scholarly journals Identification of a virulence tal gene in the cotton pathogen, Xanthomonas citri pv. malvacearum strain Xss-V2-18

2020 ◽  
Author(s):  
Fazal Haq ◽  
Shiwang Xie ◽  
Kunxuan Huang ◽  
Syed Mashab Ali Shah ◽  
Wenxiu Ma ◽  
...  
Keyword(s):  
Virulent Strain ◽  
Evolutionary Relationship ◽  
The United States ◽  
In Planta ◽  
Dna Encoding ◽  
Transcription Activator ◽  
Xanthomonas Citri ◽  
Tn5 Transposon ◽  
Suicide Vector ◽  
In Trans

Abstract Background: Bacterial blight of cotton (BBC), which is caused by the bacterium Xanthomonas citri pv. malvacearum (Xcm), is a destructive disease in cotton. Transcription activator-like effectors (TALEs), encoded by tal-genes, play critical roles in the pathogenesis of xanthomonads. Characterized strains of cotton pathogenic Xcm harbor 8-12 different tal genes and only one of them is functionally decoded. Further identification of novel tal genes in Xcm strains with virulence contributions are prerequisite to decipher the Xcm-cotton interactions. Results: In this study, we identified six tal genes in Xss-V2-18, a highly-virulent strain of Xcm from China, and assessed their role in BBC. RFLP-based Southern hybridization assays indicated that Xss-V2-18 harbors the six tal genes on a plasmid. The plasmid-encoded tal genes were isolated by cloning BamHI fragments and screening clones by colony hybridization. The tal genes were sequenced by inserting a Tn5 transposon in the DNA encoding the central repeat region (CRR) of each tal gene. Xcm TALome evolutionary relationship based on TALEs CRR revealed relatedness of Xss-V2-18 to MSCT1 and MS14003 from the United States. However, Tal2 of Xss-V2-18 differs at two repeat variable diresidues (RVDs) from Tal6 and Tal26 in MSCT1 and MS14003, respectively, inferred functional dissimilarity. The suicide vector pKMS1 was then used to construct tal deletion mutants in Xcm Xss-V2-18. The mutants were evaluated for pathogenicity in cotton based on symptomology and growth in planta. Four mutants showed attenuated virulence and all contained mutations in tal2. One tal2 mutant designated M2 was further investigated in complementation assays. When tal2 was introduced into Xcm M2 and expressed in trans, the mutant was complemented for both symptoms and growth in planta, thus indicating that tal2 functions as a virulence factor in Xcm Xss-V2-18. Conclusions: Overall, the results demonstrated that Tal2 is a major pathogenicity factor in Xcm strain Xss-V2-18 that contributes significantly in BBC. This study provides a foundation for future efforts aimed at identifying susceptibility genes in cotton that are targeted by Tal2.

scholarly journals Identification of virulence tal gene in the cotton pathogen, Xanthomonas citri pv. malvacearum strain Xss-V2-18

2020 ◽  
Author(s):  
Fazal Haq ◽  
Syed Mashab Ali Shah ◽  
Shiwang Xie ◽  
Kunxuan Huang ◽  
Wenxiu Ma ◽  
...  
Keyword(s):  
Virulent Strain ◽  
Evolutionary Relationship ◽  
The United States ◽  
In Planta ◽  
Dna Encoding ◽  
Transcription Activator ◽  
Xanthomonas Citri ◽  
Suicide Vector ◽  
In Trans ◽  
Highly Virulent

