Expression of the Phytophthora infestans ipiB and ipi0 genes in planta and in vitro

Phytophthora infestans causes late blight of potato, one of the most devastating diseases affecting potato production. Alternative approaches for controlling late blight are being increasingly sought due to increasing environmental concerns over the use of chemical pesticides and the increasing resistance of P. infestans to fungicides. Our research group has isolated a new strain of Pseudomonas fluorescens (LBUM636) of biocontrol interest producing the antibiotic phenazine-1-carboxylic acid (PCA). Wild-type LBUM636 was shown to significantly inhibit the growth of Phytophthora infestans in in vitro confrontational assays whereas its isogenic mutant (phzC−; not producing PCA) only slightly altered the pathogen’s growth. Wild-type LBUM636 but not the phzC− mutant also completely repressed disease symptom development on tubers. A pot experiment revealed that wild-type LBUM636 can significantly reduce P. infestans populations in the rhizosphere and in the roots of potato plants, as well as reduce in planta disease symptoms due to PCA production. The expression of eight common plant defense-related genes (ChtA, PR-1b, PR-2, PR-5, LOX, PIN2, PAL-2, and ERF3) was quantified in tubers, roots, and leaves by reverse-transcription quantitative polymerase chain reaction and revealed that the biocontrol observed was not associated with the induction of a plant defense response by LBUM636. Instead, a direct interaction between P. infestans and LBUM636 is required and PCA production appears to be a key factor for LBUM636’s biocontrol ability.

Download Full-text

Broad-spectrum inhibition of Phytophthora infestans by root endophytes

10.1101/107052 ◽

2017 ◽

Author(s):

Sophie de Vries ◽

Janina K. von Dahlen ◽

Anika Schnake ◽

Sarah Ginschel ◽

Barbara Schulz ◽

...

Keyword(s):

Phytophthora Infestans ◽

Broad Spectrum ◽

Biocontrol Agent ◽

Agar Medium ◽

Fungal Endophytes ◽

Effective Control ◽

Bioactive Metabolites ◽

List Type ◽

In Planta

SummaryPhytophthora infestans (Phy. infestans) is a devastating pathogen of tomato and potato. It readily overcomes resistance genes and applied agrochemicals. Fungal endophytes provide a largely unexplored avenue of control against Phy. infestans. Not only do endophytes produce a wide array of bioactive metabolites, they may also directly compete with and defeat pathogens in planta.Twelve isolates of fungal endophytes from different plant species were tested in vitro for their production of metabolites with anti-Phy. infestans activity. Four well-performing isolates were evaluated for their ability to suppress nine isolates of Phy. infestans on agar medium and in planta.Two endophytes reliably inhibited all Phy. infestans isolates on agar medium, of which Phoma eupatorii isolate 8082 was the most promising. It nearly abolished infection by Phy. infestans in planta.Here we present a biocontrol agent, which can inhibit a broad-spectrum of Phy. infestans isolates. Such broadly acting inhibition is ideal, because it allows for effective control of genetically diverse pathogen isolates and may slow the adaptation of Phy. infestans.

Download Full-text

Mutagenesis of Phytophthora infestans for Resistance Against Carboxylic Acid Amide and Phenylamide Fungicides

Plant Disease ◽

10.1094/pdis-92-5-0675 ◽

2008 ◽

Vol 92 (5) ◽

pp. 675-683 ◽

Cited By ~ 20

Author(s):

Avia (Evgenia) Rubin ◽

Dror Gotlieb ◽

Ulrich Gisi ◽

Yigal Cohen

Keyword(s):

Carboxylic Acid ◽

Phytophthora Infestans ◽

Mating Type ◽

Uv Light ◽

Acid Amide ◽

Late Blight Resistance ◽

Plasmopara Viticola ◽

Carboxylic Acid Amide ◽

In Planta

The carboxylic acid amide (CAA) fungicides mandipropamid, dimethomorph, iprovalicarb, and the phenylamide fungicide mefenoxam (MFX, the active enantiomer of metalaxyl) are anti-oomycete fungicides effective against downy mildews and late blight. Resistance against MFX was reported in nature in several oomycetes including Phytophthora infestans and Plasmopara viticola, whereas resistance against CAAs was reported in P. viticola but not in P. infestans. In this study the mutability of P. infestans for resistance against CAAs and MFX (as a control) was explored under laboratory conditions. UV light or chemical mutagens (e.g., ethyl methan sulfonate [EMS]) were applied to sporangia, and the emergence of mutants resistant to CAAs or MFX, or with altered mating type, was followed. Many mutants resistant to CAAs developed at generation 0 after mutagenesis, but all showed erratic, instable resistance in planta, diminishing after 1 to 8 asexual infection cycles, and failed to grow on CAA-amended medium. In contrast, 19 mutants resistant to MFX were obtained: 6 with UV irradiation (in isolates 28 or 96) and 13 with EMS (in isolates 408, 409, and 410). In three experiments, a shift in mating type, from A1 to A2, was detected. To elucidate whether or not resistance to CAAs is recessive and therefore might emerge only after sexual recombination, A1 and A2 mutants were crossed and the F1 and F2 progeny isolates were tested for resistance. Offspring isolates segregated for resistance to MFX, with resistant isolates maintaining stable resistance in vitro and in planta, whereas all progeny isolates failed to show stable resistance to CAAs in planta or in vitro. The data suggest that P. infestans could be artificially mutated for resistance against MFX, but not against CAAs.

