scholarly journals Infection with Rhizoctonia solani Induces Defense Genes and Systemic Resistance in Potato Sprouts Grown Without Light

2008 ◽  
Vol 98 (11) ◽  
pp. 1190-1198 ◽  
Author(s):  
M. J. Lehtonen ◽  
P. Somervuo ◽  
J. P. T. Valkonen
Keyword(s):  
Rhizoctonia Solani ◽  
Secondary Infection ◽  
Quantitative Polymerase Chain Reaction ◽  
Systemic Resistance ◽  
Pathogen Defense ◽  
Systemic Induction ◽  
Challenge Inoculation ◽  
Apical Portion ◽  
Significant Damage ◽  
Basal Portion

Rhizoctonia solani is an important soilborne and seedborne fungal pathogen of potato (Solanum tuberosum). The initial infection of sprouts prior to emergence causes lesions and may be lethal to the sprout or sprout tip, which results in initiation and compensatory growth of new sprouts. They emerge successfully and do not suffer significant damage. The mechanism behind this recovery phenomenon is not known. It was hypothesized that infection may induce pathogen defense in sprouts, which was investigated in the present study. Tubers were sprouted in cool and moist conditions in darkness to mimic conditions beneath soil. The basal portion of the sprout was isolated from the apical portion with a soft plastic collar and inoculated with highly virulent R. solani. Induction of defense-related responses was monitored in the apical portion using microarray and quantitative polymerase chain reaction techniques at 48 and 120 h postinoculation (hpi) and by challenge-inoculation with R. solani in two experiments. Differential expression of 122 and 779 genes, including many well-characterized defense-related genes, was detected at 48 and 120 hpi, respectively. The apical portion of the sprout also expressed resistance which inhibited secondary infection of the sprouts. The observed systemic induction of resistance in sprouts upon infection with virulent R. solani provides novel information about pathogen defense in potato before the plant emerges and becomes photosynthetically active. These results advance our understanding of the little studied subject of pathogen defense in subterranean parts of plants.

scholarly journals Systemic Induction of Peroxidases, 1,3-β-Glucanases, Chitinases, and Resistance in Bean Plants by Binucleate Rhizoctonia Species

1998 ◽  
Vol 88 (4) ◽  
pp. 359-365 ◽  
Author(s):  
L. Xue ◽  
P. M. Charest ◽  
S. H. Jabaji-Hare
Keyword(s):  
Rhizoctonia Solani ◽  
Disease Severity ◽  
Root Rot ◽  
Induced Systemic Resistance ◽  
Colletotrichum Lindemuthianum ◽  
Systemic Resistance ◽  
Systemic Induction ◽  
Binucleate Rhizoctonia ◽  
Bean Plants ◽  
And Control

Inoculation of bean hypocotyls with a nonpathogenic binucleate Rhizoctonia (BNR) species induced systemic resistance and protection of the roots and cotyledons to later challenge with the root rot pathogen Rhizoctonia solani or the anthracnose pathogen Colletotrichum lindemuthianum. Bean seedlings that were treated with BNR 48 h prior to their challenge with R. solani or C. lindemuthianum had few necrotic lesions and reduced disease severity as compared with seedlings not treated with BNR. Treatment with BNR 48 h prior to their challenge also elicited a significant and systemic increase in all cellular fractions of peroxidases, 1,3-β-glucanases, and chitinases compared with the diseased and control plants. Compared with control plants, total peroxidases and glucanases increased twofold and eightfold, respectively, in all protected bean tissues. BNR 232-CG could not be recovered from the challenged hypocotyls or cotyledons, indicating that there was no contact between the inducer and the pathogen. Both the 1,3-β-glucanases and the peroxidases were positively correlated with induced resistance.

scholarly journals Bacillus cereus AR156 Activates Defense Responses to Pseudomonas syringae pv. tomato in Arabidopsis thaliana Similarly to flg22

2018 ◽  
Vol 31 (3) ◽  
pp. 311-322 ◽  
Author(s):  
Shune Wang ◽  
Ying Zheng ◽  
Chun Gu ◽  
Chan He ◽  
Mengying Yang ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
Bacillus Cereus ◽  
Pseudomonas Syringae ◽  
Transcriptional Profiling ◽  
Quantitative Polymerase Chain Reaction ◽  
Polymerase Chain Reaction Analysis ◽  
Defense Responses ◽  
Systemic Resistance ◽  
Callose Deposition ◽  
Plant Growth Promoting