Abstract Background Bacterial blight of cotton (BBC), which is incited by Xanthomonas citri pv. malvacearum ( Xcm ), is a destructive disease in cotton. Transcription activator-like effectors (TALEs), encoded by tal -genes, play critical roles in the pathogenesis of xanthomonads. Characterized strains of cotton pathogenic Xcm harbor 6-13 different tal genes and only one of them is functionally decoded. Further identification of novel tal genes in Xcm strains with virulence contributions are prerequisite to decipher the Xcm -cotton interactionsResults In this study, we identified six tal genes in Xss-V 2 -18, a highly-virulent strain of Xcm from China, and assessed their role in BBC. RFLP-based Southern hybridization assays indicated that Xss-V 2 -18 harbors the six tal genes on a plasmid. The plasmid-encoded tal genes were isolated by cloning Bam HI fragments and screening clones by colony hybridization. The tal genes were sequenced by inserting a Tn 5 transposon in the DNA encoding the central repeat region (CRR) of each tal gene. Xcm TALome evolutionary relationship based on TALEs CRR revealed relatedness of Xss-V 2 -18 to MSCT1 and MS14003 from the United States. However, Tal2 of Xss-V 2 -18 differs at two repeat variable diresidues (RVDs) from Tal6 and Tal26 in MSCT1 and MS14003, respectively, inferred functional dissimilarity. The suicide vector pKMS1 was then used to construct tal deletion mutants in Xcm Xss-V 2 -18. The mutants were evaluated for pathogenicity in cotton based on symptomology and growth in planta . Four mutants showed attenuated virulence and all contained mutations in tal2 . One tal2 mutant designated M2 was further investigated in complementation assays. When tal2 was introduced into Xcm M2 and expressed in trans , the mutant was complemented for both symptoms and growth in planta , thus indicating that tal2 functions as a virulence factor in Xcm Xss-V 2 -18.Conclusions Overall, the results demonstrated that Tal2 is a major pathogenicity factor in Xcm strain Xss-V 2 -18 that contributes significantly in BBC. This study provides a foundation for future efforts aimed at identifying susceptibility genes in cotton that are targeted by Tal2.

scholarly journals Tal2 is a major virulence factor in the cotton pathogen, Xanthomonas citri pv. malvacearum Xss-V2-18

2019 ◽  
Author(s):  
Fazal Haq ◽  
Syed Mashab Ali Shah ◽  
Shiwang Xie ◽  
Huangkun Xuan ◽  
Wenxiu Ma ◽  
...  
Keyword(s):  
Virulence Factor ◽  
Virulent Strain ◽  
The United States ◽  
In Planta ◽  
Dna Encoding ◽  
Transcription Activator ◽  
Xanthomonas Citri ◽  
Tal Effectors ◽  
Tn5 Transposon ◽  
Suicide Vector

Abstract Background Bacterial blight of cotton (BBC), which is incited by Xanthomonas citri pv. malvacearum (Xcm), is a destructive disease in cotton. Transcription activator-like (tal) effectors (TALEs) play critical roles in the pathogenesis of xanthomonads; however, TALEs have not been well-investigated in the Xcm – cotton interaction.Results In this study, we identified six tal genes in Xcm Xss-V2-18, a highly-virulent strain from China, and assessed their roles in BBC. RFLP-based Southern hybridization assays indicated that Xss-V2-18 harbors the six tal genes on a plasmid. The plasmid-encoded tal genes were isolated by cloning BamHI fragments and screening clones by colony hybridization. The tal genes were sequenced by inserting a Tn5 transposon in the DNA encoding the central repeat region of each tal gene. Phylogenetically the TALEs in Xss-V2-18 show close similarity to the TALEs in Xcm strains MSCT1 and MS14003 from the United States. Tal2 in Xss-V2-18 differs from Tal6 and Tal26 in MSCT1 and MS14003, respectively, at two repeat variable diresidues (RVDs) indicates that they are functionally different. The suicide vector pKMS1 was then used to construct tal deletion mutants in Xcm Xss-V2-18. The mutants were evaluated for pathogenicity in cotton based on symptomology and growth in planta. Four mutants showed attenuated virulence and all contained mutations in tal2. One tal2 mutant designated M2 was further investigated in complementation assays. When tal2 was introduced into Xcm M2 and expressed in trans, the mutant was complemented for both symptoms and growth in planta, thus indicating that tal2 functions as a virulence factor in Xcm Xss-V2-18.Conclusions Overall, the results demonstrated that Tal2 is a major pathogenicity factor in Xcm Xss-V2-18 that contributes significantly in BBC. This study provides a foundation for future efforts aimed at identifying susceptibility genes in cotton that are targeted by Tal2.

