scholarly journals Incidence and Significance of Iprodione-Insensitive Isolates of Botrytis squamosa

Plant Disease ◽  
2007 ◽  
Vol 91 (1) ◽  
pp. 41-46 ◽  
Author(s):  
O. Carisse ◽  
D. M. Tremblay
Keyword(s):  
Active Ingredient ◽  
Leaf Blight ◽  
Conidial Suspension ◽  
In Planta ◽  
Good Relationship ◽  
Percent Inhibition ◽  
Botrytis Squamosa ◽  
Leaf Lesion ◽  
Important Disease

Botrytis leaf blight, caused by Botrytis squamosa, is an economically important disease of onion. The principal means of controlling the disease is by applying fungicides. Typical fungicide programs include applications of dithiocarbamates, chloronitriles, carboxamides, and dicarboximides such as iprodione (Rovral). Onion fields were surveyed in 2002, 2003, and 2004 for insensitivity to iprodione. Tests for insensitivity to iprodione were conducted on 62, 58, and 60 monoconidial field isolates using the automated quantitative (AQ) method with a discriminatory dose of 1.78 ppm of iprodione active ingredient (a.i.) in 2002, 2003, and 2004, respectively. Overall, insensitive isolates were detected in 51% of the fields, and the proportions of insensitive isolates were 8.1, 20.7, and 18.3% in 2002, 2003, and 2004, respectively. The aggressiveness of 10 insensitive and 18 sensitive isolates and the efficacy of iprodione was tested in planta. Onion leaves were inoculated with 750 μl of a conidial suspension of 75,000 conidia per ml and incubated in a growth chamber at 15°C. Aggressiveness was measured as lesion density (average number of lesions per cm2 of onion leaf). Lesion density varied from 2.82 to 8.04 lesions per cm2 of leaf. There was a significant effect (P < 0.0001) of isolates on lesion density. However, there was no significant correlation between lesion density and sensitivity to iprodione (r = 0.08). When onion leaves were sprayed with 1,875, 3,750, and 7,500 ppm of iprodione, percent inhibition of lesion density was higher for sensitive isolates with means of 43.04, 61.42, and 74.59, respectively. Accordingly, percent inhibition was lower for insensitive isolates with means of 13.81, 28.26, and 44.37 for iprodione concentrations of 1,875, 3,750, and 7,500, respectively. It was concluded that the incidence of insensitive isolates was relatively low, but insensitive isolates were capable of infecting onion leaves. There was a good relationship between insensitivity to iprodione in B. squamosa populations measured in vitro with the AQ method, and the reduced efficacy of iprodione in controlling Botrytis leaf blight.

scholarly journals Antagonisme Bacillus terhadap Infeksi Layu Fusarium pada Bibit Pisang Hasil Kultur Jaringan

2013 ◽  
Vol 15 (1) ◽  
pp. 21
Author(s):  
Hadiwiyono Hadiwiyono ◽  
Arief Widyantoro ◽  
Salim Widono
Keyword(s):  
Biological Control ◽  
Fusarium Oxysporum ◽  
Fusarium Wilt ◽  
In Planta ◽  
Physiological Character ◽  
Important Disease

<p>Fusarium wilt (Fusarium oxysporum f.sp. cubense) is an important disease in banana. Fusarium wilt was hard to control because the pathogen can survive in many kind of soils type although there is no host. Therefore, overcoming the disease is urgently needed such as biological control. The endophytic Bacillus of banana was begun to use as antagonist agent to the pathogen. This research aimed to study the mechanism of antagonism and physiological character of Bacillus. There were 27 Bacillus isolates examined in-vitro to test the production of IAA, HCN, chitinase, pectinase, and antagonism. The top ten isolates based on the test in vitro were used to test in planta. The research showed that Bacillus were able to produce IAA, HCN, chitinase, pectinase, and able to retard the growth of Foc colony. The application of isolat B25 on banana seedling could decrease the disease intensity but still unable to prevent the fusarium wilt infection.</p>

scholarly journals Effect of temperature and photoperiod on the in vitro germination of conidia of Botrytis squamosa, the causal agent of Botrytis leaf blight of onion

