scholarly journals Temporal and Spatial Order of Events During the Induction of Cortical Cell Divisions in White Clover by Rhizobium leguminosarum bv. trifolii Inoculation or Localized Cytokinin Addition

2000 ◽  
Vol 13 (6) ◽  
pp. 617-628 ◽  
Author(s):  
Ulrike Mathesius ◽  
Celine Charon ◽  
Barry G. Rolfe ◽  
Adam Kondorosi ◽  
Martin Crespi
Keyword(s):  
White Clover ◽  
Rhizobium Leguminosarum ◽  
Cortical Cell ◽  
Nodule Formation ◽  
Cell Divisions ◽  
Auxin Transport Inhibitor ◽  
Chalcone Synthase Genes ◽  
Nodule Initiation ◽  
Inner Cortex

We examined the timing and location of several early root responses to Rhizobium leguminosarum bv. trifolii infection, compared with a localized addition of cytokinin in white clover, to study the role of cytokinin in early signaling during nodule initiation. Induction of ENOD40 expression by either rhizobia or cytokinin was similar in timing and location and occurred in nodule progenitor cells in the inner cortex. Inoculation of rhizobia in the mature root failed to induce ENOD40 expression and cortical cell divisions (ccd). Nitrate addition at levels repressing nodule formation inhibited ENOD40 induction by rhizobia but not by cytokinin. ENOD40 expression was not induced by auxin, an auxin transport inhibitor, or an ethylene precursor. In contrast to rhizobia, cytokinin addition was not sufficient to induce a modulation of the auxin flow, the induction of specific chalcone synthase genes, and the accumulation of fluorescent compounds associated with nodule initiation. However, cytokinin addition was sufficient for the localized induction of auxin-induced GH3 gene expression and the initiation of ccd. Our results suggest that rhizobia induce cytokinin-mediated events in parallel to changes in auxin-related responses during nodule initiation and support a role of ENOD40 in regulating ccd. We propose a model for the interactions of cytokinin with auxin, ENOD40, flavonoids, and nitrate during nodulation.

scholarly journals Flavonoids Synthesized in Cortical Cells During Nodule Initiation Are Early Developmental Markers in White Clover

1998 ◽  
Vol 11 (12) ◽  
pp. 1223-1232 ◽  
Author(s):  
Ulrike Mathesius ◽  
Cathy Bayliss ◽  
Jeremy J. Weinman ◽  
Helmi R. M. Schlaman ◽  
Herman P. Spaink ◽  
...  
Keyword(s):  
White Clover ◽  
Rhizobium Leguminosarum ◽  
Fluorescence Emission ◽  
Emission Spectra ◽  
Water Soluble ◽  
Nodule Formation ◽  
Post Inoculation ◽  
Flavonoid Pathway ◽  
Nodule Initiation ◽  
Inner Cortex

We examined the site-specific induction of the flavonoid pathway before and during nodule initiation in white clover with transgenic plants, fluorescence microscopy, and microspectrofluorometry to test if flavonoids play a role in nodule organogenesis. A chalcone synthase regulated β-glucuronidase (GUS) transgene (CHS3:gusA) was up-regulated from 3 h post inoculation (p.i.) until cell division (around 40 h p.i.) in inner cortex cells underlying the inoculation site. Intracellular fluorescence occurred in vacuoles of those inner cortex cells from 13 h p.i. until the fluorescent cells divided. Fluorescence emission spectra of contents of individual fluorescing cortex cells were measured in situ and compared with emission spectra of compounds purified from root extracts. The fluorescing compound located in cells of the inner cortex after Rhizobium leguminosarum bv. trifolii infection was identified as a water-soluble derivative of 7,4′-dihydroxyflavone. Nodule primordium cells contained a different fluorescent compound, identified as the isoflavonoid formononetin. CHS3:gusA expression and flavonoid accumulation were only induced in inner cortex cells by a nodulating Rhizo-bium strain and by clover-specific lipo-chitinoligosac-charides, but not by non-nodulating rhizobia. Fluorescence was also induced by compatible rhizobia in other legumes such as alfalfa, pea, and siratro in the cells that participate in nodule initiation. Our results show that fluorescent flavonoids are useful markers in nodule or-ganogenesis in clover and may have direct roles in nodule formation.

scholarly journals Nod Factor-Induced Expression of Leghemoglobin to Study the Mechanism of NH4NO3 Inhibition on Root Hair Deformation

1997 ◽  
Vol 10 (2) ◽  
pp. 215-220 ◽  
Author(s):  
Renze Heidstra ◽  
Gerd Nilsen ◽  
Francisco Martinez-Abarca ◽  
Ab van Kammen ◽  
Ton Bisseling
Keyword(s):  
Gene Expression ◽  
Root Hair ◽  
Rhizobium Leguminosarum ◽  
Cortical Cell ◽  
Brefeldin A ◽  
Marker Genes ◽  
Nodule Formation ◽  
Cdna Clones ◽  
Nod Factor ◽  
Root Hair Deformation

Nod factors secreted by Rhizobium leguminosarum bv. viciae induce root hair deformation, the formation of nodule primordia, and the expression of early nodulin genes in Vicia sativa (vetch). Root hair deformation is induced within 3 h in a small, susceptible zone (±2 mm) of the root. NH4NO3, known to be a potent blocker of nodule formation, inhibits root hair deformation, initial cortical cell divisions, and infection thread formation. To test whether NH4NO3 affects the formation of a component of the Nod factor perception-transduction system, we studied Nod factor-induced gene expression. The differential display technique was used to search for marker genes, which are induced within 1 to 3 h after Nod factor application. Surprisingly, one of the isolated cDNA clones was identified as a leghemoglobin gene (VsLb1), which is induced in vetch roots within 1 h after Nod factor application. By using the drug brefeldin A, it was then shown that VsLb1 activation does not require root hair deformation. The pVsLb1 clone was used as a marker to show that in vetch plants grown in the presence of NH4NO3 Nod factor perception and transduction leading to gene expression are unaffected.

