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

2018 ◽  
Vol 69 (9) ◽  
pp. 933 ◽  
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.

Assessing resistance to spring black stem and leaf spot of alfalfa caused by Phoma spp.

2004 ◽  
Vol 84 (1) ◽  
pp. 311-317 ◽  
Author(s):  
H. Wang ◽  
S. F. Hwang ◽  
K. F. Chang ◽  
B. D. Gossen ◽  
G. D. Turnbull ◽  
...  
Keyword(s):  
Medicago Sativa ◽  
Leaf Spot ◽  
Similar Pattern ◽  
Disease Incidence ◽  
Field Trials ◽  
Disease Reaction ◽  
Detached Leaf ◽  
Controlled Conditions ◽  
Detached Leaves ◽  
Phoma Sclerotioides

The disease reaction of alfalfa (Medicago sativa) cultivars to spring black stem was evaluated in field trials and greenhouse experiments. In field trials, differences in cultivar reaction to leaf spot (predominantly spring black stem) were observed in 9 of 16 station years. The reaction of certain cultivars was consistent across most trials, but other cultivars were quite variable. Under controlled conditions, one isolate each of Phoma sclerotioides and P. exigua produced symptoms on alfalfa leaves that were similar to those caused by P. medicaginis. These results indicate that P. medicaginis is not the only pathogen responsible for symptoms of spring black stem on alfalfa in the prairie region. In a detached-leaf study, one isolate each of P. medicaginis, P. sclerotioides and P. exigua produced leaf lesions on all 18 alfalfa cultivars assessed. Disease incidence in Absolute, Algonquin, Pickseed 3006 and Anik (M. sativa subsp. falcata) was lower than in 630 and AC Blue J. Inoculation of eight selected cultivars using a range of spore concentrations under controlled conditions showed a similar pattern; all three isolates produced leaf lesions on all eight cultivars. Ino culation with conidial suspensions of P. medicaginis resulted in a lower disease incidence on Absolute than on Beaver. Key words: Medicago sativa, Medicago sativa subsp. falcata, Phoma medicaginis, P. sclerotioides, P. exigua, detached leaves.

scholarly journals Effect of Arbuscular Mycorrhizal Fungi on Growth and Antioxidant Activity in Gmelina arborea Roxb. under Salt Stress Condition

2011 ◽  
Vol 3 (4) ◽  
pp. 71-78 ◽  
Author(s):  
Mayura Prakash DUDHANE ◽  
Mahesh Yashwant BORDE ◽  
Paramjit Kaur JITE
Keyword(s):  
Salt Stress ◽  
Tree Species ◽  
Mycorrhizal Fungi ◽  
Stress Condition ◽  
Arbuscular Mycorrhizal ◽  
Dry Weight ◽  
Gmelina Arborea ◽  
Salt Stress Condition ◽  
Am Fungus ◽  
Treated Plant

Gmelina arborea Roxb. is medicinally and economically important tree species were selected for study. An experiment was conducted to determine the influence of arbuscular mycorrhizal (AM) fungus Glomus fasciculatum on salt stress tolerance of tree species Gmelina arborea. Mycorrhizal and nonmycorrhizal seedlings were treated with 100 mM and 200 mM concentration of NaCl. G. fasciculatum treated plant showed increase in fresh and dry weight, greater percentage of mycorrhizal colonization, higher accumulation of proline and chlorophyll content with increasing levels of salinity. G. fasciculatum colonization significantly increased tolerance of salinity, acid phosphatases, and Proline content and also antioxidant enzymes like peroxidase, catalase and superoxide dismutase at all levels of salinity treatments of Gmelina plants in comparison with non-mycorrhizal salinity treated plants. These results demonstrate that AM fungus (G. fasciculatum) is very effective in strengthening the tolerance of Gmelina arborea grown in arid and semi arid areas.

