Isolation and properties of antimicrobial substance produced by Sinhorhizobium melilloti from root nodules of Medicago sativa

Abstract Alfalfa plants (Medicago sativa cv. Europe) inoculated with Sinorhizobium meliloti 2011 (formerly Rhizobium meliloti, de Lajudie et al., 1994) were cultivated for 14 days under standardized growth conditions in mineral medium with addition of the heavy metal cadmium or the polycyclic aromatic hydrocarbon fluoranthene. These xenobiotics significantly reduced the numbers of root nodules before any visible damage to the plant could be detected. EC10. EC50, and EC90 (effective concentrations reducing nodulation, shoot and root fresh weight by 10, 50, or 90% compared to the control without pollutant) were calculated. EC50 for cadmium ranged from 5.8 jam (nodulation) to more than 20 μᴍ (root fresh weight). Testing fluoranthene resulted in an EC50 of 2.5 μg cm-2 for nodulation, and EC50 values of more than 35 μg cm-2 for shoot and root biomass production, indicating that the effect parameter nodulation is 10-fold more sensitive than shoot and root fresh weight. With m RNA differential display techniques the effects of both xenobiotics on gene expression in alfalfa root systems were studied. 37 differentially displayed transcripts were detected. Two of them, called DDMs1 and DDMs2, were confirmed by northern hybridization to be down-regulated in the presence of the xenobiotics. The expression of transcript DDMs1 was enhanced in alfalfa control plants inoculated with rhizobia, the transcript level was increased 2.5-3-fold compared to non-inoculated plants. This positive effect of nodulation was suppressed, partly by 35 μg cm-2 fluoranthene and totally by 20 μᴍ cadmium. The decrease in DDMsl transcription was highly affected by the cadmium concentration with an EC50 of 5.9 μᴍ . Compared to nodulation, almost identical EC10, EC50. and EC90 values were found for DDMsl expression. Sequence analysis of DDMsl revealed a significant overall homology (50% identity) to a hypothetical protein from Arabidopsis thaliana with high similarity to a copper transporting ATPase. High levels of transcript DDMs2 were observed in control plants with a 50% decrease in the xenobiotic-treated plants. DDM s2 gave a strong homology (82% identity) to the cytoplasmatic 60S ribosomal protein L18 from Arabidopsis thaliana.

Download Full-text

Co-inoculation of lucerne (Medicago sativa) with an AM fungus and a rhizobium reduces occurrence of spring black stem and leaf spot caused by Phoma medicaginis

Crop and Pasture Science ◽

10.1071/cp18135 ◽

2018 ◽

Vol 69 (9) ◽

pp. 933 ◽

Cited By ~ 9

Author(s):

Ping Gao ◽

Yingde Li ◽

Yane Guo ◽

Tingyu Duan

Keyword(s):

Medicago Sativa ◽

Leaf Spot ◽

Root Nodules ◽

Disease Incidence ◽

Arbuscular Mycorrhizal ◽

Dry Weight ◽

Sinorhizobium Medicae ◽

Phoma Medicaginis ◽

Am Fungus ◽

Serious Disease

Spring black stem and leaf spot of lucerne (alfalfa, Medicago sativa L.), caused by Phoma medicaginis, is an important disease in temperate regions of the world. It is now a serious disease threatening global lucerne production. This experiment was designed to test the combined effects of the arbuscular mycorrhizal (AM) fungus Funneliformis mosseae and the rhizobium Sinorhizobium medicae on growth, nutrient uptake and disease severity in lucerne. The results showed that F. mosseae increased plant phosphorus and nitrogen uptake and plant dry weight, and this beneficial effect was enhanced when in association with S. medicae. Rhizobial and AM fungal effects were mutually promoting; inoculation with AM fungus significantly increased the formation of root nodules, and inoculation with rhizobium increased the percentage of root length colonised by AM fungus (P < 0.05). After infection with P. medicaginis, typical leaf spot symptoms with the lowest disease incidence and disease index occurred on plants that were host to both F. mosseae and S. medicae. Plants with both symbiotic microorganisms had higher activities (concentrations) of phenylalanine ammonia-lyase, chitinase, β-1,3-glucanase, lignin, hydroxyproline-rich glycoprotein and jasmonic acid. Therefore, the tested AM fungus (F. mosseae) and rhizobium (S. medicae) have the potential to reduce damage and yield loss in lucerne from spring black stem and leaf spot caused by P. medicaginis.

Download Full-text

The Alfalfa (Medicago sativa) TDY1 Gene Encodes a Mitogen-Activated Protein Kinase Homolog

Molecular Plant-Microbe Interactions ◽

10.1094/mpmi.1999.12.10.882 ◽

1999 ◽

Vol 12 (10) ◽

pp. 882-893 ◽

Cited By ~ 27

Author(s):

Mark A. Schoenbeck ◽

Deborah A. Samac ◽

Maria Fedorova ◽

Robert G. Gregerson ◽

J. Stephen Gantt ◽

...

