scholarly journals Persistence of the Host-Selective Toxin Ptr ToxB in the Apoplast

2015 ◽  
Vol 28 (10) ◽  
pp. 1082-1090 ◽  
Author(s):  
Melania Figueroa ◽  
Viola A. Manning ◽  
Iovanna Pandelova ◽  
Lynda M. Ciuffetti
Keyword(s):  
Tan Spot ◽  
In Vitro Assays ◽  
Hydraulic Pressure ◽  
Wheat Cultivars ◽  
Symptom Development ◽  
In Planta ◽  
Pyrenophora Tritici Repentis ◽  
Apoplastic Fluid ◽  
Development In Vitro

The necrotrophic fungus Pyrenophora tritici-repentis is responsible for the disease tan spot of wheat. Ptr ToxB (ToxB), a proteinaceous host-selective toxin, is one of the effectors secreted by P. tritici-repentis. ToxB induces chlorosis in toxin-sensitive wheat cultivars and displays characteristics common to apoplastic effectors. We addressed the hypothesis that ToxB exerts its activity extracellularly. Our data indicate that hydraulic pressure applied in the apoplast following ToxB infiltration can displace ToxB-induced symptoms. In addition, treatment with a proteolytic cocktail following toxin infiltration results in reduction of symptom development and indicates that ToxB requires at least 8 h in planta to induce maximum symptom development. In vitro assays demonstrate that apoplastic fluids extracted from toxin-sensitive and -insensitive wheat cultivars cannot degrade ToxB. Additionally, ToxB can be reisolated from apoplastic fluid after toxin infiltration. Furthermore, localization studies of fluorescently labeled ToxB indicate that the toxin remains in the apoplast in toxin-sensitive and -insensitive wheat cultivars. Our findings support the hypothesis that ToxB acts as an extracellular effector.

scholarly journals Expression of the ToxA and PtrPf2 genes of the phytopathogenic fungus Pyrenophora tritici-repentis at the beginning of the infection process

2019 ◽  
Author(s):  
Nina V. Mironenko ◽  
Alexandra S. Orina ◽  
Nadezhda M. Kovalenko
Keyword(s):  
Transcription Factor ◽  
Wheat Variety ◽  
Infection Process ◽  
Phytopathogenic Fungus ◽  
In Planta ◽  
Effector Gene ◽  
Pyrenophora Tritici Repentis ◽  
Wheat Leaves ◽  
Necrotrophic Effector

This study shows that the necrotrophic effector gene ToxA is differentially expressed in isolates of P. tritici-repentis fungus at different time periods after inoculation of the wheat variety Glenlea which has the gene Tsn1 controlling sensitivity to the necrosis inducing toxin Ptr ToxA. Two P. tritici-repentis isolates with different ability to cause necrosis on the leaves of Glenlea variety (nec + and nec-) and with different expression level of ToxA and gene of factor transcription PtrPf2 in vitro were used for analysis. Isolates of P. tritici-repentis are characterized by the differential expression of ToxA in planta. The expression of the ToxA gene in P. tritici-repentis ToxA+ isolates significantly increased when infected the wheat leaves compared to ToxA expression results obtained in vitro. The levels of ToxA expression in both isolates differed significantly after 24, 48 and 96 hours after inoculation, however, the dynamics of the trait change over time were similar. However, the highest ToxA expression in the virulent (nec+) isolate in contrast with the avirulent (nec-) isolate was observed at a point of 48 hours. Whereas the expression of regulating transcription factor PtrPf2 in planta differed imperceptibly from expression in vitro throughout the observation period. Obviously, the role of the fungal transcription factor in regulating the effector gene expression weakens in planta, and other mechanisms regulating the expression of pathogen genes at the biotrophic stage of the disease develop.

scholarly journals HC-Pro protein of sugar cane mosaic virus interacts specifically with maize ferredoxin-5 in vitro and in planta

2008 ◽  
Vol 89 (8) ◽  
pp. 2046-2054 ◽  
Author(s):  
Yu-Qin Cheng ◽  
Zhong-Mei Liu ◽  
Jian Xu ◽  
Tao Zhou ◽  
Meng Wang ◽  
...  
Keyword(s):  
Mosaic Virus ◽  
Sugar Cane ◽  
Transit Peptide ◽  
Viral Disease ◽  
Middle Part ◽  
Symptom Development ◽  
In Planta ◽  
Maize Plants ◽  
And Function

