plant nodulation was not affected by NH4+ treatment, and nodule DW increased by as much as fivefold. Whereas DW-specific nodulation decreased by 94% in Bragg, this parameter decreased by only 52% in the nts382 mutant. Likewise, while the nitrogen derived from the atmosphere decreased by approximately 40% in NH4+-supplied Bragg, it increased 2.8-fold at 0.25 and 0.5 mM NH4+ in nts382. This study demonstrates that both nodulation and N2 fixation in nts382 are more tolerant of NH4+ than in the wild-type Bragg.

Effects of a Nod-factor-overproducing strain of Sinorhizobium meliloti on the expression of the ENOD40 gene in Melilotus alba

2002 ◽  
Vol 80 (9) ◽  
pp. 907-915 ◽  
Author(s):  
Walter F Giordano ◽  
Michelle R Lum ◽  
Ann M Hirsch
Keyword(s):  
Lateral Root ◽  
Sinorhizobium Meliloti ◽  
Cortical Cell ◽  
Host Cells ◽  
Nodule Development ◽  
Nodule Formation ◽  
Additional Increase ◽  
Nod Factor ◽  
Melilotus Alba ◽  
Different Strains

We have initiated studies on the molecular biology and genetics of white sweetclover (Melilotus alba Desr.) and its responses to inoculation with the nitrogen-fixing symbiont Sinorhizobium meliloti. Early nodulin genes such as ENOD40 serve as markers for the transition from root to nodule development even before visible stages of nodule formation are evident. Using Northern blot analysis, we found that the ENOD40 gene was expressed within 6 h after inoculation with two different strains of S. meliloti, one of which overproduces symbiotic Nod factors. Inoculation with this strain resulted in an additional increase in ENOD40 gene expression over a typical wild-type S. meliloti strain. Moreover, the increase in mRNA brought about by the Nod-factor-overproducing strain 24 h after inoculation was correlated with lateral root formation by using whole-mount in situ hybridization to localize ENOD40 transcripts in lateral root meristems and by counting lateral root initiation sites. Cortical cell divisions were not detected. We also found that nodulation occurred more rapidly on white sweetclover in response to the Nod-factor-overproducing strain, but ultimately there was no difference in nodulation efficiency in terms of nodule number or the number of roots nodulated by the two strains. Also, the two strains could effectively co-colonize the host when inoculated together, although a few host cells were occupied by both strains.Key words: ENOD40, Nod factor, Melilotus, Sinorhizobium, symbiosis.

INFLUENCE OF SINGLE STRAINS AND A COMMERCIAL MIXTURE OF Bradyrhizobium japonicum ON GROWTH, NITROGEN ACCUMULATION AND NODULATION OF TWO EARLY-MATURING SOYBEAN CULTIVARS

1988 ◽  
Vol 68 (2) ◽  
pp. 411-418 ◽  
Author(s):  
L. D. BAILEY
Keyword(s):  
Glycine Max ◽  
Soil Temperature ◽  
Bradyrhizobium Japonicum ◽  
Nodule Formation ◽  
Growth Stages ◽  
Nitrogen Accumulation ◽  
Plant Nitrogen ◽  
Commercial Mixture ◽  
Early Maturing ◽  
Glycine Max L

Seven single strains and a commercial mixture of Bradyrhizobium japonicum were evaluated in association with two early-maturing Canadian soybean (Glycine max (L.) Merrill) cultivars, Maple Presto and Maple Amber. Inoculated and uninoculated plants were grown in pails outdoors. Soil temperature at 15 cm depth was monitored throughout the experiment. At the V2, V3, R2 and R4 growth stages, whole plants were removed from the pails. Nodules were counted and weighed; roots and tops were separated, weighed and analyzed for total nitrogen. Bradyrhizobium japonicum strains 61A148, 61A196, 61A194 and 61A155 were similar in effectiveness, but superior to strains 61A124a, 61A118b, 61A101c and the commercial mixture in earliness of nodule formation, number and weight of nodules per plant, and in promoting greater root and top growth and plant nitrogen accumulation. There were indications that soil temperature may have affected nodulation. Maple Amber showed the greater potential for symbiotic nitrogen fixation. This cultivar supported earlier nodulation, had a greater number of nodules, accumulated more nitrogen in the tops and roots and had greater growth than Maple Presto.Key words: Soybean, Glycine max (L.) Merrill, soil temperature, soybean growth stages, Bradyrhizobium, nodulation

Curled root hairs are a site of entry for Bradyrhizobium infecting hydroponically grown soybean plants with mature root systems

1988 ◽  
Vol 66 (4) ◽  
pp. 683-686 ◽  
Author(s):  
Jeanne M. L. Selker ◽  
John Imsande ◽  
Eldon H. Newcomb
Keyword(s):  
Glycine Max ◽  
Root Hair ◽  
Bradyrhizobium Japonicum ◽  
Root Hairs ◽  
Root Systems ◽  
Glycine Max L ◽  
Soybean Plants ◽  
A Site ◽  
Hydroponically Grown ◽  
Mature Root

