scholarly journals Induction of Systemic Acquired Resistance Aids Restoration of Tree Health in Field-Grown Pear and Apple Diseased with Fire Blight

Plant Disease ◽  
2017 ◽  
Vol 101 (7) ◽  
pp. 1263-1268 ◽  
Author(s):  
Kenneth B. Johnson ◽  
Todd N. Temple
Keyword(s):  
Active Ingredient ◽  
Fire Blight ◽  
Tree Mortality ◽  
Systemic Acquired Resistance ◽  
Field Experiments ◽  
Acquired Resistance ◽  
Apple Trees ◽  
Tree Health ◽  
Disease Symptoms ◽  
Made In

Induction of systemic acquired resistance as a therapeutic aid to restoration of tree health was evaluated in 3- to 14-year-old pear and apple trees diseased with fire blight. Acibenzolar-S-methyl (ASM) was applied to diseased trees in late spring near the time of removal of primary fire blight cankers, which had originated from floral infection. Suspensions of ASM (7.5 to 22.5 g of active ingredient per liter plus silicone surfactant) were painted onto a 30- to 45-cm length of branch tissue immediately below primary pruning cuts or sprayed onto an 80- to 100-cm length of central trunk. In some experiments, a second ASM treatment was made in late June to early July in conjunction with secondary pruning of redeveloped cankers. After pruning primary cankers, effects of ASM were measured by assessing weight and length of secondary cankers that were the result of fire blight redevelopment. Over 5 years of field experiments, trees that received an ASM treatments yielded 62% less diseased wood at the time of secondary and tertiary canker removal compared with non-ASM-treated trees. Moreover, tree mortality and proportion of pruning cuts where fire blight redeveloped were reduced by ASM. Induction of systemic acquired resistance could prove practical as an aid to pruning therapy in young, fire-blight-susceptible pear and apple trees where, after canker removal, disease symptoms frequently redevelop owing to residual cells of the pathogen distributed within symptomless portions of the tree.

scholarly journals Effect of Treating Apple Trees with Acibenzolar-S-Methyl on Fire Blight and Expression of Pathogenesis-Related Protein Genes

Plant Disease ◽  
2002 ◽  
Vol 86 (7) ◽  
pp. 785-790 ◽  
Author(s):  
Kimberly Maxson-Stein ◽  
Sheng-Yang He ◽  
Raymond Hammerschmidt ◽  
Alan L. Jones
Keyword(s):  
Fire Blight ◽  
Systemic Acquired Resistance ◽  
Natural Infection ◽  
Acquired Resistance ◽  
Weekly Schedule ◽  
Apple Trees ◽  
Pathogenesis Related Protein ◽  
Pathogenesis Related ◽  
Fuji Apple ◽  
In Fire

Acibenzolar-S-methyl (ASM, Actigard 50 WG), a synthetic inducer of systemic acquired resistance (SAR) and pathogenesis-related (PR) proteins, was evaluated for the control of fire blight on apple trees in the field and for PR protein gene expression in apple seedlings in the greenhouse. Expression of putative genes related to SAR induction was elevated in ASM-treated apple seedlings 2 to 7 days after treatment; levels of PR-1 and PR-8 RNA were increased 10-fold and PR-2 RNA was increased 100-fold in ASM-treated seedlings over levels in untreated seedlings. Spurs and shoots on Jonathan trees sprayed with ASM at 75 mg a.i./liter at pink and at weekly intervals thereafter had significantly less fire blight than untreated trees, both from natural infection and following artificial inoculation with the pathogen. Less fire blight was observed on trees sprayed weekly with ASM than on trees sprayed biweekly. The severity of fire blight on inoculated shoots of Fuji apple decreased with increasing rates of ASM (0 to 300 mg a.i./liter), and ASM combined with streptomycin showed enhanced activity over ASM at 75 mg a.i./liter alone. In general, ASM was not superior to streptomycin for fire blight control, but integrating a weekly schedule of ASM, preferably at 150 mg a.i./liter, with a schedule of streptomycin designed for blossom blight control appears promising for overall improvement in fire blight control.

