scholarly journals Local and Systemic Effects of NaCl on Root Composition, Rhizobacteria, and Fusarium Crown and Root Rot of Asparagus

2003 ◽  
Vol 93 (2) ◽  
pp. 186-192 ◽  
Author(s):  
Wade H. Elmer
Keyword(s):  
Root System ◽  
Root Rot ◽  
Root Exudation ◽  
Root Culture ◽  
Chloride Ions ◽  
Disease Suppression ◽  
Na Ions ◽  
Crown And Root Rot ◽  
Root Tissues ◽  
Reducing Bacteria

The role of NaCl in suppression of Fusarium crown and root rot of asparagus was investigated in split root culture so the direct effects of NaCl on the root and rhizosphere could be separated from effects that were translocated to the nontreated root side. One side of the root system was exposed to 100 ml of 0, 0.5, or 1.0% NaCl, while the other side received deionized water. Both sides of the root system were inoculated with conidial suspensions of the pathogens Fusarium oxysporum and F. proliferatum. When plants were harvested and assayed, root lesions and CFUs of F. oxysporum or F. proliferatum per centimeter of root from both exposed and nonexposed roots decreased as the NaCl rate increased to 1.0%, but the reduction relative to the control was significantly greater on roots that were directly exposed to NaCl (51% reduction in root lesions) than on adjacent nonexposed roots (31% reduction in root lesions). On both sides of the root systems, disease suppression with NaCl was associated with increases in the rhizosphere densities of fluorescent pseudomonads and Mn-reducing bacteria in the rhizosphere soil. In addition, as the NaCl rate increased, root tissues had marked reductions in malic acid and amino acids while concentrations of Cl and Mn increased in equal proportions on both sides of the root system. Chloride ions were absorbed in greater amounts than Na ions, and were more mobile in the plant than Na. Plants treated with 1% NaCl (171 meq of Cl- per liter) had soil leachates 1 week later of 47 meq of Cl- per liter from pots exposed to NaCl, but in the adjacent nonexposed pots, the amount of Cl in the leachates slowly increased over the course of the study to 20 meq/liter, presumably through the root exudation. These findings suggest that suppression of Fusarium crown and root rot of asparagus with NaCl may be due to multiple mechanisms. Maximum suppression occurs when NaCl is directly applied to roots, but suppression still occurs on distal non-treated roots resulting from systemic mechanisms. The latter mechanism may be associated with a root-mediated alteration in the rhizobacteria.

scholarly journals First Report of a Phytopythium litorale Species Causing Crown and Root Rot on Rhododendron pulchrum in China

Plant Disease ◽  
2021 ◽  
Author(s):  
Yaxing Li ◽  
Yangfan Feng ◽  
Cuiping Wu ◽  
Junxin Xue ◽  
Binbin Jiao ◽  
...  
Keyword(s):  
Root Rot ◽  
Morphological Characters ◽  
Morphological Features ◽  
Crown Rot ◽  
Sterile Water ◽  
First Report ◽  
Inoculation Method ◽  
Platanus Orientalis ◽  
Crown And Root Rot ◽  
Root Tissues