Symptom development of a plant viral disease is a result of molecular interactions between the virus and its host plant; thus, the elucidation of specific interactions is a prerequisite to reveal the mechanism of viral pathogenesis. Here, we show that the chloroplast precursor of ferredoxin-5 (Fd V) from maize (Zea mays) interacts with the multifunctional HC-Pro protein of sugar cane mosaic virus (SCMV) in yeast, Nicotiana benthamiana cells and maize protoplasts. Our results demonstrate that the transit peptide rather than the mature protein of Fd V precursor could interact with both N-terminal (residues 1–100) and C-terminal (residues 301–460) fragments, but not the middle part (residues 101–300), of HC-Pro. In addition, SCMV HC-Pro interacted only with Fd V, and not with the other two photosynthetic ferredoxin isoproteins (Fd I and Fd II) from maize plants. SCMV infection significantly downregulated the level of Fd V mRNA in maize plants; however, no obvious changes were observed in levels of Fd I and Fd II mRNA. These results suggest that SCMV HC-Pro interacts specifically with maize Fd V and that this interaction may disturb the post-translational import of Fd V into maize bundle-sheath cell chloroplasts, which could lead to the perturbation of chloroplast structure and function.

Chemical synthesis and characterization of a new quinazolinedione competitive antagonist for strigolactone receptors with an unexpected binding mode

2019 ◽  
Vol 476 (12) ◽  
pp. 1843-1856 ◽  
Author(s):  
Cyril Hamiaux ◽  
Lesley Larsen ◽  
Hui Wen Lee ◽  
Zhiwei Luo ◽  
Prachi Sharma ◽  
...  
Keyword(s):  
In Silico ◽  
Binding Mode ◽  
Crystal Structure Analysis ◽  
Tolfenamic Acid ◽  
In Vitro Assays ◽  
Inhibition Mechanism ◽  
In Planta ◽  
Competitive Antagonist ◽  
In Silico Docking

Abstract Strigolactones (SLs) are multifunctional plant hormones regulating essential physiological processes affecting growth and development. In vascular plants, SLs are recognized by α/β hydrolase-fold proteins from the D14/DAD2 (Dwarf14/Decreased Apical Dominance 2) family in the initial step of the signaling pathway. We have previously discovered that N-phenylanthranilic acid derivatives (e.g. tolfenamic acid) are potent antagonists of SL receptors, prompting us to design quinazolinone and quinazolinedione derivatives (QADs and QADDs, respectively) as second-generation antagonists. Initial in silico docking studies suggested that these compounds would bind to DAD2, the petunia SL receptor, with higher affinity than the first-generation compounds. However, only one of the QADs/QADDs tested in in vitro assays acted as a competitive antagonist of SL receptors, with reduced affinity and potency compared with its N-phenylanthranilic acid ‘parent’. X-ray crystal structure analysis revealed that the binding mode of the active QADD inside DAD2's cavity was not that predicted in silico, highlighting a novel inhibition mechanism for SL receptors. Despite a ∼10-fold difference in potency in vitro, the QADD and tolfenamic acid had comparable activity in planta, suggesting that the QADD compensates for lower potency with increased bioavailability. Altogether, our results establish this QADD as a novel lead compound towards the development of potent and bioavailable antagonists of SL receptors.

scholarly journals The In Vitro and In Planta Interspecies Interactions Among Rice-Pathogenic Burkholderia Species

Plant Disease ◽  
2021 ◽  
Vol 105 (1) ◽  
pp. 134-143
Author(s):  
Namgyu Kim ◽  
Mohamed Mannaa ◽  
Juyun Kim ◽  
Ji-Eun Ra ◽  
Sang-Min Kim ◽  
...  
Keyword(s):  
Inhibitory Activity ◽  
Fluorescent Protein ◽  
Antagonistic Activity ◽  
In Vitro Assays ◽  
Interspecies Interactions ◽  
In Planta ◽  
Burkholderia Glumae ◽  
Burkholderia Species ◽  
Green Fluorescent