scholarly journals Pan-Genome Analysis of Effectors in Korean Strains of the Soybean Pathogen Xanthomonas citri pv. glycines

2021 ◽  
Vol 9 (10) ◽  
pp. 2065
Author(s):  
In-Jeong Kang ◽  
Kyung Seok Kim ◽  
Gwyn Beattie ◽  
Jung-Wook Yang ◽  
Kee Hoon Sohn ◽  
...  
Keyword(s):  
Genome Analysis ◽  
Type Iii Secretion ◽  
The United States ◽  
Comparative Genome Analysis ◽  
Transcription Activator ◽  
Xanthomonas Citri ◽  
Carbohydrate Active Enzymes ◽  
Soybean Cultivars ◽  
Binding Domains ◽  
Effector Binding

Xanthomonas citri pv. glycines is a major pathogen of soybean in Korea. Here, we analyzed pathogenicity genes based on a comparative genome analysis of five Korean strains and one strain from the United States, 8ra. Whereas all six strains had nearly identical profiles of carbohydrate-active enzymes, they varied in diversity and number of candidate type III secretion system effector (T3SE) genes. The five Korean strains were similar in their effectors, but differed from the 8ra strain. Across the six strains, transcription activator-like effectors (TALEs) showed diverse repeat sizes and at least six forms of the repeat variable di-residue (RVD) sequences, with differences not correlated with the origin of the strains. However, a phylogenetic tree based on the alignment of RVD sequences showed two distinct clusters with 17.5 repeats, suggesting that two distinct 17.5 RVD clusters have evolved, potentially to adapt Xcg to growth on distinct soybean cultivars. The predicted effector binding elements of the TALEs fell into six groups and were strongly overlapping in sequence, suggesting evolving target specificity of the binding domains in soybean cultivars. Our findings reveal the variability and adaptability of T3SEs in the Xcg strains and enhance our understanding of Xcg pathogenicity in soybean.

scholarly journals Genomics-enabled analysis of the emergent disease cotton bacterial blight

2017 ◽  
Author(s):  
Anne Z. Phillips ◽  
Jeffrey C. Berry ◽  
Mark C. Wilson ◽  
Anupama Vijayaraghavan ◽  
Jillian Burke ◽  
...  
Keyword(s):  
Rna Sequencing ◽  
Resistance Genes ◽  
Bacterial Blight ◽  
Durable Resistance ◽  
Gene List ◽  
Susceptibility Gene ◽  
The United States ◽  
Transcription Activator ◽  
Xanthomonas Citri ◽  
Putative Gene