During a survey of pathogenic oomycetes in Nanjing, China from June 2019 to October 2020, at least ten adjacent Rhododendron pulchrum plants at a Jiangjun Mountain scenic spot showed symptoms of blight, and crown and root discoloration . Symptomatic root tissues collected from three 6-year-old plants were rinsed with water, cut into 10-mm pieces, surface sterilized with 70% ethanol for 1 min, and plated onto 10% clarified V8 PARP agar (cV8A-PARP) containing pimaricin (20 mg/liter), ampicillin (125 mg/liter), rifampicin (10 mg/liter), and pentachloronitrobenzene (20 mg/liter). Four Pythium-like isolates were recovered after three days of incubation at 26°C, and purified using hyphal-tipping. Ten agar plugs (2×2 mm2) of each isolate were grown in 10 mL of 10% clarified V8 juice (cV8) in a 10 cm plate at 26°C for 3 days to produce mycelial mats, and then the cV8 was replaced with sterile water. To stimulate sporangial production, three to five drops of soil extract solution were added to each plate. Sporangia were terminal, ovoid to globose, and the size is 24 to 45.6 (mean 34.7) (n=10.8) in length x 23.6 to 36.0 (mean 29.8) (n=6.2) in width. Gametangia were not observed in cV8A or liquid media after 30 days. For colony morphology, the isolates were sub-cultured onto three solid microbial media (cV8A-PARP, potato dextrose agar, corn meal agar) . All isolates had identical morphological features in the three media. Complete ITS and partial LSU and cox2 gene regions were amplified using primer pairs ITS1/ITS4, NL1/NL4, and FM58/FM66 , respectively. The ITS, LSU, and cox2 sequences of isolate PC-dj1 (GenBank Acc. No. MW205746, MW208002, MW208003) were 100.00% (936/936 nt), 100.00% (772/772 nt), and 99.64% (554/556 nt) identical to those of JX985743, MT042003, and GU133521, respectively. We built a maximum-likelihood tree of Phytopythium species using the concatenated dataset (ITS, LSU, cox2) to observe interspecific differences. Based on the morphological characters and sequences, isolate PC-djl was identified as Phytopythium litorale . As the four isolates (PC-dj1, PC-dj2, PC-dj3 and PC-dj4) tested had identical morphological characters and molecular marker sequences, the pathogenicity of the representative isolate, PC-dj1, was tested using two inoculation methods on ten one-year-old R. pulchrum plants. For the first inoculation method, plants were removed from the pot, and their roots were rinsed with tap water to remove the soil. Each of these plants was placed in a glass flask containing 250 mL of sterile water and 10 blocks (10 x 10 mm2) of mycelial mats harvested from a three-day-old culture of P. litorale, while the other plant was placed in sterile water as a control, and incubated at 26°C. After three days, symptoms including crown rot, root rot and blight was observed on the inoculated plants whereas the control remained asymptomatic. For the second inoculation method, ten plants were dug up to expose the root ball. Ten three-day-old cV8A plugs (5×5 mm2) from a PC-dj1 culture or sterile cV8A plugs were evenly insert into the root ball of a plant before it was planted back into the original pots. Both plants were maintained in a growth chamber set at 26°C with a 12/12 h light/dark cycle and irrigated as needed. After 14 to 21 days, the inoculated plant had symptoms resembling those in the field , while the control plant remained asymptomatic. Each inoculation method was repeated at triplicate and the outcomes were identical. Phytopythium isolates with morphological features and sequences identical to those of PC-dj1 were recovered from rotted crown and root tissues of all inoculated plants. Previously, P. litorale was found causing diseases of apple and Platanus orientalis in Turkey, fruit rot and seedling damping-off of yellow squash in southern Georgia, USA. This is the first report of this species causing crown and root rot on R. pulchrum, an important ornamental plant species in China. Additional surveys are ongoing to determine the distribution of P. litorale in the city of Nanjing.

scholarly journals Cytological Aspects of Compost-Mediated Induced Resistance Against Fusarium Crown and Root Rot in Tomato

2002 ◽  
Vol 92 (4) ◽  
pp. 424-438 ◽  
Author(s):  
Benoît Pharand ◽  
Odile Carisse ◽  
Nicole Benhamou
Keyword(s):  
Induced Resistance ◽  
Root Rot ◽  
Disease Incidence ◽  
Disease Suppression ◽  
Gold Complex ◽  
Peat Moss ◽  
Fungal Colonization ◽  
Pythium Oligandrum ◽  
Vascular Elements ◽  
Crown And Root Rot