2016 ◽  
Vol 42 (3) ◽  
pp. 261-263 ◽  
Author(s):  
Leandro Luiz Marcuzzo ◽  
Katiani Eli
Keyword(s):  
Optical Microscope ◽  
Germination Percentage ◽  
Leaf Blight ◽  
Causal Agent ◽  
Control Measures ◽  
Effect Of Temperature ◽  
Botrytis Squamosa ◽  
Randomized Design ◽  
Petri Dishes

ABSTRACT Temperature and photoperiod have a direct effect on spore germination and, for Botrytis squamosa, there is scare information on this subject. Learning the biology of the causal agent has a great importance to understand the development of the disease in the field, as well to take control measures. With the aim of evaluating the influence of temperature and photoperiod on B. squamosa conidial germination, an experiment was conducted in a completely randomized design with four replicates. A 0.1-ml suspension of 1.65x105 conidia per ml was added and spread on Petri dishes containing 1% water-agar. The Petri dishes were placed in BOD incubators adjusted to 10, 15, 20, 25 and 30°C without light, and the percentage of germination of 100 conidia was evaluated under an optical microscope by measuring the germ tube after 24 hours of incubation. In a second moment, this experiment was repeated by incubating the spores at 23°C and photoperiods of 0, 6, 12, 18 and 24 hours, and by evaluating the percentage of germination after 24 hours. Results showed that the highest germination percentages can be obtained in the temperature range between 10 (79.75%) and 30°C (92.5%), and the optimum temperature for germination is 23°C. In relation to photoperiod, the highest germination percentage (94%) was obtained without light, which indicates that B. squamosa germination is favored by shorter periods of light. Thus, the information obtained on the biology of the causal agent of botrytis leaf blight allows better understand the epidemiology of this disease, and such results can be used to help develop a disease forecasting system.

scholarly journals First Report of Leaf Blight and Root and Foot Rot of a Strelitzia Caused by Phytophthora nicotianae in Italy

Plant Disease ◽  
2010 ◽  
Vol 94 (1) ◽  
pp. 134-134 ◽  
Author(s):  
L. Luongo ◽  
M. Galli ◽  
L. Riccioni ◽  
A. Belisario
Keyword(s):  
Leaf Blight ◽  
Phytophthora Nicotianae ◽  
Flowering Plant ◽  
Foot Rot ◽  
In Planta ◽  
Phytophthora Blight ◽  
Tissue Samples ◽  
First Report ◽  
Leaf Spots