AbstractCotton bacterial blight (CBB), an important disease of (Gossypium hirsutum) in the early 20th century, had been controlled by resistant germplasm for over half a century. Recently, CBB re-emerged as an agronomic problem in the United States. Here, we report analysis of cotton variety planting statistics that indicate a steady increase in the percentage of susceptible cotton varieties grown each year since 2009. Phylogenetic analysis revealed that strains from the current outbreak cluster with race 18 Xanthomonas citri pv. malvacearum (Xcm) strains.Illumina based draft genomes were generated for thirteen Xcm isolates and analyzed along with 4 previously published Xcm genomes. These genomes encode 24 conserved and nine variable type three effectors. Strains in the race 18 clade contain 3 to 5 more effectors than other Xcm strains. SMRT sequencing of two geographically and temporally diverse strains of Xcm yielded circular chromosomes and accompanying plasmids. These genomes encode eight and thirteen distinct transcription activator-like effector genes. RNA-sequencing revealed 52 genes induced within two cotton cultivars by both tested Xcm strains. This gene list includes a homeologous pair of genes, with homology to the known susceptibility gene, MLO. In contrast, the two strains of Xcm induce different clade III SWEET sugar transporters. Subsequent genome wide analysis revealed patterns in the overall expression of homeologous gene pairs in cotton after inoculation by Xcm. These data reveal host-pathogen specificity at the genetic level and strategies for future development of resistant cultivars.Author SummaryCotton bacterial blight (CBB), caused by Xanthomonas citri pv. malvacearum (Xcm), significantly limited cotton yields in the early 20th century but has been controlled by classical resistance genes for more than 50 years. In 2011, the pathogen re-emerged with a vengeance. In this study, we compare diverse pathogen isolates and cotton varieties to further understand the virulence mechanisms employed by Xcm and to identify promising resistance strategies. We generate fully contiguous genome assemblies for two diverse Xcm strains and identify pathogen proteins used to modulate host transcription and promote susceptibility. RNA-Sequencing of infected cotton reveals novel putative gene targets for the development of durable Xcm resistance. Together, the data presented reveal contributing factors for CBB re-emergence in the U.S. and highlight several promising routes towards the development of durable resistance including classical resistance genes and potential manipulation of susceptibility targets.

scholarly journals Transnationalism as a Decolonizing Strategy? ‘Trans-Indigenism’ and Native American Food Sovereignty

2018 ◽  
Vol 53 (s1) ◽  
pp. 413-423
Author(s):  
Zuzanna Kruk-Buchowska
Keyword(s):  
United States ◽  
Native American ◽  
Knowledge Production ◽  
Food Sovereignty ◽  
Indigenous Communities ◽  
The United States ◽  
Scientific Paradigms ◽  
Nation States ◽  
In Trans ◽  
Indigenous Methods

Abstract The aim of this paper is to analyze how Indigenous communities in the United States have been engaging in trans-Indigenous cooperation in their struggle for food sovereignty. I will look at inter-tribal conferences regarding food sovereignty and farming, and specifically at the discourse of the Indigenous Farming Conference held in Maplelag at the White Earth Reservation in northern Minnesota. I will show how it: (1) creates a space for Indigenous knowledge production and validation, using Indigenous methods (e.g., storytelling), without the need to adhere to Western scientific paradigms; (2) recovers pre-colonial maps and routes distorted by the formation of nation states; and (3) fosters novel sites for trans-indigenous cooperation and approaches to law, helping create a common front in the fight with neoliberal agribusiness and government. In my analysis, I will use Chadwick Allen’s (2014) concept of ‘trans-indigenism’ to demonstrate how decolonizing strategies are used by the Native American food sovereignty movement to achieve their goals.

scholarly journals A Set of Conventional and Multiplex Real-Time PCR Assays for Direct Detection of Elsinoë fawcettii, E. australis, and Pseudocercospora angolensis in Citrus Fruits

Plant Disease ◽  
2019 ◽  
Vol 103 (2) ◽  
pp. 345-356 ◽  
Author(s):  
Yosra Ahmed ◽  
Jacqueline Hubert ◽  
Céline Fourrier-Jeandel ◽  
Megan M. Dewdney ◽  
Jaime Aguayo ◽  
...  
Keyword(s):  
Real Time ◽  
Real Time Pcr ◽  
Culture Media ◽  
Direct Detection ◽  
Elongation Factor ◽  
Single Copy ◽  
The United States ◽  
Performance Criteria ◽  
In Planta ◽  
Conventional Pcr