The potential of a pulp and paper mill residues compost for the control of crown and root rot of greenhouse-grown tomato caused by Fusarium oxysporum f. sp. radicis-lycopersici was ultrastructurally investigated. Peat moss amended with compost substantially reduced disease-associated symptoms. Addition of Pythium oligandrum to either peat moss alone or peat moss amended with compost resulted in a considerable reduction in disease incidence compared with controls grown in peat moss alone. Histological and cytological observations of root samples from Fusarium-inoculated plants revealed that the beneficial effect of compost in reducing disease symptoms is associated with increased plant resistance to fungal colonization. One of the most prominent facets of compost-mediated induced resistance concerned the formation of physical barriers at sites of attempted fungal penetration. These structures, likely laid down to prevent pathogen ingress toward the vascular elements, included callose-enriched wall appositions and osmiophilic deposits around the sites of potential pathogen ingress. Invading hyphae, coated by the osmiophilic material, showed marked cellular disorganization. The use of the wheat germ agglutinin-ovomucoid-gold complex provided evidence that the wall-bound chitin was altered in severely damaged hyphae. A substantial increase in the extent and magnitude of the cellular changes induced by compost was observed when P. oligandrum was supplied to the potting substrate. This finding corroborates the current concept that amendment of composts with specific antagonists may be a valuable option for amplifying their beneficial properties in terms of plant disease suppression.

scholarly journals First Report of Phytopythium helicoides Causing Crown and Root Rot on Rhododendron pulchrum in China

Plant Disease ◽  
2020 ◽  
Author(s):  
Zhenpeng Chen ◽  
Xiao Yang ◽  
Junxin Xue ◽  
Binbin Jiao ◽  
Yaxing Li ◽  
...  
Keyword(s):  
Cytochrome C ◽  
Cytochrome C Oxidase ◽  
Root Rot ◽  
Internal Transcribed Spacer ◽  
Its Region ◽  
Morphological Features ◽  
Mitochondrial Cytochrome ◽  
Foliage Blight ◽  
Crown And Root Rot ◽  
Root Tissues