A COMPARISON OF SAMPLING METHODS FOR SURVEYING ALFALFA FOLIAGE DISEASES

1977 ◽  
Vol 57 (4) ◽  
pp. 1091-1097 ◽  
Author(s):  
P. K. BASU ◽  
C. S. LIN ◽  
M. R. BINNS
Keyword(s):  
Medicago Sativa ◽  
Downy Mildew ◽  
Leaf Spot ◽  
Sampling Methods ◽  
Disease Incidence ◽  
Sampling Area ◽  
Stemphylium Botryosum ◽  
Entire Field ◽  
Medicago Sativa L ◽  
Eastern Ontario

Two surveys of eastern Ontario alfalfa (Medicago sativa L.) fields were conducted in 1973 and 1974 to study the effects of the size of sampling area, the pattern of sampling paths, and the spread among sampling sites in relation to the incidence of common leaf spot (Pseudopeziza medicaginis (Lib.) Sacc.), Stemphylium leaf spot (Stemphylium botryosum Wallr.), and downy mildew (Peronospora trifoliorum de Bary). Results of the 1973 survey of 17 fields by three methods indicated that sampling along a 90-m diagonal of a square area of size 4,047 m2 (1 acre) within a quadrant of a field was adequate when disease incidence was either below 20 or above 80%; however, when disease incidence was intermediate (20–80%), sampling along a W-shaped path covering the entire field was more appropriate. Results of the 1974 survey of 60 fields suggested that the total number of sampling sites per field could be reduced from 40 to 15 without reducing precision, provided they were well distributed throughout the field.

scholarly journals Impact of Crude Oil on Functional Groups of Culturable Bacteria and Colonization of Symbiotic Microorganisms in the Clitoria-Brachiaria Rhizosphere Grown in Mesocosms

2019 ◽  
Vol 24 (2) ◽  
pp. 343-353 ◽  
Author(s):  
Alejandro Alarcón ◽  
Mariano García Díaz ◽  
Laura Verónica Hernández Cuevas ◽  
Rosalba Esquivel Cote ◽  
Ronald Ferrera-Cerrato ◽  
...  
Keyword(s):  
Crude Oil ◽  
Plant Species ◽  
Mycorrhizal Fungi ◽  
Root Colonization ◽  
Root Nodules ◽  
Arbuscular Mycorrhizal ◽  
Dry Weight ◽  
Culturable Bacteria ◽  
Brachiaria Brizantha ◽  
Oil Concentration

This research evaluated the changes on populations of culturable N-fixing free bacteria (NFFB) and P-solubilizing bacteria (PSB), as well as on the root nodulation by native rhizobia, the root colonization and spore number of arbuscular mycorrhizal fungi (AMF), in the rhizosphere of Clitoria ternatea and Brachiaria brizantha grown in mesocosms contaminated with crude oil (0, 3000, 6000, 9000, and 12000 mg kg-1), for 240 days. After 24 h of soil contamination, the highest populations of NFFB and PSB (5.5 and 4.9 LogUFC, respectively) were found in control, and the lowest populations were obtained at 12000 mg kg-1 (5.1 and 4.2 LogUFC, respectively). In contrast, at 60 and 240 days, the control showed lower populations of NFFB and PSB (5.4 and 4.8 LogUFC, respectively) than contaminated treatments. The highest number or root nodules in C. ternatea was quantified in control at 60 and 240 days (25 and 27 nodules, respectively) in comparison to those observed at the treatment with 12000 mg kg-1 (7 and 1 nodule, respectively). At 60 days, AMF colonization in both plant species, and the number of spores significantly decreased as the crude oil concentration increased; however, at 240 days, the highest number of AMF spores was recorded at treatments with 6000 and 12000 mg kg-1. The dry weight of both plant species significantly decreased as crude oil concentrations increased. Although C. ternatea was more susceptible to the toxic effects of crude oil, this plant species showed greater content of total chlorophyll than B. brizantha.

scholarly journals Citric acid and AMF Inoculation Combination Assisted phytoextraction of vanadium (V) by Medicago Sativa in V Mining Contaminated Soil

2021 ◽  
Author(s):  
Lang Qiu ◽  
Wenlong Gao ◽  
Zhigang Wang ◽  
Baoqin Li ◽  
Weimin Sun ◽  
...  
Keyword(s):  
Citric Acid ◽  
Medicago Sativa ◽  
Contaminated Soil ◽  
Mycorrhizal Fungi ◽  
Plant Biomass ◽  
Arbuscular Mycorrhizal ◽  
Dry Weight ◽  
Antioxidant Response ◽  
Mycorrhizal Colonization ◽  
Amf Inoculation