scholarly journals Field Control of Bacterial Spot and Bacterial Speck of Tomato Using a Plant Activator

Plant Disease ◽  
2001 ◽  
Vol 85 (5) ◽  
pp. 481-488 ◽  
Author(s):  
F. J. Louws ◽  
M. Wilson ◽  
H. L. Campbell ◽  
D. A. Cuppels ◽  
J. B. Jones ◽  
...  
Keyword(s):  
Pseudomonas Syringae ◽  
Systemic Acquired Resistance ◽  
Field Experiments ◽  
Production Systems ◽  
Acquired Resistance ◽  
Dry Weight ◽  
Bacterial Spot ◽  
Population Densities ◽  
Bacterial Speck ◽  
Plant Activator

Acibenzolar-S-methyl (CGA 245704 or Actigard 50WG) is a plant activator that induces systemic acquired resistance (SAR) in many different crops to a number of pathogens. Acibenzolar-S-methyl was evaluated for management of bacterial spot (Xanthomonas axonopodis pv. vesicatoria) and bacterial speck (Pseudomonas syringae pv. tomato) of tomato in 15 and 7 field experiments, respectively. Experiments were conducted over a 4-year period in Florida, Alabama, North Carolina, Ohio, and Ontario using local production systems. Applied at 35 g a.i. ha-1, acibenzolar-S-methyl reduced foliar disease severity in 14 of the 15 bacterial spot and all 7 bacterial speck experiments. Disease control was similar or superior to that obtained using a standard copper bactericide program. Acibenzolar-S-methyl also reduced bacterial fruit spot and speck incidence. Tomato yield was not affected by using the plant activator in the field when complemented with fungicides to manage foliar fungal diseases, but tomato transplant dry weight was negatively impacted. X. axonopodis pv. vesicatoria population densities on greenhouse-grown tomato transplants were reduced by acibenzolar-S-methyl treatment. Bacterial speck and spot population densities on leaves of field-grown plants were not dramatically affected. Acibenzolar-S-methyl can be integrated as a viable alternative to copper-based bactericides for field management of bacterial spot and speck, particularly where copper-resistant populations predominate.

scholarly journals Comparison of Methods of Acibenzolar-S-Methyl Application for Post-Infection Fire Blight Suppression in Pear and Apple

Plant Disease ◽  
2016 ◽  
Vol 100 (6) ◽  
pp. 1125-1131 ◽  
Author(s):  
Kenneth B. Johnson ◽  
Todd N. Temple
Keyword(s):  
Fire Blight ◽  
Systemic Acquired Resistance ◽  
Acquired Resistance ◽  
Foliar Spray ◽  
Field Research ◽  
Apple Rootstocks ◽  
Pr Genes ◽  
Treatment Timing ◽  
Guide Field ◽  
Pathogenesis Related

Greenhouse-grown, 1-year-old potted ‘Bosc’ pear and apple rootstock cultivars ‘M.9’ and ‘M.26’ were inoculated with the fire blight pathogen, Erwinia amylovora, and subjected to trunk paint, root drench, or foliar spray treatments with acibenzolar-S-methyl (ASM, 4 to 30 mg a.i./tree) to induce systemic acquired resistance. Each method of ASM treatment suppressed fire blight canker expansion by 22 to 25%. Furthermore, ASM application method and ASM treatment timing (at or ±3 weeks relative to inoculation) interacted significantly (P ≤ 0.02) in each experiment. A root drench was most effective when applied 3 weeks before inoculation (36% suppression) whereas trunk paints and foliar sprays were more effective at inoculation (43 and 34%, suppression, respectively). Sizes of fire blight cankers in potted apple rootstocks M.9 and M.26 (under scions ‘Gala’ or ‘Cameo’) inoculated directly with the pathogen were reduced by 82 and 87% after two pretreatments of ASM applied as a trunk paint or root drench, respectively. Expression of pathogenesis-related (PR) genes PR-1 and -2 in apple leaves sampled after an ASM trunk paint were elevated significantly (P ≤ 0.05) relative to control trees for at least 9 weeks after treatment. Results of this study are being used to guide field research on postinfection therapy with ASM in 1- to 10-year-old pear and apple trees where fire blight has proven difficult to manage with therapeutic pruning only.