During a 2019–2020 survey of plant pathogenic oomycetes in Nanjing, China, a cluster of five adjacent Rhododendron pulchrum plants in Xuanwuhu Park exhibited symptoms including crown and root rot and wilting. foliage blight caused due to collar and had rotting crown and root tissues resultingrot foliage blight. Diseased roots were rinsed in water, cut into 10 mm pieces, immersed in 70% ethanol for 60 sec, and plated onto clarified V8 juice agar (cV8A) containingamended with pimaricin (20 mg/liter), ampicillin (125 mg/liter), rifampicin (10 mg/liter), and pentachloronitrobenzene (20 mg/liter). After three3 days of incubation at 26°C, Ffive Pythium-like isolatescoloniesisolates were obtained using hypalhyphal-tipping after 3 days of incubation at 25°C. Ten agar plugs (2×2 mm2) of each isolate were growntransferred into 10 mLl of 10% clarified V8 juice (cV8) in a 100 -mm plate at 26°C to produce mycelial mats. After 3three days, cV8 was replaced with sterile water. To stimulate sporangial production, 3–5 drops of soil extract solution were added to each plate. Five isolates had identical morphological features. Sporangia were terminal, ovoid to globose, andmeasuring 34.2 ± 6.2 µm (24.0–42.5 µm range) in length and 30.7 ± 6.6 µm (20.9–41.1 µm range) in width. Oogonia were not observed. The following primers were used to amplify the rDNA internal transcribed spacer (ITS) region and the mitochondrial cytochrome c oxidase subunit 1 (cox1COI) and 2 (cox2COII) genes  of from aA representative isolate, PH-C were amplified using the primer pairs ITS6 and ITS4 (Cooke et al. 2000), OomCoxI-Levup and OomCoxI-Levlo (Robideau et al. 2011) and Cox2-F and Cox2-RC4 (Hudspeth et al. 2000), respectivelyPhe-1. Isolate A xxx675 bp, xxx657 bp and 561xxx bp fragmentPH-C , respectively were amplified and had have identical sequences of the ITS (GenBank ACN. MT824568), and cox1 (MT834959), COI and cox2 COII genes the rDNA internal transcribed spacer (ITS) region and the mitochondrial cytochrome c oxidase subunit 1 and 2 genes (GenBank ACN. MT824568, MT834959, (MT834958, respectively) sequences identical to those of Phytopythium helicoides (MN541109, MK879709, KT595689, respectively). Based on the morphological and molecular characters, all five isolatesthe causal agent waswere identified the species represented by Phe-1 was identified as P. helicoides. One-year-old R. pulchrum plants (approx. 0.3 m in height) grown in 8×8 cm2 pots were used in to test the pathogenicity trials. Ten plants wasere carefully dug up to expose root ballsclusterballs. TenThree- days -old cultures of the isolate PH-Che-1 were used as the inoculum. Five The pplantss wereere inoculated by inserting 10 agar plugs into thee root ball of each plantcluster. For inoculatingfive control plants, sterile cV8A discsplugs were used. All inoculated plants were re-potted using original fresh potting mix and potsture .Ten 3-day-old cV8A cultural plugs (5×5 mm2) of Phe-1 were evenly insert into the root ball of each of five plants, while sterile cV8A plugs were used for five control plants. All were then planted into their original pots. Plants were maintained in a growth chamber set at 26°C with a 12/12 h light/dark cycle and irrigated as needed. After 21–25 days, the inoculated plants had symptoms identical to those in the field, while the controls remained asymptomatic. Identical outcomes were obtained from two repeated The pathogenicity trials. test was repeatedconducted twice . and the coutcome was identical. Phytopythium. helicoides (Phe-1) was reisolated from all symptomatic plants inemerging from the pathogenicity trials. Phytopythium helicoides was found causing diseases of Asian lotus (Yin et al. 2015), mandarin orange (Chen et al. 2016), and kiwifruit (Wang et al. 2015) plants in China. Phytopythium isolates with identical morphological features to those of Phe-1 were recovered from rotted crown and root tissues of all inoculated plants. In this note, P. helicoides causing crown and root rot on R. pulchrum is reported for the first time. Globally, this is the first report of P. helicoides causing crown blight and root rot of R. pulchrum. Additional surveys are being conducted forto mapping the distribution of P. helicoides in Nanjing, Province of China.

scholarly journals Soil Suppressiveness to Fusarium Disease Following Organic Amendments and Solarization

Plant Disease ◽  
2011 ◽  
Vol 95 (9) ◽  
pp. 1116-1123 ◽  
Author(s):  
Eyal Klein ◽  
Jaacov Katan ◽  
Abraham Gamliel
Keyword(s):  
Root Rot ◽  
Disease Incidence ◽  
Chemical Properties ◽  
Additional Treatment ◽  
Disease Suppression ◽  
Mentha Piperita ◽  
Plant Residues ◽  
Soilborne Pathogens ◽  
Soil Suppressiveness ◽  
Crown And Root Rot

Soil suppressiveness to soilborne pathogens can evolve following the incorporation of plant residues in the soil and solarization. We studied its occurrence by assessing disease incidence and severity in sandy soil which was infested after the disinfestation treatment. Disease incidence and severity of crown and root rot in cucumber plants inoculated with Fusarium oxysporum f. sp. radicis-cucumerinum macroconidia were reduced by 20 to 80% when seedlings were planted in the tested soils 2 to 34 months after soil amendment. Residues of Diplotaxis tenuifolia (wild rocket [WR]), Artemisia dracunculus (tarragon), Salvia officinalis (sage), and Brassica oleracea var. italica (broccoli) were most effective for inducing soil suppressiveness. Effective soil suppressiveness continued to be evident after repeated inoculations and plantings in the same soil without additional treatment between inoculations. Moreover, residues of WR induced soil suppressiveness in two additional tested soils differing in their physical and chemical properties. Residues of Rosmarinus officinalis (rosemary), Coriandrum sativum (coriander), Mentha piperita (peppermint), and B. oleraceae var. botrytis (cauliflower) induced disease suppression at the first inoculated planting but not upon repeated inoculation and planting. The contribution of soil solarization to the evolution of soil suppressiveness, albeit evident, was inconsistent. Soil suppressiveness to Fusarium crown and root rot was also observed when cucumber seed were sown in soils which were initially amended with WR residues and later infested with F. oxysporum f. sp. radicis-cucumerinum chlamydospores. There is a potential for the use of plant residues for inducing soil suppressiveness and further contributing to the control of diseases caused by soilborne pathogens.