Download Full-text

Oospore Survival and Pathogenicity of Single Oospore Recombinant Progeny from a Cross Involving US-17 and US-8 Genotypes of Phytophthora infestans

Plant Disease ◽

10.1094/pdis.2000.84.11.1190 ◽

2000 ◽

Vol 84 (11) ◽

pp. 1190-1196 ◽

Cited By ~ 49

Author(s):

H. Mayton ◽

C. D. Smart ◽

B. C. Moravec ◽

E. S. G. Mizubuti ◽

A. E. Muldoon ◽

...

Keyword(s):

Phytophthora Infestans ◽

Restriction Fragment ◽

Fragment Length ◽

Field Conditions ◽

In Planta ◽

Natural Field ◽

Length Polymorphisms ◽

Parental Isolate ◽

Restriction Fragment Length

Oospores of Phytophthora infestans produced in vitro and in planta, from a cross between US-17 and US-8 genotypes, were exposed to a variety of environments and their survival was assessed. Additionally, the pathogenic characteristics of some resultant progeny isolates were assessed. Viability of oospores as measured by plasmolysis declined slightly over a period of 18 months whether they were stored in water at 4°C, in soil at 18°C, or in soil under natural field conditions. In comparison, viability as measured by germination was lower overall but appeared to increase after storage in soil. Oospores produced in planta were buried in the field in the fall of 1998, and were capable of infecting both tomato and potato leaflets when recovered in May 1999. Single oospore progeny (n = 53) from the in vitro cross were analyzed individually for genetic and pathogenicity characteristics. All 53 progeny tested for restriction fragment length polymorphisms with probe RG57 were hybrids. All but one progeny produced sporulating lesions on detached potato or tomato leaflets in growth chamber tests, but most lesions were smaller and developed more slowly than those produced by either parental isolate. In a further test of pathogenicity, under field conditions, none of a subset of 10 A2 progeny was capable of initiating a detectable epidemic in small plots of either potatoes or tomatoes.

Download Full-text

A Gene Encoding a Protein Elicitor of Phytophthora infestans Is Down-Regulated During Infection of Potato

Molecular Plant-Microbe Interactions ◽

10.1094/mpmi.1997.10.1.13 ◽

1997 ◽

Vol 10 (1) ◽

pp. 13-20 ◽

Cited By ~ 165

Author(s):

Sophien Kamoun ◽

Pieter van West ◽

Anke J. de Jong ◽

Koen E. de Groot ◽

Vivianne G. A. A. Vleeshouwers ◽

...

Keyword(s):

Phytophthora Infestans ◽

Culture Media ◽

Solanum Species ◽

In Planta ◽

Gene Encoding ◽

Protein Elicitor ◽

Solanaceous Plants ◽

Solanaceae Family

Most species of the genus Phytophthora produce 10-kDa extracellular protein elicitors, collectively termed elicitins. Elicitins induce hypersensitive response in a restricted number of plants, particularly in the genus Nicotiana within the Solanaceae family. A cDNA encoding INF1, the major secreted elicitin of Phytophthora infestans, a pathogen of solanaceous plants, was isolated and characterized. The expression of the corresponding inf1 gene during the disease cycle of P. infestans was analyzed. inf1 was shown to be expressed in mycelium grown in various culture media, whereas it was not expressed in sporangiospores, zoospores, cysts, and germinating cysts. In planta, during infection of potato, particularly during the biotrophic stage, expression of inf1 was down-regulated compared to in vitro. The highest levels of expression of inf1 were observed in in vitro grown mycelium and in late stages of infection when profuse sporulation and leaf necrosis occur. The potential role of INF1 as an elicitor in interactions between P. infestans and Solanum species was investigated. Nineteen lines, representing nine solanaceous species with various levels of resistance to P. infestans, were tested for response to an Escherichia coli expressed INF1. Within the genus Solanum, resistance to P. infestans did not appear to be mediated by a defense response elicited by INF1. However, INF1 recognition could be a component of nonhost resistance of tobacco to P. infestans.

Download Full-text

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

Plant Physiology ◽

10.1093/plphys/kiab111 ◽

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.

Download Full-text

Zinc phosphate protects tomato plants against Pseudomonas syringae pv. tomato

Journal of Plant Diseases and Protection ◽

10.1007/s41348-021-00444-z ◽

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.

Download Full-text

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

International Journal of Molecular Sciences ◽

10.3390/ijms22147440 ◽

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.

Download Full-text