Bird of paradise, also known as crane flower (Strelitzia reginae Aiton), is a monocotyledonous flowering plant indigenous to South Africa. It is commonly grown and commercialized as an ornamental plant and it is appreciated for its beautiful flowers. In October of 2008, dark leaf spots and leaf blight associated with a severe root and foot rot were observed on several plants of S. reginae grown in a private garden located in Fiumicino, Italy. Small fragments of tissues (approximately 3 mm) collected from the base of leaves and roots and the margins of brown lesions, previously surface disinfected with 0.5% NaOCl, were plated onto potato dextrose agar (PDA) and incubated at 22°C in the dark. White, web-like, slow-growing colonies with coenocytic mycelium and hyphal swellings consistently developed from all plated tissue samples. Sporangia were ovoid or ellipsoid with prominent papillae (including some bipapillate) and frequently caducous with a short stalk. The dimensions of sporangia were 27 to 64 × 23 to 45 μm (average 43 × 35 μm). Chlamydospores were terminal or intercalary and approximately 30 μm in diameter. Isolates were considered heterothallic because they did not produce gametangia in vitro or in planta. On the basis of morphological features, isolates were identified as Phytophthora nicotianae (Breda de Haan). The identity was confirmed by internal transcribed spacer (ITS) sequence comparison in NCBI database with 99% identity with sequences available in GenBank (e.g., EU331089) and with cytochrome c oxidase subunit I (Cox I) with 99% identity with AY564196 by Kroon et al. (2). The sequences of one isolate, AB177, were deposited in GenBank (Accession Nos. FN430681 and FN552051 for ITS and Cox I, respectively). Pathogenicity tests were conducted in the greenhouse on leaves of a 1-year-old potted S. reginae plant by placing 5-mm-diameter mycelial plugs, cut from the margins of 10-day-old actively growing cultures, with mycelium in contact with plant tissues gently wounded with a needle. Controls were treated as described above, except that PDA sterile plugs were used. Plants were misted with water and placed in sealed plastic bags for 48 h. After 10 days, artificially wounded strelitzia leaves showed lesions (approximately 1 cm long). Controls remained symptomless. All inoculated leaves showed the same leaf symptoms as observed on naturally diseased plants. The pathogen was consistently reisolated from lesions. P. nicotianae has been reported as the causal agent of leaf blight and stem, collar, and root rot on several plants (1). It has been reported as an agent of Phytophthora blight on strelitzia in Japan (3). To our knowledge, this is the first report of P. nicotianae on strelitzia in Italy. References: (1) D. C. Erwin and O. K. Ribeiro. Phytophthora Diseases Worldwide. The American Phytopathological Society, St. Paul, MN, 1996. (2) L. P. N. M. Kroon et al. Fungal Genet. Biol. 41:766, 2004. (3) S. Uematsu et al. Ann. Phytopathol. Soc. Jpn. 60:746, 1994.

scholarly journals Antagonism of the Two-Needle Pine Stem Rust Fungi Cronartium flaccidum and Peridermium pini by Cladosporium tenuissimum In Vitro and In Planta

2001 ◽  
Vol 91 (5) ◽  
pp. 457-468 ◽  
Author(s):  
Salvatore Moricca ◽  
Alessandro Ragazzi ◽  
Keith Richard Mitchelson ◽  
Gemma Assante
Keyword(s):  
Cell Wall ◽  
Spore Wall ◽  
Conidial Suspension ◽  
In Planta ◽  
Pine Seedlings ◽  
Host Cell Wall ◽  
Peridermium Pini ◽  
Hyphal Tip ◽  
Gain Access

Selected isolates of Cladosporium tenuissimum were tested for their ability to inhibit in vitro aeciospore germination of the two-needle pine stem rusts Cronartium flaccidum and Peridermium pini and to suppress disease development in planta. The antagonistic fungus displayed a number of disease-suppressive mechanisms. Aeciospore germination on water agar slides was reduced at 12, 18, and 24 h when a conidial suspension (1.5 × 107 conidia per ml) of the Cladosporium tenuissimum isolates was added. When the aeciospores were incubated in same-strength conidial suspensions for 1, 11, 21, and 31 days, viability was reduced at 20 and 4°C. Light and scanning electron microscopy showed that rust spores were directly parasitized by Cladosporium tenuissimum and that the antagonist had evolved several strategies to breach the spore wall and gain access to the underlying tissues. Penetration occurred with or without appressoria. The hyperparasite exerted a mechanical force to destroy the spore structures (spinules, cell wall) by direct contact, penetrated the aeciospores and subsequently proliferated within them. However, an enzymatic action could also be involved. This was shown by the dissolution of the host cell wall that comes in contact with the mycelium of the mycoparasite, by the lack of indentation in the host wall at the contact site, and by the minimal swelling at the infecting hyphal tip. Culture filtrates of the hyperparasite inhibited germination of rust propagules. A compound purified from the filtrates was characterized by chemical and spectroscopic analysis as cladosporol, a known β-1,3-glucan biosynthesis inhibitor. Conidia of Cladosporium tenuissimum reduced rust development on new infected pine seedlings over 2 years under greenhouse conditions. Because the fungus is an aggressive mycoparasite, produces fungicidal metabolites, and can survive and multiply in forest ecosystems without rusts, it seems a promising agent for the biological control of pine stem rusts in Europe.