Salicylic Acid: Biosynthesis and Signaling

2021 ◽  
Vol 72 (1) ◽  
Author(s):  
Yujun Peng ◽  
Jianfei Yang ◽  
Xin Li ◽  
Yuelin Zhang
Keyword(s):  
Salicylic Acid ◽  
Systemic Acquired Resistance ◽  
Current Knowledge ◽  
Plant Immunity ◽  
Acquired Resistance ◽  
Annual Review ◽  
Publication Date ◽  
Basal Defense ◽  
Made In ◽  
Key Questions

Salicylic acid (SA) is an essential plant defense hormone that promotes immunity against biotrophic and semibiotrophic pathogens. It plays crucial roles in basal defense and the amplification of local immune responses, as well as the establishment of systemic acquired resistance. During the past three decades, immense progress has been made in understanding the biosynthesis, homeostasis, perception, and functions of SA. This review summarizes the current knowledge regarding SA in plant immunity and other biological processes. We highlight recent breakthroughs that substantially advanced our understanding of how SA is biosynthesized from isochorismate, how it is perceived, and how SA receptors regulate different aspects of plant immunity. Some key questions in SA biosynthesis and signaling, such as how SA is produced via another intermediate benzoic acid and how SA affects the activities of its receptors in the transcriptional regulation of defense genes, remain to be addressed. Expected final online publication date for the Annual Review of Plant Biology, Volume 72 is May 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

scholarly journals A Single Effector Protein, AvrRpt2EA, from Erwinia amylovora Can Cause Fire Blight Disease Symptoms and Induces a Salicylic Acid–Dependent Defense Response

2018 ◽  
Vol 31 (11) ◽  
pp. 1179-1191 ◽  
Author(s):  
Susan Schröpfer ◽  
Christoph Böttcher ◽  
Thomas Wöhner ◽  
Klaus Richter ◽  
John Norelli ◽  
...  
Keyword(s):  
Salicylic Acid ◽  
Fire Blight ◽  
Systemic Acquired Resistance ◽  
Erwinia Amylovora ◽  
Acquired Resistance ◽  
Inducible Promoter ◽  
Marker Genes ◽  
Effector Protein ◽  
In Planta ◽  
Natural Fire

The AvrRpt2EA effector protein of Erwinia amylovora is important for pathogen recognition in the fire blight–resistant crabapple Malus × robusta 5; however, little is known about its role in susceptible apples. To study its function in planta, we expressed a plant-optimized version of AvrRpt2EA driven by a heat shock–inducible promoter in transgenic plants of the fire blight–susceptible cultivar Pinova. After induced expression of AvrRpt2EA, transgenic lines showed shoot necrosis and browning of older leaves, with symptoms similar to natural fire blight infections. Transgenic expression of this effector protein resulted in an increase in the expression of the salicylic acid (SA)-responsive PR-1 gene but, also, in the levels of SA and its derivatives, with diverse kinetics in leaves of different ages. In contrast, no increase of expression levels of VSP2 paralogs, used as marker genes for the activation of the jasmonic acid (JA)-dependent defense pathway, could be detected, which is in agreement with metabolic profiling of JA and its derivatives. Our work demonstrates that AvrRpt2EA acts as a virulence factor and induces the formation of SA and SA-dependent systemic acquired resistance.

scholarly journals Effect of Benzothiadiazole on Transmission of X-Disease Phytoplasma by the Vector Colladonus montanus to Arabidopsis thaliana, a New Experimental Host Plant