Burkholderia glumae, B. plantarii, and B. gladioli are responsible for serious diseases in rice crops and co-occurrence among them has been reported. In this study, in vitro assays revealed antagonistic activity among these organisms, with B. gladioli demonstrating strong inhibition of B. glumae and B. plantarii. Strains of B. glumae and B. plantarii that express green fluorescent protein were constructed and used for cocultivation assays with B. gladioli, which confirmed the strong inhibitory activity of B. gladioli. Cell-free supernatants from each species were tested against cultures of counterpart species to evaluate the potential to inhibit bacterial growth. To investigate the inhibitory activity of B. gladioli on B. glumae and B. plantarii in rice, rice plant assays were performed and quantitative PCR (qPCR) assays were developed for in planta bacterial quantification. The results indicated that coinoculation with B. gladioli leads to significantly reduced disease severity and colonization of rice tissues compared with single inoculation with B. glumae or B. plantarii. This study demonstrates the interactions among three rice-pathogenic Burkholderia species and strong antagonistic activity of B. gladioli in vitro and in planta. The qPCR assays developed here could be applied for accurate quantification of these organisms from in planta samples in future studies.

scholarly journals Isolate Virulence and Cultivar Response in the Winter Wheat: Pyrenophora tritici-repentis (Tan Spot) Pathosystem in Oklahoma

2021 ◽  
Vol 37 (4) ◽  
pp. 339-346
Author(s):  
Kazi A. Kader ◽  
Robert M. Hunger ◽  
Mark E. Payton
Keyword(s):  
Cluster Analysis ◽  
Leaf Area ◽  
Tan Spot ◽  
Wheat Cultivars ◽  
Cultivar Resistance ◽  
Wheat Varieties ◽  
Pyrenophora Tritici Repentis ◽  
Greenhouse Study ◽  
No Till ◽  
Increased Susceptibility

Prevalence of tan spot of wheat caused by the fungus Pyrenophora tritici-repentis has become more prevalent in Oklahoma as no-till cultivation in wheat has increased. Hence, developing wheat varieties resistant to tan spot has been emphasized, and selecting pathogen isolates to screen for resistance to this disease is critical. Twelve isolates of P. tritici-repentis were used to inoculate 11 wheat cultivars in a greenhouse study in splitplot experiments. Virulence of isolates and cultivar resistance were measured in percent leaf area infection for all possible isolate x cultivar interactions. Isolates differed significantly (P < 0.01) in virulence on wheat cultivars, and cultivars differed significantly in disease reaction to isolates. Increased virulence of isolates detected increased variability in cultivar response (percent leaf area infection) (r = 0.56, P < 0.05) while increased susceptibility in cultivars detected increased variance in virulence of the isolates (r = 0.76, P < 0.01). A significant isolate × cultivar interaction indicated specificity between isolates and cultivars, however, cluster analysis indicated low to moderate physiological specialization. Similarity in wheat cultivars in response to pathogen isolates also was determined by cluster analysis. The use of diverse isolates of the fungus would facilitate evaluation of resistance in wheat cultivars to tan spot.

scholarly journals Emergence of Tan Spot Disease Caused by Toxigenic Pyrenophora tritici-repentis in Australia Is Not Associated with Increased Deployment of Toxin-Sensitive Cultivars

2008 ◽  
Vol 98 (5) ◽  
pp. 488-491 ◽  
Author(s):  
R. P. Oliver ◽  
M. Lord ◽  
K. Rybak ◽  
J. D. Faris ◽  
P. S. Solomon
Keyword(s):  
The United States ◽  
Tan Spot ◽  
Wheat Cultivars ◽  
Tillage Practices ◽  
Pyrenophora Tritici Repentis ◽  
South Wales ◽  
Glume Blotch ◽  
Wheat Gene ◽  
Serious Disease ◽  
Wheat Lines