scholarly journals Factors Associated with Fusarium Crown and Root Rot of Asparagus Outbreaks in Quebec

2005 ◽  
Vol 95 (8) ◽  
pp. 867-873 ◽  
Author(s):  
Chantal Hamel ◽  
Vladimir Vujanovic ◽  
Aiko Nakano-Hylander ◽  
Richard Jeannotte ◽  
Marc St-Arnaud
Keyword(s):  
Root Rot ◽  
Management Practices ◽  
Negative Impact ◽  
Fusarium Spp ◽  
Data Set ◽  
Exploratory Approach ◽  
Plantation Age ◽  
Crown And Root Rot ◽  
Reducing Bacteria ◽  
Field Area

The Fusarium spp. causing Fusarium crown and root rot (FCRR) are ubiquitous and abundant in soils, but in contrast, disease expression is localized and sporadic. Previous studies have related FCRR infection to phenolic acids released by asparagus, to the repression of Mn-reducers in soil, and to various soil physicochemical conditions. Fifty commercial asparagus plantations were surveyed using an exploratory approach in order to pinpoint the ecological conditions associated with FCRR development. Twenty-eight variables were used to describe the soil environments of the asparagus crops as well as the influence of crop management practices used locally. The data set was analyzed both as a whole and parsed by main cultivars (Jersey Giant and Guelph Millenium). Both field conditions and percentage of field area affected by FCRR varied widely between asparagus plantations. Planting depth was positively correlated with percentage of field area affected by FCRR and, hence, deep planting may favor FCRR infection. Plantation age was positively correlated with percentage of field area affected by FCRR, while soil available Mn was inversely correlated. Most importantly, soil Mn availability decreased with increasing plantation age, supporting the hypothesis of an asparagusmediated negative impact on Mn-reducing bacteria and of the involvement of reduced Mn availability in FCRR development. Improving the availability of Mn could provide a solution to the problem of FCRR in asparagus plantations.

scholarly journals Cellulase Activity as a Mechanism for Suppression of Phytophthora Root Rot in Mulches

2011 ◽  
Vol 101 (2) ◽  
pp. 223-230 ◽  
Author(s):  
Brantlee Spakes Richter ◽  
Kelly Ivors ◽  
Wei Shi ◽  
D. M. Benson
Keyword(s):  
Root Rot ◽  
Phytophthora Cinnamomi ◽  
Cellulase Activity ◽  
Enzyme Concentration ◽  
Disease Suppression ◽  
In Vitro Assays ◽  
Infested Soil ◽  
Phytophthora Root Rot ◽  
Standard Curve

Wood-based mulches are used in avocado production and are being tested on Fraser fir for reduction of Phytophthora root rot, caused by Phytophthora cinnamomi. Research with avocado has suggested a role of microbial cellulase enzymes in pathogen suppression through effects on the cellulosic cell walls of Phytophthora. This work was conducted to determine whether cellulase activity could account for disease suppression in mulch systems. A standard curve was developed to correlate cellulase activity in mulches with concentrations of a cellulase product. Based on this curve, cellulase activity in mulch samples was equivalent to a cellulase enzyme concentration of 25 U ml–1 or greater of product. Sustained exposure of P. cinnamomi to cellulase at 10 to 50 U ml–1 significantly reduced sporangia production, but biomass was only reduced with concentrations over 100 U ml–1. In a lupine bioassay, cellulase was applied to infested soil at 100 or 1,000 U ml–1 with three timings. Cellulase activity diminished by 47% between 1 and 15 days after application. Cellulase applied at 100 U ml–1 2 weeks before planting yielded activity of 20.08 μmol glucose equivalents per gram of soil water (GE g–1 aq) at planting, a level equivalent to mulch samples. Cellulase activity at planting ranged from 3.35 to 48.67 μmol GE g–1 aq, but no treatment significantly affected disease progress. Based on in vitro assays, cellulase activity in mulch was sufficient to impair sporangia production of P. cinnamomi, but not always sufficient to impact vegetative biomass.