scholarly journals A peroxisomal β-oxidative pathway contributes to the formation of C6–C1 aromatic volatiles in poplar

2021 ◽  
Author(s):  
Nathalie D Lackus ◽  
Axel Schmidt ◽  
Jonathan Gershenzon ◽  
Tobias G Köllner
Keyword(s):  
Cinnamic Acid ◽  
Aromatic Compounds ◽  
Populus Trichocarpa ◽  
Alternative Pathway ◽  
Gene Families ◽  
Defense Responses ◽  
In Planta ◽  
Black Cottonwood ◽  
Oxidative Pathway

AbstractBenzenoids (C6–C1 aromatic compounds) play important roles in plant defense and are often produced upon herbivory. Black cottonwood (Populus trichocarpa) produces a variety of volatile and nonvolatile benzenoids involved in various defense responses. However, their biosynthesis in poplar is mainly unresolved. We showed feeding of the poplar leaf beetle (Chrysomela populi) on P. trichocarpa leaves led to increased emission of the benzenoid volatiles benzaldehyde, benzylalcohol, and benzyl benzoate. The accumulation of salicinoids, a group of nonvolatile phenolic defense glycosides composed in part of benzenoid units, was hardly affected by beetle herbivory. In planta labeling experiments revealed that volatile and nonvolatile poplar benzenoids are produced from cinnamic acid (C6–C3). The biosynthesis of C6–C1 aromatic compounds from cinnamic acid has been described in petunia (Petunia hybrida) flowers where the pathway includes a peroxisomal-localized chain shortening sequence, involving cinnamate-CoA ligase (CNL), cinnamoyl-CoA hydratase/dehydrogenase (CHD), and 3-ketoacyl-CoA thiolase (KAT). Sequence and phylogenetic analysis enabled the identification of small CNL, CHD, and KAT gene families in P. trichocarpa. Heterologous expression of the candidate genes in Escherichia coli and characterization of purified proteins in vitro revealed enzymatic activities similar to those described in petunia flowers. RNA interference-mediated knockdown of the CNL subfamily in gray poplar (Populus x canescens) resulted in decreased emission of C6–C1 aromatic volatiles upon herbivory, while constitutively accumulating salicinoids were not affected. This indicates the peroxisomal β-oxidative pathway participates in the formation of volatile benzenoids. The chain shortening steps for salicinoids, however, likely employ an alternative pathway.

scholarly journals POLRMT mutations impair mitochondrial transcription causing neurological disease

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Monika Oláhová ◽  
Bradley Peter ◽  
Zsolt Szilagyi ◽  
Hector Diaz-Maldonado ◽  
Meenakshi Singh ◽  
...  
Keyword(s):  
Progressive External Ophthalmoplegia ◽  
Global Developmental Delay ◽  
Disease Mechanism ◽  
Mitochondrial Transcription ◽  
Functional Studies ◽  
Mtdna Deletions ◽  
Molecular Nature ◽  
Important Disease

AbstractWhile >300 disease-causing variants have been identified in the mitochondrial DNA (mtDNA) polymerase γ, no mitochondrial phenotypes have been associated with POLRMT, the RNA polymerase responsible for transcription of the mitochondrial genome. Here, we characterise the clinical and molecular nature of POLRMT variants in eight individuals from seven unrelated families. Patients present with global developmental delay, hypotonia, short stature, and speech/intellectual disability in childhood; one subject displayed an indolent progressive external ophthalmoplegia phenotype. Massive parallel sequencing of all subjects identifies recessive and dominant variants in the POLRMT gene. Patient fibroblasts have a defect in mitochondrial mRNA synthesis, but no mtDNA deletions or copy number abnormalities. The in vitro characterisation of the recombinant POLRMT mutants reveals variable, but deleterious effects on mitochondrial transcription. Together, our in vivo and in vitro functional studies of POLRMT variants establish defective mitochondrial transcription as an important disease mechanism.

scholarly journals Zinc phosphate protects tomato plants against Pseudomonas syringae pv. tomato