Early emergent nodules on roots of hydroponically grown soybean plants (Glycine max (L.) Merr.) were sectioned serially to locate the site of infection by Bradyrhizobium japonicum. The plants had been inoculated only after their root systems had produced numerous higher order branches. The hydroponic solutions contained all required nutrients, including either a suboptimal concentration of nitrate (0.5 mM) or an excess of nitrate (4.0 mM). In all six nodules examined, three with suboptimal nitrate and three with excess nitrate, we found a centrally located root hair containing an infection thread. We conclude that mature root systems of soybean grown in aqueous culture can undergo infection through root hairs in the way that is typical of young seedlings grown either in pots of vermiculite or pouches.

scholarly journals Morphogenesis of root nodules in white clover. II. The effect of mutation in genes nod IJ of the microsymbiont upon the nodule structure

2014 ◽  
Vol 67 (1) ◽  
pp. 5-22
Author(s):  
Barbara Łotocka ◽  
Joanna Kopcińska ◽  
Władysław Golinowski
Keyword(s):  
White Clover ◽  
Rhizobium Leguminosarum ◽  
Root Nodules ◽  
Single Cells ◽  
Wild Strain ◽  
Root Hairs ◽  
Nodule Development ◽  
Wild Type ◽  
Delayed Reaction ◽  
Infection Threads

Morphogenesis of ineffective root nodules initiated on the roots of white clover 'Astra' by the <em>Rhizobium leguminosarum</em> biovar. <em>trifolii</em> strains ANU261 (Tn5 insertion in nod 1 gene) and ANU262 (Tn5 insertion in nod J gene) was investigated. Following changes were observed, as compared to the wild-type nodulation: the exaggerated, not delayed reaction of root hairs; the delay in nodulation with the number of nodules the same as in plants inoculated with a wild strain; the formation and organization of the nodule primordium not changed in comparison with the wild-type nodules; infection threads abnormally branched and diffusing with bacteria deprived of light zone and enriched with storage material; infected cells of bacteroidal tissue abnormally strongly osmiophilic and only slightly vacuolated; symbiosomes with very narrowed peribacteroidal space, subject to premature degradation; abnormal accumulation of starch in the nodule tissues; nodule development blocked at the stage of laterally situated meristem and single nodule bundle; inhibition of divisions in the meristem and vacuolation of its cells; the appearance of single cells with colonies of saprophytic rhizobia embedded in the fibrillar matrix in the old, degraded regions of the bacteroidal tissue.

A rice heterochronic mutant, mori1, is defective in the juvenile-adult phase change

Development ◽  
2002 ◽  
Vol 129 (1) ◽  
pp. 265-273 ◽  
Author(s):  
Kazumi Asai ◽  
Namiko Satoh ◽  
Haruto Sasaki ◽  
Hikaru Satoh ◽  
Yasuo Nagato
Keyword(s):  
Phase Change ◽  
Structural Characteristics ◽  
Day Treatment ◽  
Vascular Bundles ◽  
Wild Type ◽  
Remarkable Feature ◽  
Juvenile Phase ◽  
Shoot Architecture ◽  
Adult Phase ◽  
In The Wild

We have identified five recessive allelic mutations, mori1-1 to mori1-5, which drastically modify the shoot architecture of rice. The most remarkable feature of mori1 plants is a rapid production of small leaves and short branches. The mori1 plants are about 5 cm in height even 7 months after sowing. No reproductive growth was attained in mori1 plants even if inductive short-day treatment was applied. Leaves of mori1 at any position were very small and the size and shape were comparable to those of the wild-type 2nd leaf. The stem of mori1 7 months after sowing did not differentiate node and internode and had randomly oriented vascular bundles, which were characteristic of the basal part of the wild-type stem where 2nd and 3rd leaves were inserted. These structural characteristics indicate that mori1 maintains the 2nd-leaf stage (juvenile phase) of the wild type. The short plastochron and high cell division activity in the shoot apical meristem further confirmed the juvenility of mori1, corresponding to the 2nd-leaf-differentiation stage in the wild-type embryo. Furthermore, the apparent photosynthetic rate in mori1 leaves was low as in the wild-type 2nd leaf. Thus, mori1 is a heterochronic mutation that suppresses the induction of adult phase and the termination of the juvenile phase. Therefore, MORI1 plays an important role in the juvenile-adult phase change. The importance of heterochronic mutations in modifying shoot architecture is discussed.

scholarly journals Iron-Dependent Cytochrome c1 Expression Is Mediated by the Status of Heme in Bradyrhizobium japonicum

2005 ◽  
Vol 187 (15) ◽  
pp. 5084-5089 ◽  
Author(s):  
Tao Gao ◽  
Mark R. O'Brian
Keyword(s):  
Bradyrhizobium Japonicum ◽  
Aminolevulinic Acid ◽  
Iron Status ◽  
Covalent Binding ◽  
Dependent Manner ◽  
Wild Type ◽  
Prosthetic Group ◽  
Protein Levels ◽  
Genes Encoding ◽  
In The Wild