scholarly journals SHORT-ROOT paralogs mediate feedforward regulation of D-type cyclin to promote nodule formation in soybean

2022 ◽  
Vol 119 (3) ◽  
pp. e2108641119
Author(s):  
Chunhua Wang ◽  
Meng Li ◽  
Yang Zhao ◽  
Nengsong Liang ◽  
Haiyang Li ◽  
...  
Keyword(s):  
Cell Division ◽  
Vascular Tissue ◽  
De Novo ◽  
Cortical Cell ◽  
Nodule Formation ◽  
Cytokinin Signaling ◽  
Short Root ◽  
Cell Divisions ◽  
Early Nodulin ◽  
Nodulin Genes

Nitrogen fixation in soybean takes place in root nodules that arise from de novo cell divisions in the root cortex. Although several early nodulin genes have been identified, the mechanism behind the stimulation of cortical cell division during nodulation has not been fully resolved. Here we provide evidence that two paralogs of soybean SHORT-ROOT (GmSHR) play vital roles in soybean nodulation. Expression of GmSHR4 and GmSHR5 (GmSHR4/5) is induced in cortical cells at the beginning of nodulation, when the first cell divisions occur. The expression level of GmSHR4/5 is positively associated with cortical cell division and nodulation. Knockdown of GmSHR5 inhibits cell division in outer cortical layers during nodulation. Knockdown of both paralogs disrupts the cell division throughout the cortex, resulting in poorly organized nodule primordia with delayed vascular tissue formation. GmSHR4/5 function by enhancing cytokinin signaling and activating early nodulin genes. Interestingly, D-type cyclins act downstream of GmSHR4/5, and GmSHR4/5 form a feedforward loop regulating D-type cyclins. Overexpression of D-type cyclins in soybean roots also enhanced nodulation. Collectively, we conclude that the GmSHR4/5-mediated pathway represents a vital module that triggers cytokinin signaling and activates D-type cyclins during nodulation in soybean.

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.

scholarly journals The Role of Non-Coding RNAs in the Regulation of the Proto-Oncogene MYC in Different Types of Cancer

Biomedicines ◽  
2021 ◽  
Vol 9 (8) ◽  
pp. 921
Author(s):  
Ekaterina Mikhailovna Stasevich ◽  
Matvey Mikhailovich Murashko ◽  
Lyudmila Sergeevna Zinevich ◽  
Denis Eriksonovich Demin ◽  
Anton Markovich Schwartz
Keyword(s):  
Malignant Tumors ◽  
Current Data ◽  
Cellular Processes ◽  
Cell Divisions ◽  
Specific Tumor ◽  
Different Types ◽  
Myc Gene ◽  
Non Coding Rnas ◽  
Tumor Types

Alterations in the expression level of the MYC gene are often found in the cells of various malignant tumors. Overexpressed MYC has been shown to stimulate the main processes of oncogenesis: uncontrolled growth, unlimited cell divisions, avoidance of apoptosis and immune response, changes in cellular metabolism, genomic instability, metastasis, and angiogenesis. Thus, controlling the expression of MYC is considered as an approach for targeted cancer treatment. Since c-Myc is also a crucial regulator of many cellular processes in healthy cells, it is necessary to find ways for selective regulation of MYC expression in tumor cells. Many recent studies have demonstrated that non-coding RNAs play an important role in the regulation of the transcription and translation of this gene and some RNAs directly interact with the c-Myc protein, affecting its stability. In this review, we summarize current data on the regulation of MYC by various non-coding RNAs that can potentially be targeted in specific tumor types.

Nitrate reductases and hemoglobins control nitrogen-fixing symbiosis by regulating nitric oxide accumulation

2020 ◽  
Author(s):  
Antoine Berger ◽  
Alexandre Boscari ◽  
Alain Puppo ◽  
Renaud Brouquisse
Keyword(s):  
Nitric Oxide ◽  
Defense Responses ◽  
Nodule Formation ◽  
No Production ◽  
Degradation Pathways ◽  
Atmospheric Nitrogen ◽  
Metabolic Intermediate ◽  
Hypoxic Environment ◽  
Nitrate Reductases

Abstract The interaction between legumes and rhizobia leads to the establishment of a symbiotic relationship between plant and bacteria. This is characterized by the formation of a new organ, the nodule, which facilitates the fixation of atmospheric nitrogen (N2) by nitrogenase through the creation of a hypoxic environment. Nitric oxide (NO) accumulates at each stage of the symbiotic process. NO is involved in defense responses, nodule organogenesis and development, nitrogen fixation metabolism, and senescence induction. During symbiosis, either successively or simultaneously, NO regulates gene expression, modulates enzyme activities, and acts as a metabolic intermediate in energy regeneration processes via phytoglobin-NO respiration and the bacterial denitrification pathway. Due to the transition from normoxia to hypoxia during nodule formation, and the progressive presence of the bacterial partner in the growing nodules, NO production and degradation pathways change during the symbiotic process. This review analyzes the different source and degradation pathways of NO, and highlights the role of nitrate reductases and hemoproteins of both the plant and bacterial partners in the control of NO accumulation.

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