Elsinoë fawcettii, E. australis, and Pseudocercospora angolensis are causal agents of citrus scab and spot diseases. The three pathogens are listed as quarantine pests in many countries and are subject to phytosanitary measures to prevent their entry. Diagnosis of these diseases based on visual symptoms is problematic, as they could be confused with other citrus diseases. Isolation of E. fawcettii, E. australis, and P. angolensis from infected tissues is challenging because they grow slowly on culture media. This study developed rapid and specific detection tools for the in planta detection of these pathogens, using either conventional PCR or one-tube multiplex real-time PCR. Primers and hybridization probes were designed to target the single-copy protein-coding gene MS204 for E. fawcettii and E. australis and the translation elongation factor (Tef-1α) gene for P. angolensis. The specificity of the assays was evaluated by testing against DNA extracted from a large number of isolates (102) collected from different citrus-growing areas in the world and from other hosts. The newly described species E. citricola was not included in the specificity test due to its unavailability from the CBS collection. The detection limits of conventional PCR for the three pathogens were 100, 100, and 10 pg μl−1 gDNA per reaction for E. fawcettii, E. australis, and P. angolensis, respectively. The quadruplex qPCR was fully validated assessing the following performance criteria: sensitivity, specificity, repeatability, reproducibility, and robustness. The quadruplex real-time PCR proved to be highly sensitive, detecting as low as 243, 241, and 242 plasmidic copies (pc) μl−1 of E. fawcettii, E. australis, and P. angolensis, respectively. Sensitivity and specificity of this quadruplex assay were further confirmed using 176 naturally infected citrus samples collected from Ethiopia, Cameroon, the United States, and Australia. The quadruplex assay developed in this study is robust, cost-effective, and capable of high-throughput detection of the three targets directly from citrus samples. This new detection tool will substantially reduce the turnaround time for reliable species identification and allow rapid response and appropriate action.

scholarly journals Identification of Loci of Pseudomonas syringae pv. actinidiae Involved in Lipolytic Activity and Their Role in Colonization of Kiwifruit Leaves

2017 ◽  
Vol 107 (6) ◽  
pp. 645-653 ◽  
Author(s):  
Hitendra Kumar Patel ◽  
Patrizia Ferrante ◽  
Meng Xianfa ◽  
Sree Gowrinadh Javvadi ◽  
Sujatha Subramoni ◽  
...  
Keyword(s):  
Pseudomonas Syringae ◽  
Plant Pathogens ◽  
Lipid A ◽  
Lipolytic Activity ◽  
Genetic Screen ◽  
Economic Losses ◽  
In Planta ◽  
Tn5 Transposon ◽  
Tn5 Mutants ◽  
Transposon Mutants

Bacterial canker disease caused by Pseudomonas syringae pv. actinidiae, an emerging pathogen of kiwifruit plants, has recently brought about major economic losses worldwide. Genetic studies on virulence functions of P. syringae pv. actinidiae have not yet been reported and there is little experimental data regarding bacterial genes involved in pathogenesis. In this study, we performed a genetic screen in order to identify transposon mutants altered in the lipolytic activity because it is known that mechanisms of regulation, production, and secretion of enzymes often play crucial roles in virulence of plant pathogens. We aimed to identify the set of secretion and global regulatory loci that control lipolytic activity and also play important roles in in planta fitness. Our screen for altered lipolytic activity phenotype identified a total of 58 Tn5 transposon mutants. Mapping all these Tn5 mutants revealed that the transposons were inserted in genes that play roles in cell division, chemotaxis, metabolism, movement, recombination, regulation, signal transduction, and transport as well as a few unknown functions. Several of these identified P. syringae pv. actinidiae Tn5 mutants, notably the functions affected in phosphomannomutase AlgC, lipid A biosynthesis acyltransferase, glutamate–cysteine ligase, and the type IV pilus protein PilI, were also found affected in in planta survival and/or growth in kiwifruit plants. The results of the genetic screen and identification of novel loci involved in in planta fitness of P. syringae pv. actinidiae are presented and discussed.

scholarly journals Potential of a Small Molecule Carvacrol in Management of Vegetable Diseases

Molecules ◽  
2019 ◽  
Vol 24 (10) ◽  
pp. 1932 ◽  
Author(s):  
Qingchun Liu ◽  
Kang Qiao ◽  
Shouan Zhang
Keyword(s):  
Small Molecule ◽  
Plant Pathogens ◽  
The United States ◽  
South Florida ◽  
Human Consumption ◽  
Vegetable Crops ◽  
In Planta ◽  
Xanthomonas Perforans ◽  
Promising Tool ◽  
The Usa