Plant Disease ◽  
2005 ◽  
Vol 89 (10) ◽  
pp. 1121-1124 ◽  
Author(s):  
Alberto Bressan ◽  
Alexander H. Purcell
Keyword(s):  
Arabidopsis Thaliana ◽  
Systemic Acquired Resistance ◽  
Detrimental Effect ◽  
Acquired Resistance ◽  
Foliar Spray ◽  
Wild Type ◽  
Chain Reaction ◽  
Disease Symptoms ◽  
Phytoplasma Infection ◽  
Polymerase Chain

Colladonus montanus (Van Duzee), a leafhopper vector of X-disease phytoplasma (Xp), efficiently transmitted the pathogen to Arabidopsis thaliana Columbia wild type. During transmission trials, the phytoplasma was inoculated into 22-, 34-, and 40-day-old plants. Phytoplasma infections were confirmed by polymerase chain reaction (PCR) using primers specific for Xp Symptoms in Xp-positive A. thaliana were overall stunting and reduced or no fruit (silques). All symptom-free plants were PCR negative. Leafhopper nymphs free of Xp that fed on diseased A. thaliana acquired and transmitted Xp to celery plants, a diagnostic host, causing typical X-disease symptoms. Foliar spray applications of the plant resistance elicitor benzothiadiazole (BTH) to A. thaliana 1 week before phytoplasma inoculation significantly reduced phytoplasma infection, ranging from an infection rate of 73.7% for untreated plants to 50 and 35% for plants treated with 1.2 and 4.8 mM BTH, respectively. Vector leafhoppers survival was significantly reduced on BTH-treated A. thaliana compared with leafhoppers on nontreated plants, suggesting that systemic acquired resistance in this plant may have some detrimental effect on the leafhopper C. montanus.

scholarly journals Systemic Acquired Resistance Delays Race Shifts to Major Resistance Genes in Bell Pepper

2004 ◽  
Vol 94 (12) ◽  
pp. 1376-1382 ◽  
Author(s):  
A. M. Romero ◽  
D. F. Ritchie
Keyword(s):  
Disease Severity ◽  
Plant Disease Resistance ◽  
Plant Disease ◽  
Systemic Acquired Resistance ◽  
Field Experiments ◽  
Specific Resistance ◽  
Acquired Resistance ◽  
R Genes ◽  
Host Pathogen Interaction ◽  
Major Resistance Genes

The lack of durability of host plant disease resistance is a major problem in disease control. Genotype-specific resistance that involves major resistance (R) genes is especially prone to failure. The compatible (i.e., disease) host-pathogen interaction with systemic acquired resistance (SAR) has been studied extensively, but the incompatible (i.e., resistant) interaction less so. Using the pepper-bacterial spot (causal agent, Xanthomonas axonopodis pv. vesicatoria) pathosystem, we examined the effect of SAR in reducing the occurrence of race-change mutants that defeat R genes in laboratory, greenhouse, and field experiments. Pepper plants carrying one or more R genes were sprayed with the plant defense activator acibenzolar-S-methyl (ASM) and challenged with incompatible strains of the pathogen. In the greenhouse, disease lesions first were observed 3 weeks after inoculation. ASM-treated plants carrying a major R gene had significantly fewer lesions caused by both the incompatible (i.e., hypersensitive) and compatible (i.e., disease) responses than occurred on nonsprayed plants. Bacteria isolated from the disease lesions were confirmed to be race-change mutants. In field experiments, there was a delay in the detection of race-change mutants and a reduction in disease severity. Decreased disease severity was associated with a reduction in the number of race-change mutants and the suppression of disease caused by the race-change mutants. This suggests a possible mechanism related to a decrease in the pathogen population size, which subsequently reduces the number of race-change mutants for the selection pressure of R genes. Thus, inducers of SAR are potentially useful for increasing the durability of genotype-specific resistance conferred by major R genes.

scholarly journals Biological and Molecular Analyses of the Acibenzolar-S-Methyl-Induced Systemic Acquired Resistance in Flue-Cured Tobacco Against Tomato spotted wilt virus