ABSTRACT The heme prosthetic group of heme proteins contains iron, which can be a limiting nutrient. Here, we show that cytochrome c 1 protein from Bradyrhizobium japonicum was strongly affected by the iron status, with low expression in cells grown under iron limitation. This control was not affected in mutants encoding the iron regulator Irr or Fur. Furthermore, cytochrome c 1 mRNA was not influenced by the iron status, suggesting control at a posttranscriptional step. Cytochrome c 1 protein levels were very low in mutants defective in the genes encoding δ-aminolevulinic acid (ALA) synthase and ferrochelatase, enzymes that catalyze the first and final steps of the heme biosynthetic pathway, respectively. Iron-dependent cytochrome c 1 expression was restored in the ALA synthase mutant by supplementation of the medium with the heme precursor ALA. Supplementation with heme resulted in high levels of cytochrome c 1 protein in the wild type and in both mutants, but expression was no longer iron dependent. Cytochrome c 1 is synthesized as a protein precursor fused with cytochrome b. A plasmid-borne construct encoding only cytochrome c 1 was expressed in an iron- and heme-dependent manner similar to that of the wild-type gene, indicating that control by those effectors is not linked to posttranslational processing of the fusion protein. Mutation of the cytochrome c 1 cysteines involved in covalent binding to heme nearly abolished immunodetectable protein. Thus, defects in heme synthesis or heme binding abrogate cytochrome c 1 accumulation, apparently due to protein degradation. We suggest that iron-dependent cytochrome c 1 expression is mediated by heme availability for heme protein formation

scholarly journals Transcription Profiling of Soybean Nodulation by Bradyrhizobium japonicum

2008 ◽  
Vol 21 (5) ◽  
pp. 631-645 ◽  
Author(s):  
Laurent Brechenmacher ◽  
Moon-Young Kim ◽  
Marisol Benitez ◽  
Min Li ◽  
Trupti Joshi ◽  
...  
Keyword(s):  
Nitrogen Fixation ◽  
Bradyrhizobium Japonicum ◽  
Root Nodules ◽  
Expression Patterns ◽  
Root Hairs ◽  
Defense Responses ◽  
Nodule Development ◽  
Plant Defense Responses ◽  
Polymerase Chain ◽  
High Level

Legumes interact with nodulating bacteria that convert atmospheric nitrogen into ammonia for plant use. This nitrogen fixation takes place within root nodules that form after infection of root hairs by compatible rhizobia. Using cDNA microarrays, we monitored gene expression in soybean (Glycine max) inoculated with the nodulating bacterium Bradyrhizobium japonicum 4, 8, and 16 days after inoculation, timepoints that coincide with nodule development and the onset of nitrogen fixation. This experiment identified several thousand genes that were differentially expressed in response to B. japonicum inoculation. Expression of 27 genes was analyzed by quantitative reverse transcriptase-polymerase chain reaction, and their expression patterns mimicked the microarray results, confirming integrity of analyses. The microarray results suggest that B. japonicum reduces plant defense responses during nodule development. In addition, the data revealed a high level of regulatory complexity (transcriptional, post-transcriptional, translational, post-translational) that is likely essential for development of the symbiosis and adjustment to an altered nutritional status.

scholarly journals Spontaneous Root-Nodule Formation in the Model Legume Lotus japonicus: A Novel Class of Mutants Nodulates in the Absence of Rhizobia

2006 ◽  
Vol 19 (4) ◽  
pp. 373-382 ◽  
Author(s):  
Leïla Tirichine ◽  
Euan K. James ◽  
Niels Sandal ◽  
Jens Stougaard
Keyword(s):  
Root Nodule ◽  
Lotus Japonicus ◽  
Nodule Development ◽  
Nodule Formation ◽  
Wild Type ◽  
Model Legume ◽  
Isolation And Characterization ◽  
Mutant Lines ◽  
Spontaneous Nodules

Root-nodule development in legumes is an inducible developmental process initially triggered by perception of lipochitin-oligosaccharide signals secreted by the bacterial microsymbiont. In nature, rhizobial colonization and invasion of the legume root is therefore a prerequisite for formation of nitrogen-fixing root nodules. Here, we report isolation and characterization of chemically induced spontaneously nodulating mutants in a model legume amenable to molecular genetics. Six mutant lines of Lotus japonicus were identified in a screen for spontaneous nodule development under axenic conditions, i.e., in the absence of rhizobia. Spontaneous nodules do not contain rhizobia, bacteroids, or infection threads. Phenotypically, they resemble ineffective white nodules formed by some bacterial mutants on wild-type plants or certain plant mutants inoculated with wild-type Mesorhizobium loti. Spontaneous nodules formed on mutant lines show the ontogeny and characteristic histological features described for rhizobia-induced nodules on wild-type plants. Physiological responses to nitrate and ethylene are also maintained, as elevated levels inhibit spontaneous nodulation. Activation of the nodule developmental program in spontaneous nodules was shown for the early nodulin genes Enod2 and Nin, which are both upregulated in spontaneous nodules as well as in rhizobial nodules. Both monogenic recessive and dominant spontaneous nodule formation (snf) mutations were isolated in this mutant screen, and map positions were determined for three loci. We suggest that future molecular characterization of these mutants will identify key plant determinants involved in regulating nodulation and provide new insight into plant organ development.

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