Abstract The use of citric acid (CA) chelator to facilitate metal bioavailability is a promising approach for phytoextraction of heavy metal contaminants. However, the role of CA chelator associated with arbuscular mycorrhizal fungi (AMF) inoculation on phytoextraction of vanadium (V) has not been studied. Therefore, in this study, a greenhouse pot experiment was conducted to evaluate the combined effect of CA chelator and AMF inoculation on plant growth and V phytoextraction in the V mining contaminated soil by Medicago sativa Linn. (M. sativa). The experiment was performed via CA (at 0, 5 and 10 mM kg− 1 soil levels) application alone or in combination with AMF inoculation. Plant biomass, root mycorrhizal colonization, P and V accumulation, antioxidant enzyme activity in plant, and soil chemical speciation of V were evaluated. Results depicted (1) a marked decline in plant biomass and root mycorrhizal colonization in 5- and 10-mM CA treatments which were accompanied by a significant increased V accumulation in M. sativa tissues. The effects could be attributed to the enhancement of bioavailable V by mainly transferring from the reducible to acid-soluble V fraction. (2) The presence of CA significantly enhanced P acquisition while the ratio of P/V concentration in plant shoots and roots decreased, owing to the increased V translocation from soil to plant. (3) In both CA treated soil, AMF symbiosis significantly improved dry weight (31.4–73.3%) and P content (37.3-122.5%) in shoot and root of M. sativa, and showed markedly contribution in reduction of malondialdehyde (MDA) content (12.8–16.2%) and higher antioxidants (SOD, POD and CAT) activities in the leaves, suggesting their combination could promote growth performance and stimulate antioxidant response alleviating V stress induced by CA chelator. (4) Taken together, 10 mM kg− 1 CA application and AMF inoculation combination exhibited higher amount of extracted V both in the shoot and root. Thus, citric acid-AMF-plant symbiosis provides a novel remediation strategy for in situ V phytoextraction by M. sativa in the contaminated soil.

Effect of rhizobacteria strains on the induction of resistance in barley genotypes against Cochliobolus sativus

2020 ◽  
Vol 13 (2) ◽  
pp. 83-92 ◽  
Author(s):  
A. Adam
Keyword(s):  
Plant Growth ◽  
Pseudomonas Putida ◽  
Growth Parameters ◽  
Disease Incidence ◽  
Dry Weight ◽  
Cochliobolus Sativus ◽  
Resistance Level ◽  
Wet Weight ◽  
Number Of Leaves ◽  
Barley Genotypes

SummaryEnhancement of the resistance level in plants by rhizobacteria has been proven in several pathosystems. This study investigated the ability of four rhizobacteria strains (Pseudomonas putida BTP1 and Bacillus subtilis Bs2500, Bs2504 and Bs2508) to promote the growth in three barley genotypes and protect them against Cochliobolus sativus. Our results demonstrated that all tested rhizobacteria strains had a protective effect on barley genotypes Arabi Abiad, Banteng and WI2291. However, P. putida BTP1 and B. subtilis Bs2508 strains were the most effective as they reduced disease incidence by 53 and 38% (mean effect), respectively. On the other hand, there were significant differences among the rhizobacteria-treated genotypes on plant growth parameters, such as wet weight, dry weight, plant height and number of leaves. Pseudomonas putida BTP1 strain was the most effective as it significantly increased plant growth by 15-32%. In addition, the susceptible genotypes Arabi Abiad and WI2291 were the most responsive to rhizobacteria. This means that these genotypes have a high potential for increase of their resistance against the pathogen and enhancement of plant growth after the application of rhizobacteria. Consequently, barley seed treatment with the tested rhizobacteria could be considered as an effective biocontrol method against C. sativus.

scholarly journals Mutation in the ntrR Gene, a Member of the vap Gene Family, Increases the Symbiotic Efficiency of Sinorhizobium meliloti