Bacillus cereus AR156 (AR156) is a plant growth–promoting rhizobacterium capable of inducing systemic resistance to Pseudomonas syringae pv. tomato in Arabidopsis thaliana. Here, we show that, when applied to Arabidopsis leaves, AR156 acted similarly to flg22, a typical pathogen-associated molecular pattern (PAMP), in initiating PAMP-triggered immunity (PTI). AR156-elicited PTI responses included phosphorylation of MPK3 and MPK6, induction of the expression of defense-related genes PR1, FRK1, WRKY22, and WRKY29, production of reactive oxygen species, and callose deposition. Pretreatment with AR156 still significantly reduced P. syringae pv. tomato multiplication and disease severity in NahG transgenic plants and mutants sid2-2, jar1, etr1, ein2, npr1, and fls2. This suggests that AR156-induced PTI responses require neither salicylic acid, jasmonic acid, and ethylene signaling nor flagella receptor kinase FLS2, the receptor of flg22. On the other hand, AR156 and flg22 acted in concert to differentially regulate a number of AGO1-bound microRNAs that function to mediate PTI. A full-genome transcriptional profiling analysis indicated that AR156 and flg22 activated similar transcriptional programs, coregulating the expression of 117 genes; their concerted regulation of 16 genes was confirmed by real-time quantitative polymerase chain reaction analysis. These results suggest that AR156 activates basal defense responses to P. syringae pv. tomato in Arabidopsis, similarly to flg22.

scholarly journals Induced Systemic Resistance in Arabidopsis thaliana Against Pseudomonas syringae pv. tomato by 2,4-Diacetylphloroglucinol-Producing Pseudomonas fluorescens

2012 ◽  
Vol 102 (4) ◽  
pp. 403-412 ◽  
Author(s):  
David M. Weller ◽  
Dmitri V. Mavrodi ◽  
Johan A. van Pelt ◽  
Corné M. J. Pieterse ◽  
Leendert C. van Loon ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
Pseudomonas Fluorescens ◽  
Induced Resistance ◽  
Pseudomonas Syringae ◽  
Induced Systemic Resistance ◽  
Signal Transduction Pathway ◽  
Systemic Resistance ◽  
Wild Type ◽  
Challenge Inoculation ◽  
Dependent Signal

Pseudomonas fluorescens strains that produce the polyketide antibiotic 2,4-diacetylphloroglucinol (2,4-DAPG) are among the most effective rhizobacteria that suppress root and crown rots, wilts, and damping-off diseases of a variety of crops, and they play a key role in the natural suppressiveness of some soils to certain soilborne pathogens. Root colonization by 2,4-DAPG-producing P. fluorescens strains Pf-5 (genotype A), Q2-87 (genotype B), Q8r1-96 (genotype D), and HT5-1 (genotype N) produced induced systemic resistance (ISR) in Arabidopsis thaliana accession Col-0 against bacterial speck caused by P. syringae pv. tomato. The ISR-eliciting activity of the four bacterial genotypes was similar, and all genotypes were equivalent in activity to the well-characterized strain P. fluorescens WCS417r. The 2,4-DAPG biosynthetic locus consists of the genes phlHGF and phlACBDE. phlD or phlBC mutants of Q2-87 (2,4-DAPG minus) were significantly reduced in ISR activity, and genetic complementation of the mutants restored ISR activity back to wild-type levels. A phlF regulatory mutant (overproducer of 2,4-DAPG) had ISR activity equivalent to the wild-type Q2-87. Introduction of DAPG into soil at concentrations of 10 to 250 μM 4 days before challenge inoculation induced resistance equivalent to or better than the bacteria. Strain Q2-87 induced resistance on transgenic NahG plants but not on npr1-1, jar1, and etr1 Arabidopsis mutants. These results indicate that the antibiotic 2,4-DAPG is a major determinant of ISR in 2,4-DAPG-producing P. fluorescens, that the genotype of the strain does not affect its ISR activity, and that the activity induced by these bacteria operates through the ethylene- and jasmonic acid-dependent signal transduction pathway.

scholarly journals The Plant Growth–Promoting Rhizobacterium Bacillus cereus AR156 Induces Systemic Resistance in Arabidopsis thaliana by Simultaneously Activating Salicylate- and Jasmonate/Ethylene-Dependent Signaling Pathways