2021 ◽  
Author(s):  
Mara Quaglia ◽  
Marika Bocchini ◽  
Benedetta Orfei ◽  
Roberto D’Amato ◽  
Franco Famiani ◽  
...  
Keyword(s):  
Disease Severity ◽  
Pseudomonas Syringae ◽  
Zinc Phosphate ◽  
Plant Defence ◽  
In Planta ◽  
Tomato Plants ◽  
Pathogenesis Related Protein ◽  
Defence Responses ◽  
Plant Defence Responses

AbstractThe purpose of this study was to determine whether zinc phosphate treatments of tomato plants (Solanum lycopersicum L.) can attenuate bacterial speck disease severity through reduction of Pseudomonas syringae pv. tomato (Pst) growth in planta and induce morphological and biochemical plant defence responses. Tomato plants were treated with 10 ppm (25.90 µM) zinc phosphate and then spray inoculated with strain DAPP-PG 215, race 0 of Pst. Disease symptoms were recorded as chlorosis and/or necrosis per leaf (%) and as numbers of necrotic spots. Soil treatments with zinc phosphate protected susceptible tomato plants against Pst, with reductions in both disease severity and pathogen growth in planta. The reduction of Pst growth in planta combined with significantly higher zinc levels in zinc-phosphate-treated plants indicated direct antimicrobial toxicity of this microelement, as also confirmed by in vitro assays. Morphological (i.e. callose apposition) and biochemical (i.e., expression of salicylic-acid-dependent pathogenesis-related protein PR1b1 gene) defence responses were induced by the zinc phosphate treatment, as demonstrated by histochemical and qPCR analyses, respectively. In conclusion, soil treatments with zinc phosphate can protect tomato plants against Pst attacks through direct antimicrobial activity and induction of morphological and biochemical plant defence responses.

scholarly journals HopA1 Effector from Pseudomonas syringae pv syringae Strain 61 Affects NMD Processes and Elicits Effector-Triggered Immunity

2021 ◽  
Vol 22 (14) ◽  
pp. 7440
Author(s):  
Shraddha K. Dahale ◽  
Daipayan Ghosh ◽  
Kishor D. Ingole ◽  
Anup Chugani ◽  
Sang Hee Kim ◽  
...  
Keyword(s):  
Pseudomonas Syringae ◽  
Disease Susceptibility ◽  
Null Mutant ◽  
In Planta ◽  
Host Range Expansion ◽  
Unique System ◽  
Effector Triggered Immunity ◽  
Transcriptomic Changes ◽  
Immune Detection

Pseudomonas syringae-secreted HopA1 effectors are important determinants in host range expansion and increased pathogenicity. Their recent acquisitions via horizontal gene transfer in several non-pathogenic Pseudomonas strains worldwide have caused alarming increase in their virulence capabilities. In Arabidopsis thaliana, RESISTANCE TO PSEUDOMONAS SYRINGAE 6 (RPS6) gene confers effector-triggered immunity (ETI) against HopA1pss derived from P. syringae pv. syringae strain 61. Surprisingly, a closely related HopA1pst from the tomato pathovar evades immune detection. These responsive differences in planta between the two HopA1s represents a unique system to study pathogen adaptation skills and host-jumps. However, molecular understanding of HopA1′s contribution to overall virulence remain undeciphered. Here, we show that immune-suppressive functions of HopA1pst are more potent than HopA1pss. In the resistance-compromised ENHANCED DISEASE SUSCEPTIBILITY 1 (EDS1) null-mutant, transcriptomic changes associated with HopA1pss-elicited ETI are still induced and carry resemblance to PAMP-triggered immunity (PTI) signatures. Enrichment of HopA1pss interactome identifies proteins with regulatory roles in post-transcriptional and translational processes. With our demonstration here that both HopA1 suppress reporter-gene translations in vitro imply that the above effector-associations with plant target carry inhibitory consequences. Overall, with our results here we unravel possible virulence role(s) of HopA1 in suppressing PTI and provide newer insights into its detection in resistant plants.

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