The wheat disease tan (or yellow leaf) spot, caused by Pyrenophora tritici-repentis, was first described in the period 1934 to 1941 in Canada, India, and the United States. It was first noted in Australia in 1953 and only became a serious disease in the 1970s. The emergence of this disease has recently been linked to the acquisition by P. tritici-repentis of the ToxA gene from the wheat leaf and glume blotch pathogen, Stagonospora nodorum. ToxA encodes a host-specific toxin that interacts with the product of the wheat gene Tsn1. Interaction of ToxA with the dominant allele of Tsn1 causes host necrosis. P. tritici-repentis races lacking ToxA give minor indistinct lesions on wheat lines, whereas wheat lines expressing the recessive tsn1 are significantly less susceptible to the disease. Although the emergence and spread of tan spot had been attributed to the adoption of minimum tillage practices, we wished to test the alternative idea that the planting of Tsn1 wheat lines may have contributed to the establishment of the pathogen in Australia. To do this, wheat cultivars released in Australia from 1911 to 1986 were tested for their sensitivity to ToxA. Prior to 1941, 16% of wheat cultivars were ToxA-insensitive and hence, all other factors being equal, would be more resistant to the disease. Surprisingly, only one of the cultivars released since 1940 was ToxA insensitive, and the area planted to ToxA-insensitive cultivars varied from 0 to a maximum of only 14% in New South Wales. Thus, the majority of the cultivars were ToxA-sensitive both before and during the period of emergence and spread of the disease. We therefore conclude that the spread of P. tritici-repentis in Australia cannot be causally linked to the deployment of ToxA-sensitive cultivars.

scholarly journals In Vitro Quantitative Resistance Components in Wheat Plants to Fusarium Head Blight

2019 ◽  
Vol 13 (1) ◽  
pp. 9-18 ◽  
Author(s):  
Nachaat Sakr
Keyword(s):  
Quantitative Resistance ◽  
Petri Dish ◽  
Lesion Length ◽  
Type Ii ◽  
Wheat Cultivars ◽  
In Planta ◽  
Head Blight ◽  
Detached Leaf ◽  
Fhb Resistance

Background: In vitro tools have proved to be very useful in identifying quantitative resistance in wheat to Fusarium Head Blight (FHB) infection. However, there is a need to understand how the different in vitro and in planta tests correlate to describe the level of wheat resistance to FHB infection. Objective and Methods: We evaluated the correlation between in vitro symptom assessment using nine quantitative resistance criteria and in planta disease severity for Type II resistance assessment using a set of 16 FHB isolates across two widely grown Syrian wheat cultivars: Cham1 (durum) and Cham6 (bread). Results: Cultivar differences after inoculation with fungal isolates in seedlings and adult plants relative to the controls were detected. There were significant differences in the resistance of two wheat cultivars as measured by adult FHB resistance, Latent Period (LP) of detached leaf inoculation and standardized Area Under Disease Progress Curve (AUDPCstandard) of modified Petri-dish inoculation. Correlation coefficients between FHB severity and the two in vitro components LP and AUDPCstandard were significant (r=0.545 with p<0.05, and r=0.659 with p<0.01, respectively). No significant differences in the resistance of Cham6 and Cham1 were indicated for the other seven in vitro components: incubation period and lesion length of detached leaf inoculation, germination rate reduction and coleoptile length reduction of modified Petri-dish inoculation and lesion length of clip-dipping inoculation and percentage of infected seedlings of foliar-spraying and pin-point inoculations. Results from these seven components were not correlated with adult FHB resistance. Longer latent period and less AUDPCstandard were related to greater FHB disease-type II resistance. Conclusion: LP and AUDPCstandard are indicators of mechanisms of resistance occurring in the whole plant during FHB infection. Therefore, the idea of using in vitro components is based on their predictive ability of in planta adult FHB resistance.

scholarly journals A Polygalacturonase-Inhibiting Protein from Grapevine Reduces the Symptoms of the Endopolygalacturonase BcPG2 from Botrytis cinerea in Nicotiana benthamiana Leaves Without Any Evidence for In Vitro Interaction