2011 ◽  
Vol 24 (5) ◽  
pp. 533-542 ◽  
Author(s):  
Dong-Dong Niu ◽  
Hong-Xia Liu ◽  
Chun-Hao Jiang ◽  
Yun-Peng Wang ◽  
Qing-Ya Wang ◽  
...  
Keyword(s):  
Plant Growth ◽  
Bacillus Cereus ◽  
Signaling Pathways ◽  
Pseudomonas Syringae ◽  
Defense Responses ◽  
Systemic Resistance ◽  
Dependent Manner ◽  
Challenge Inoculation ◽  
Plant Growth Promoting ◽  
Growth Promoting

Bacillus cereus AR156 is a plant growth–promoting rhizobacterium that induces resistance against a broad spectrum of pathogens including Pseudomonas syringae pv. tomato DC3000. This study analyzed AR156-induced systemic resistance (ISR) to DC3000 in Arabidopsis ecotype Col-0 plants. Compared with mock-treated plants, AR156-treated ones showed an increase in biomass and reductions in disease severity and pathogen density in the leaves. The defense-related genes PR1, PR2, PR5, and PDF1.2 were concurrently expressed in the leaves of AR156-treated plants, suggesting simultaneous activation of the salicylic acid (SA)- and the jasmonic acid (JA)- and ethylene (ET)-dependent signaling pathways by AR156. The above gene expression was faster and stronger in plants treated with AR156 and inoculated with DC3000 than that in plants only inoculated with DC3000. Moreover, the cellular defense responses hydrogen peroxide accumulation and callose deposition were induced upon challenge inoculation in the leaves of Col-0 plants primed by AR156. Also, pretreatment with AR156 led to a higher level of induced protection against DC3000 in Col-0 than that in the transgenic NahG, the mutant jar1 or etr1, but the protection was absent in the mutant npr1. Therefore, AR156 triggers ISR in Arabidopsis by simultaneously activating the SA- and JA/ET-signaling pathways in an NPR1-dependent manner that leads to an additive effect on the level of induced protection.

scholarly journals Redox-Active Pyocyanin Secreted by Pseudomonas aeruginosa 7NSK2 Triggers Systemic Resistance to Magnaporthe grisea but Enhances Rhizoctonia solani Susceptibility in Rice

2006 ◽  
Vol 19 (12) ◽  
pp. 1406-1419 ◽  
Author(s):  
David De Vleesschauwer ◽  
Pierre Cornelis ◽  
Monica Höfte
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Rhizoctonia Solani ◽  
Magnaporthe Grisea ◽  
Root Surface ◽  
Sheath Blight ◽  
Blast Disease ◽  
Systemic Resistance ◽  
Sodium Ascorbate ◽  
In Planta ◽  
Pyocyanin Production

Pseudomonas aeruginosa 7NSK2 induces resistance in dicots through a synergistic interaction of the phenazine pyocyanin and the salicylic acid-derivative pyochelin. Root inoculation of the monocot model rice with 7NSK2 partially protected leaves against blast disease (Magnaporthe grisea) but failed to consistently reduce sheath blight (Rhizoctonia solani). Only mutations interfering with pyocyanin production led to a significant decrease in induced systemic resistance (ISR) to M. grisea, and in trans complementation for pyocyanin production restored the ability to elicit ISR. Intriguingly, pyocyanin-deficient mutants, unlike the wild type, triggered ISR against R. solani. Hence, bacterial pyocyanin plays a differential role in 7NSK2-mediated ISR in rice. Application of purified pyocyanin to hydroponically grown rice seedlings increased H2O2 levels locally on the root surface as well as a biphasic H2O2 generation pattern in distal leaves. Co-application of pyocyanin and the antioxidant sodium ascorbate alleviated the opposite effects of pyocyanin on rice blast and sheath blight development, suggesting that the differential effectiveness of pyocyanin with respect to 7NSK2-triggered ISR is mediated by transiently elevated H2O2 levels in planta. The cumulative results suggest that reactive oxygen species act as a double-edged sword in the interaction of rice with the hemibiotroph M. grisea and the necrotroph R. solani.