2001 ◽  
Vol 14 (7) ◽  
pp. 887-894 ◽  
Author(s):  
Boglárka Oláh ◽  
Erno Kiss ◽  
Zoltán Györgypál ◽  
Judit Borzi ◽  
Gyöngyi Cinege ◽  
...  
Keyword(s):  
Nitrogen Fixation ◽  
Pathogenic Bacteria ◽  
Sinorhizobium Meliloti ◽  
Root Nodules ◽  
Nifh Gene ◽  
Dry Weight ◽  
Nodule Occupancy ◽  
Gene Encoding ◽  
Symbiotic Efficiency ◽  
Host Interactions

In specific plant organs, namely the root nodules of alfalfa, fixed nitrogen (ammonia) produced by the symbiotic partner Sinorhizobium meliloti supports the growth of the host plant in nitrogen-depleted environment. Here, we report that a derivative of S. meliloti carrying a mutation in the chromosomal ntrR gene induced nodules with enhanced nitrogen fixation capacity, resulting in an increased dry weight and nitrogen content of alfalfa. The efficient nitrogen fixation is a result of the higher expression level of the nifH gene, encoding one of the subunits of the nitrogenase enzyme, and nifA, the transcriptional regulator of the nif operon. The ntrR gene, controlled negatively by its own product and positively by the symbiotic regulator syrM, is expressed in the same zone of nodules as the nif genes. As a result of the nitrogen-tolerant phenotype of the strain, the beneficial effect of the mutation on efficiency is not abolished in the presence of the exogenous nitrogen source. The ntrR mutant is highly competitive in nodule occupancy compared with the wild-type strain. Sequence analysis of the mutant region revealed a new cluster of genes, termed the “ntrPR operon,” which is highly homologous to a group of vap-related genes of various pathogenic bacteria that are presumably implicated in bacterium-host interactions. On the basis of its favorable properties, the strain is a good candidate for future agricultural utilization.

scholarly journals Target of rapamycin, PvTOR, is a key regulator of arbuscule development during mycorrhizal symbiosis in Phaseolus

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Manoj-Kumar Arthikala ◽  
Kalpana Nanjareddy ◽  
Lourdes Blanco ◽  
Xóchitl Alvarado-Affantranger ◽  
Miguel Lara
Keyword(s):  
Arbuscular Mycorrhizal ◽  
Am Fungi ◽  
Target Of Rapamycin ◽  
Mycorrhizal Symbiosis ◽  
Energy Status ◽  
Symbiotic Associations ◽  
Expression Of Genes ◽  
Fungal Symbiosis ◽  
Am Fungus ◽  
Am Symbiosis

AbstractTarget of rapamycin (TOR) is a conserved central growth regulator in eukaryotes that has a key role in maintaining cellular nutrient and energy status. Arbuscular mycorrhizal (AM) fungi are mutualistic symbionts that assist the plant in increasing nutrient absorption from the rhizosphere. However, the role of legume TOR in AM fungal symbiosis development has not been investigated. In this study, we examined the function of legume TOR in the development and formation of AM fungal symbiosis. RNA-interference-mediated knockdown of TOR transcripts in common bean (Phaseolus vulgaris) hairy roots notably suppressed AM fungus-induced lateral root formation by altering the expression of root meristem regulatory genes, i.e., UPB1, RGFs, and sulfur assimilation and S-phase genes. Mycorrhized PvTOR-knockdown roots had significantly more extraradical hyphae and hyphopodia than the control (empty vector) roots. Strong promoter activity of PvTOR was observed at the site of hyphal penetration and colonization. Colonization along the root length was affected in mycorrhized PvTOR-knockdown roots and the arbuscules were stunted. Furthermore, the expression of genes induced by AM symbiosis such as SWEET1, VPY, VAMP713, and STR was repressed under mycorrhized conditions in PvTOR-knockdown roots. Based on these observations, we conclude that PvTOR is a key player in regulating arbuscule development during AM symbiosis in P. vulgaris. These results provide insight into legume TOR as a potential regulatory factor influencing the symbiotic associations of P. vulgaris and other legumes.

scholarly journals Bacterial Leaf Spot of Celery in California: Etiology, Epidemiology, and Role of Contaminated Seed