White root rot disease suppression in rubber plant with microbial co-inoculants and silicon addition

Rhizosphere ◽  
2020 ◽  
Vol 15 ◽  
pp. 100221
Author(s):  
Imran Shabbir ◽  
Mohd Yusoff Abd Samad ◽  
Radziah Othman ◽  
Mui-Yun Wong ◽  
Zulkefly Sulaiman ◽  
...  
Keyword(s):  
Root Rot ◽  
Disease Suppression ◽  
White Root Rot ◽  
Root Rot Disease ◽  
Rubber Plant ◽  
Silicon Addition ◽  
Rot Disease

EVALUATION OF ALFALFA CULTIVARS FOR REACTION TO CROWN AND ROOT ROT

1985 ◽  
Vol 65 (1) ◽  
pp. 95-98 ◽  
Author(s):  
R. MICHAUD ◽  
C. RICHARD
Keyword(s):  
Disease Severity ◽  
Root Rot ◽  
Dry Matter ◽  
Forage Yield ◽  
Dry Matter Yield ◽  
Crown And Root Rot ◽  
Disease Free

Fourteen alfalfa cultivars were grown for 2 yr at three locations and evaluated for forage dry matter yield and crown and root rot. Significant differences were found among cultivars for dry matter yield. All cultivars were affected by crown and root rot, most cultivars showing between 20 and 30% of infected tissues. Differences were observed among as well as within the cultivars for disease severity. The frequency of disease-free plants was less than 1.3% of the plants evaluated. Correlation between root rot index and forage yield was −0.87 [Formula: see text] when data were pooled over years and locations.Key words: Lucerne, root rot, cultivar, yield

scholarly journals Gene Expression Profiling of a Compatible Interaction Between Douglas-Fir and the Root Rot Fungal Pathogen Phellinus sulphurascens

2013 ◽  
Vol 103 (6) ◽  
pp. 583-593 ◽  
Author(s):  
M. A. Islam ◽  
Rona N. Sturrock ◽  
Abul K. M. Ekramoddoullah
Keyword(s):  
Cdna Library ◽  
Root Rot ◽  
Douglas Fir ◽  
Coniferous Species ◽  
Elevated Expression ◽  
Plant Genes ◽  
Polymerase Chain ◽  
Fungal Genes ◽  
Root Tissues ◽  
Host Genes

Douglas-fir (DF) (Pseudotsuga menziesii) is one of the largest and most economically important coniferous species in western North America. Its productivity is greatly affected by the root rot fungus Phellinus sulphurascens Pilát. Evidence of resistance by DF to fungal root pathogens such as P. sulphurascens has been reported but mechanisms of resistance in this compatible pathosystem are not yet known. To better understand the DF–P. sulphurascens interaction, especially at the molecular level, we selected 12 diverse plant genes already identified as defense-related from a cDNA library constructed using root tissues from P. sulphurascens-infected DF seedlings. Using quantitative reverse-transcriptase polymerase chain reaction on infected DF root samples collected at five different time points after inoculation, we found that P. sulphurascens infection significantly elevated expression of the 12 selected genes. In most cases the highest expression level was recorded within 2 to 3 days after inoculation. The constructed cDNA library, which is enriched with defense-related host genes and a number of fungal genes, will continue to serve as a useful resource for future larger-scale gene discovery and functional research on the P. sulphurascens and DF pathosystem.

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