2007 ◽  
Vol 20 (4) ◽  
pp. 392-402 ◽  
Author(s):  
Dirk A. Joubert ◽  
Ilona Kars ◽  
Lia Wagemakers ◽  
Carl Bergmann ◽  
Gabré Kemp ◽  
...  
Keyword(s):  
Botrytis Cinerea ◽  
Nicotiana Benthamiana ◽  
Substantial Reduction ◽  
In Vitro Assays ◽  
Physical Interaction ◽  
In Planta ◽  
Polygalacturonase Inhibiting Protein ◽  
Inhibiting Protein

Six endopolygalacturonases from Botrytis cinerea (BcPG1 to BcPG6) as well as mutated forms of BcPG1 and BcPG2 were expressed transiently in leaves of Nicotiana benthamiana using agroinfiltration. Expression of BcPG1, BcPG2, BcPG4, BcPG5, and mutant BcPG1-D203A caused symptoms, whereas BcPG3, BcPG6, and mutant BcPG2-D192A caused no symptoms. Expression of BcPG2 caused the most severe symptoms, including wilting and necrosis. BcPG2 previously has been shown to be essential for B. cinerea virulence. The in vivo effect of this enzyme and the inhibition by a polygalacturonase-inhibiting protein (PGIP) was examined by coexpressing Bcpg2 and the Vvpgip1 gene from Vitis vinifera in N. benthamiana. Coinfiltration resulted in a substantial reduction of the symptoms inflicted by the activity of BcPG2 in planta, as evidenced by quantifying the variable chlorophyll fluorescence yield. In vitro, however, no interaction between pure VvPGIP1 and pure BcPG2 was detected. Specifically, VvPGIP1 neither inhibited BcPG2 activity nor altered the degradation profile of polygalacturonic acid by BcPG2. Furthermore, using surface plasmon resonance technology, no physical interaction between VvPGIP1 and BcPG2 was detected in vitro. The data suggest that the in planta environment provided a context to support the interaction between BcPG2 and VvPGIP1, leading to a reduction in symptom development, whereas neither of the in vitro assays detected any interaction between these proteins.

scholarly journals Identification and Characterization of Novel Isolates of Pyrenophora tritici-repentis from Arkansas

Plant Disease ◽  
2010 ◽  
Vol 94 (2) ◽  
pp. 229-235 ◽  
Author(s):  
Shaukat Ali ◽  
Suraj Gurung ◽  
Tika B. Adhikari
Keyword(s):  
The United States ◽  
Tan Spot ◽  
Wheat Cultivars ◽  
Pyrenophora Tritici Repentis ◽  
Winter Wheat Cultivars ◽  
Race 1 ◽  
Preliminary Study ◽  
Polymerase Chain ◽  
Identification And Characterization

Tan spot, caused by Pyrenophora tritici-repentis, is an important foliar disease of wheat (Triticum aestivum) worldwide. In a preliminary study, P. tritici-repentis isolates from Arkansas were shown to vary in virulence relative to isolates from other regions of the United States. Therefore, the aim of the current study was to characterize both pathogenic and molecular variations in P. tritici-repentis isolates from Arkansas. The virulence of 93 isolates of P. tritici-repentis was evaluated by inoculating five differential wheat cultivars/lines. Based on virulence phenotypes, 63 isolates were classified as race 1, and 30 isolates were assigned to race 3. A subset of 42 isolates was selected for molecular characterization with the presence or absence of the ToxA and ToxB genes. The results showed that 36 isolates out of 42 tested by polymerase chain reaction (PCR) and Southern analysis lacked the ToxA and ToxB genes. Six isolates harboring the ToxA and ToxB genes induced necrosis and chlorosis on Glenlea and 6B365, respectively. Thirteen ToxA gene-deficient isolates also caused necrosis and chlorosis on Glenlea and 6B365, respectively; however, they did not fit current race classification. In contrast, the remaining 23 ToxA gene-deficient isolates did not cause necrosis, but induced chlorosis on 6B365, showing a disease profile for race 3. When the virulence of AR LonB2 (an isolate with unclassified race) was compared with known races 1, 3, and 5 of P. tritici-repentis on 20 winter wheat cultivars from Arkansas, the virulence phenotypes differed substantially. Taken together, the ToxA and ToxB gene-deficient isolates of P. tritici-repentis that induce necrosis and/or chlorosis may produce a novel toxin(s) on wheat.

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