Plant Disease ◽  
1997 ◽  
Vol 81 (8) ◽  
pp. 892-896 ◽  
Author(s):  
E. L. Little ◽  
S. T. Koike ◽  
R. L. Gilbertson
Keyword(s):  
Pseudomonas Syringae ◽  
Leaf Spot ◽  
Disease Incidence ◽  
Field Tests ◽  
Hot Water ◽  
Disease Development ◽  
Bacterial Leaf Spot ◽  
Overhead Irrigation ◽  
Celery Seed ◽  
Salinas Valley

Pseudomonas syringae pv. apii, causal agent of bacterial leaf spot (BLS) of celery, was first identified in California in 1989. By 1991, BLS was apparent in all celery-growing areas of the state. Greenhouse-produced transplants were affected most severely, and disease incidence approached 100% in some greenhouses. In this study, sources of inoculum and factors contributing to disease development were investigated in three Salinas Valley greenhouse operations during the 1991, 1992, and 1993 celery transplant seasons (January to August). Epiphytic P. syringae pv. apii was not detected on celery transplants until April or May of each year. Increased epiphytic populations preceded BLS outbreaks, and high-pressure, overhead irrigation favored bacterial infiltration and disease development. In seed-wash assays, P. syringae pv. apii was recovered from 5 of 24 commercial celery seed lots. In field tests, epiphytic P. syringae pv. apii was found on umbels of inoculated celery plants, and seeds from these plants were heavily contaminated with P. syringae pv. apii. Contaminated seed produced seedlings with large epiphytic P. syringae pv. apii populations. Hot-water treatment (50°C for 25 min) eliminated >99.9% of seed contamination. Based on these results, disease management techniques are proposed.

scholarly journals Field Evaluations of Leaf Spot Resistance and Yield in Peanut Genotypes in the United States and Bolivia

Plant Disease ◽  
2011 ◽  
Vol 95 (3) ◽  
pp. 263-268 ◽  
Author(s):  
S. K. Gremillion ◽  
A. K. Culbreath ◽  
D. W. Gorbet ◽  
B. G. Mullinix ◽  
R. N. Pittman ◽  
...  
Keyword(s):  
United States ◽  
Disease Resistance ◽  
Leaf Spot ◽  
Field Experiments ◽  
Disease Incidence ◽  
The United States ◽  
Yield Potential ◽  
Cercospora Arachidicola ◽  
Breeding Lines ◽  
Progress Curve

Field experiments were conducted in 2002 to 2006 to characterize yield potential and disease resistance in the Bolivian landrace peanut (Arachis hypogaea) cv. Bayo Grande, and breeding lines developed from crosses of Bayo Grande and U.S. cv. Florida MDR-98. Diseases of interest included early leaf spot, caused by the fungus Cercospora arachidicola, and late leaf spot, caused by the fungus Cercosporidium personatum. Bayo Grande, MDR-98, and three breeding lines, along with U.S. cvs. C-99R and Georgia Green, were included in split-plot field experiments in six locations across the United States and Bolivia. Whole-plot treatments consisted of two tebuconazole applications and a nontreated control. Genotypes were the subplot treatments. Area under the disease progress curve (AUDPC) for percent defoliation due to leaf spot was lower for Bayo Grande and all breeding lines than for Georgia Green at all U.S. locations across years. AUDPC for disease incidence from one U.S. location indicated similar results. Severity of leaf spot epidemics and relative effects of the genotypes were less consistent in the Bolivian experiments. In Bolivia, there were no indications of greater levels of disease resistance in any of the breeding lines than in Bayo Grande. In the United States, yields of Bayo Grande and the breeding lines were greater than those of the other genotypes in 1 of 2 years. In Bolivia, low disease intensity resulted in the highest yields in Georgia Green, while high disease intensity resulted in comparable yields among the breeding lines, MDR-98, and C-99R. Leaf spot suppression by tebuconazole was greater in Bolivia than in the United States. This result indicates a possible higher level of fungicide resistance in the U.S. population of leaf spot pathogens. Overall, data from this study suggest that Bayo Grande and the breeding lines may be desirable germplasm for U.S. and Bolivian breeding programs or production.

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