2008 ◽  
Vol 98 (2) ◽  
pp. 196-204 ◽  
Author(s):  
B. Mandal ◽  
S. Mandal ◽  
A. S. Csinos ◽  
N. Martinez ◽  
A. K. Culbreath ◽  
...  
Keyword(s):  
Tomato Spotted Wilt Virus ◽  
Systemic Acquired Resistance ◽  
Field Experiments ◽  
Acquired Resistance ◽  
Systemic Infection ◽  
Inverse Correlation ◽  
Challenge Inoculation ◽  
Tomato Spotted Wilt ◽  
High Level ◽  
Wilt Virus

Tomato spotted wilt virus (TSWV) is an economically important virus of flue-cured tobacco. Activation of systemic acquired resistance (SAR) by acibenzolar-S-methyl (ASM) in flue-cured tobacco was studied under greenhouse conditions by challenge inoculation with a severe isolate of TSWV. ASM restricted virus replication and movement, and as a result reduced systemic infection. Activation of resistance was observed within 2 days after treatment with ASM and a high level of resistance was observed at 5 days onward. Expression of the pathogenesis-related (PR) protein gene, PR-3, and different classes of PR proteins such as PR-1, PR-3, and PR-5 were detected at 2 days post-ASM treatment which inversely correlated with the reduction in the number of local lesions caused by TSWV. Tobacco plants treated with increased quantities of ASM (0.25, 0.5, 1.0, 2.0, and 4.0 g a.i./7,000 plants) showed increased levels of SAR as indicated by the reduction of both local and systemic infections by TSWV. The highest level of resistance was at 4 g a.i., but this rate of ASM also caused phytotoxicity resulting in temporary foliar spotting and stunting of plants. An inverse correlation between the TSWV reduction and phytotoxicity was observed with the increase of ASM concentration. ASM at the rate of 1 to 2 g a.i./7,000 plants activated a high level of resistance and minimized the phytotoxicity. Use of gibberellic acid in combination with ASM reduced the stunting caused by ASM. Present findings together with previous field experiments demonstrate that ASM is a potential option for management of TSWV in flue-cured tobacco.

scholarly journals The effect of Regalis® (prohexadione calcium) on the reduction of fire blight (Erwinia amylovora) severity in apple trees

2004 ◽  
Vol 10 (2) ◽  
Author(s):  
P. Sobiczewski ◽  
T. Bubán
Keyword(s):  
Active Ingredient ◽  
Fire Blight ◽  
Shoot Growth ◽  
Control Strategies ◽  
Fruit Trees ◽  
Pome Fruit ◽  
Apple Trees ◽  
Obvious Effect ◽  
One Year ◽  
Prohexadione Calcium

Due to the lack of effective and non-phytotoxic materials for control of the blossom and shoot blight phase of fire blight in pome fruit trees, two novel control strategies have emerged: shoot growth retardation by bioregulators and applying resistance inducer compounds. Prohexadione calcium (ProCa) is the active ingredient of the bioregulator Regalis® registered in several European countries. The reduction of shoot growth elongation is the most obvious effect of ProCa. Furthermore, it causes significant changes in the spectrum of flavonoids and their phenolic precursors, leading to the considerable reduction of susceptibility to fire blight. In Poland, potted one-year-old apple trees of cvs. Gala Must grafted on M.26 and Sampion on M.9 (in 2001) as well as Gala Must on P.60 (in 2002) were treated with Regalis® at a range of concentration of 250, 150 or 150 + 100 ppm, respectively. The inoculation of shoots was made with the strain No.691 of E. amylovora (107 cfu/ml), on the 7th and 21st'day after treatments with Regalis. In Hungary, during the years of 2002 and 2003 one-year-old container grown apple trees of the cvs. Idared/M.9 and Freedom/M.9 were treated with the prohexadione-Ca, the active ingredient of Regalis® 100, 150 or 200 ppm, two weeks before inoculation with the Ea 1 strain of E. amylovora (107 cfu/m1). In Poland, the suppression of fire blight in shoots reached up to 80%, depending on concentration and application time of Regalis®. In Hungary, the effect of prohexadione-Ca treatments, determined by the length of necrotic lesion developed, proved to be better than that of streptomycin used for comparison.

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