A NEW HAPLOPTILIA WITH NOTES ON TWO OTHER SPECIES (LEPID)

1936 ◽  
Vol 68 (3) ◽  
pp. 52-55 ◽  
Author(s):  
J. McDunnough
Keyword(s):  
Apical Portion ◽  
Basal Portion ◽  
As If

In the middle of June, 1934, while spending a few days at Annapolis Royal. N. S., I collected some Haploptilia cases of the pruniella type from the foliage of Kalvnia. Half a dozen or so of these cases were attached to the upper-side of the previous year's leaves; they were dull gray-brown in color and the apical portion was noticeably weather-worn as if the cases had hibernated; there was no sign that living larvae were within them as they remained perfectly quiescent on the leaves. A few other cases, found at the same time, showed evidence that living larvae were still within; these cases were brighter brown in color and appeared to have been more recently constructed as the apical portions showed clearly the smaller cases of one, and sonletimes two, previous instars, attached in the usual holster-like manner to the much larger and broader basal portion. These latter larvae crawled about in the receptacle and fed slightly but soon in their turn became quiescent. The accompanying figures give some idea of the two forms of cases.

scholarly journals First Report of Pratylenchus fallax on Turfgrass in Ontario

Plant Disease ◽  
1997 ◽  
Vol 81 (11) ◽  
pp. 1331-1331
Author(s):  
Q. Yu ◽  
J. W. Potter ◽  
G. A. Gilby
Keyword(s):  
Main Type ◽  
Poa Pratensis ◽  
Secondary Infection ◽  
Mature Female ◽  
Parasitic Nematodes ◽  
Golf Courses ◽  
Plant Parasitic Nematodes ◽  
First Report ◽  
Corn Roots ◽  
Significant Damage

During 1995 and 1997 surveys of golf courses throughout southern Ontario for plant parasitic nematodes, one Pratylenchus sp. with a heavily sclerotized cephalic area, lip region with three annules, females with spermatheca full of sperms, and crenate tail was found in 13 of 14 soil samples taken from fairways. Males were also found in the samples. Monoxenic cultures of the nematode were established on excised corn roots, each culture started from a single mature female. In cultures, males were common, averaging about one male per five females. Following a comparative microscope study of about 50 specimens (20 measured), the species was identified as Pratylenchus fallax Seinhorst, 1968. Bluegrass (Poa pratensis L.) was the main type of grass in the fairways surveyed. P. fallax may cause significant damage to turfgrass by directly destroying the roots, and the wounded roots become vulnerable to secondary infection by soilborne pathogens (1). The nematode has been found once in Quebec, Canada, in 1976 (2). This is the first report of Pratylenchus fallax in Ontario. References: (1) S. G. Fushtey and F. D. McElroy. Can. Plant Dis. Surv. 57:54, 1977. (2) P. W. Willis et al. Plant Dis. Rep. 60:207, 1976.

First record of tiger beetles (Coleoptera, Cicindelidae) from Rovno amber, with the description of a new genus and species

Zootaxa ◽  
2021 ◽  
Vol 5016 (2) ◽  
pp. 243-256
Author(s):  
ANDREY V. MATALIN ◽  
EVGENY E. PERKOVSKY ◽  
DMITRY V. VASILENKO
Keyword(s):  
New Genus ◽  
First Record ◽  
Rovno Amber ◽  
New Genus And Species ◽  
Apical Portion ◽  
Tiger Beetle ◽  
Tiger Beetles ◽  
Probable Presence ◽  
Basal Portion ◽  
Fossil Resins

A new fossil tiger beetle species, Goriresina fungifora gen. n., sp. n. (Coleoptera, Cicindelidae), is described from Eocene Rovno amber. The new genus belongs to the subtribe Iresiina, tribe Cicindelini, due to the glabrous head, the labrum with six submarginal setae (latero-basal setae very long) and two apical teeth with notch between them, the glabrous and globular pronotum, the lack of setae on the metepisternum and metepimeron, as well as on the visible parts of abdominal sternites, the single long seta each on the fore- and mesotrochanter. The new species is characterized by the long and moderately convex labrum, two clypeal setae, the elongate and apicad converging elytra with an angularly, but smoothly rounded apex, the small and sharp sutural spine, the probable presence of an apical portion of the elytral humeral spot, a slightly sinuate, transverse medial fascia with an extended and downward directed apical portion, and a slightly transverse basal portion of the apical spot. This is the first record of a tiger beetle in Rovno amber and only a fourth well-preserved Cicindelidae from fossil resins.  

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