Keyword(s):

Protein Kinase ◽

Medicago Sativa ◽

Map Kinases ◽

Root Nodules ◽

Genomic Clone ◽

Mitogen Activated Protein Kinase ◽

Vascular Bundles ◽

Root Tips ◽

Pathogen Invasion ◽

Mitogen Activated Protein

Development of root nodules, specifically induction of cortical cell division for nodule initiation, requires expression of specific genes in the host and microsymbiont. A full-length cDNA clone and the corresponding genomic clone encoding a MAP (mitogen-activated protein) kinase homolog were isolated from alfalfa (Medicago sativa). The genomic clone, TDY1, encodes a 68.9-kDa protein with 47.7% identity to MMK4, a previously characterized MAP kinase homolog from alfalfa. TDY1 is unique among the known plant MAP kinases, primarily due to a 230 amino acid C-terminal domain. The putative activation motif, Thr-Asp-Tyr (TDY), also differs from the previously reported Thr-Glu-Tyr (TEY) motif in plant MAP kinases. TDY1 messages were found predominantly in root nodules, roots, and root tips. Transgenic alfalfa and Medicago truncatula containing a chimeric gene consisting of 1.8 kbp of 5′ flanking sequence of the TDY1 gene fused to the β-glucuronidase (GUS) coding sequence exhibited GUS expression primarily in the nodule parenchyma, meristem, and vascular bundles, root tips, and root vascular bundles. Stem internodes stained intensely in cortical parenchyma, cambial cells, and primary xylem. GUS activity was observed in leaf mesophyll surrounding areas of mechanical wounding and pathogen invasion. The promoter was also active in root tips and apical meristems of transgenic tobacco. Expression patterns suggest a possible role for TDY1 in initiation and development of nodules and roots, and in localized responses to wounding.

Download Full-text

Effects of water stress on enzymes of ammonia assimilation in root nodules of alfalfa (Medicago sativa)

Physiologia Plantarum ◽

10.1111/j.1399-3054.1984.tb05186.x ◽

1984 ◽

Vol 61 (4) ◽

pp. 653-657 ◽

Cited By ~ 8

Author(s):

M. Becana ◽

P. M. Aparicio-Tejo ◽

M. Sanchez-Diaz

Keyword(s):

Water Stress ◽

Medicago Sativa ◽

Root Nodules ◽

Ammonia Assimilation ◽

Enzymes Of Ammonia Assimilation

Download Full-text

Ciprofloxacin Residues in Irrigation Water and Their Effects on Alfalfa (Medicago Sativa) Carbon Fixation, Number of Root Nodules and Root Length

SSRN Electronic Journal ◽

10.2139/ssrn.3967416 ◽

2021 ◽

Author(s):

Franz Vilca ◽

Tatiana Edith Laura Ponce ◽

Oscar Duberly Vera Loayza ◽

Leonardo Vilela Junqueira ◽

Nestor Cahui Galarza ◽

...

Keyword(s):

Medicago Sativa ◽

Irrigation Water ◽

Root Length ◽

Carbon Fixation ◽

Root Nodules

Download Full-text

Diverse bacterial taxa inhabit root nodules of lucerne (Medicago sativa L.) in New Zealand pastoral soils

Plant and Soil ◽

10.1007/s11104-017-3395-6 ◽

2017 ◽

Vol 420 (1-2) ◽

pp. 253-262 ◽

Cited By ~ 7

Author(s):

Kathryn Wigley ◽

Derrick Moot ◽

Steve A Wakelin ◽

Aurelie Laugraud ◽

Celine Blond ◽

...

Keyword(s):

New Zealand ◽

Medicago Sativa ◽

Root Nodules ◽

Medicago Sativa L

Download Full-text

Localization of oleosomes in the root nodules of alfalfa (Medicago sativa)

Canadian Journal of Botany ◽

10.1139/b98-131 ◽

1998 ◽

Vol 76 (8) ◽

pp. 1418-1423 ◽

Cited By ~ 1

Author(s):

A Darryl Martin ◽

Arya K Bal ◽

David B McKenzie

Keyword(s):

Medicago Sativa ◽

Vascular Tissue ◽

Rhizobium Meliloti ◽

Root Nodules ◽

Hexane Extraction ◽

En Bloc ◽

Cortical Cells ◽

Storage Organs ◽

Vascular Parenchyma ◽

Meliloti Strain

Histological studies of rhizobia-induced nodules and spontaneous pseudonodules of alfalfa were undertaken to reveal the distribution pattern of oleosomes. Alfalfa (Medicago sativa L. cv. 'Algonquin') seedlings were inoculated with Rhizobium meliloti (strain Balsac), and grown in controlled conditions. Seedlings were also grown aseptically to obtain spontaneous pseudonodules. Nodule slices were fixed in a paraformaldehyde-glutaraldehyde mixture and processed for embedding in Spurr's medium after OsO4 treatment and en bloc staining, with p-phenylenediamine (pPD) in 70% ethanol, for oleosomes. As a control, hexane extraction of lipids was employed. In pseudonodules, oleosomes were present in the vascular parenchyma, the meristem region and in the five to seven layers of cortical cells adjacent to the vascular tissue. The allocation of energy stored as triacylglycerides, in the form of oleosomes, and starch indicates that pseudonodules are a sink for carbon, possibly functioning as storage organs. In mature nodules, oleosomes were distinguished clearly in nodule parenchyma but were absent in infected cells. Young nodules were devoid of oleosomes. The prevalence of oleosomes in the mature nodules may indicate that the triacylglycerides are stored for overwintering, as alfalfa nodules are known to be perennial. The oleosomes in root nodules of alfalfa do not appear to be directly associated with nitrogen fixation per se.Key words: oleosomes, root nodules, Medicago sativa, Rhizobium, pseudonodules.

Download Full-text