Carvacrol, a plant-derived volatile small molecule, is effective against various agents that can cause damage to humans, the food processing industry, and plants, and is considered a safe substance for human consumption. In this short communication, previous studies on the effectiveness of carvacrol against various agents, particularly plant pathogens and their associated mechanisms are described. In our study, carvacrol was found to be effective on media against several soilborne pathogens and in planta against three foliar pathogens (Xanthomonas perforans, Alternaria tomatophila, and Podosphaeraxanthii) of important vegetable crops in south Florida of the United States. Current research findings indicated that the effectiveness of carvacrol against various plant pathogens tested was associated with its direct bactericidal/fungicidal effect, which was affected greatly by its volatility. Development of new formulations to overcome the volatility and to prolong the effectiveness of carvacrol was also presented. Our studies on carvacrol suggested that, with advanced development of new formulations, carvacrol could be used as a promising tool in the integrated pest management for bacterial, fungal, and viral pathogens of important vegetable crops in Florida, the USA, and the world.

Trans-Polar Aviation and Jurisdiction over Arctic Airspace

1943 ◽  
Vol 37 (6) ◽  
pp. 999-1013 ◽  
Author(s):  
Elmer Plischke
Keyword(s):  
Arctic Basin ◽  
The United States ◽  
The Arctic ◽  
Periodical Literature ◽  
World War ◽  
The North ◽  
The First World War ◽  
In Trans ◽  
First World ◽  
Present World

Current press articles and periodical literature, both in the United States and abroad, are manifesting a developing interest in trans-polar aviation and Arctic aërial jurisdiction. Although this interest in Arctic airspace appears to be conceived in the exigencies of the present world conflict, belief in the practicability of air routes traversing the Arctic Basin and joining the great centers of civilization of the two hemispheres was expressed as long ago as shortly after the First World War. Perhaps most vocal of the exponents is the polar explorer and publicist Vilhjalmur Stefansson, who began to stress the positional significance of the Arctic almost twenty years ago.Meanwhile the feasibility of polar aviation was demonstrated in actual practice. Following a series of experimental flights by dirigible and plane—and once the urge to attain the North Pole via the air materialized in the successful flights of Richard E. Byrd, Roald Amundsen-Lincoln Ellsworth, and Umberto Nobile in 1926 and 1928—polar flying concentrated largely upon the spanning of the Atlantic and Pacific aërial highways between the two hemispheres.

scholarly journals Tal2c Activates the Expression of OsF3H04g to Promote Infection as a Redundant TALE of Tal2b in Xanthomonas oryzae pv. oryzicola

2021 ◽  
Vol 22 (24) ◽  
pp. 13628
Author(s):  
Tao Wu ◽  
Haimiao Zhang ◽  
Yunya Bi ◽  
Yue Yu ◽  
Haifeng Liu ◽  
...  
Keyword(s):  
Virulent Strain ◽  
Xanthomonas Oryzae ◽  
Transcription Activator ◽  
Altered Expression ◽  
Overexpression Line ◽  
Dioxygenase Gene ◽  
Highly Virulent ◽  
Effector Binding ◽  
Host Genes ◽  
Increased Susceptibility

Xanthomonas oryzae delivers transcription activator-like effectors (TALEs) into plant cells to facilitate infection. Following economic principles, the redundant TALEs are rarely identified in Xanthomonas. Previously, we identified the Tal2b, which activates the expression of the rice 2-oxoglutarate-dependent dioxygenase gene OsF3H03g to promote infection in the highly virulent strain of X. oryzae pv. oryzicola HGA4. Here, we reveal that another clustered TALE, Tal2c, also functioned as a virulence factor to target rice OsF3H04g, a homologue of OsF3H03g. Transferring Tal2c into RS105 induced expression of OsF3H04g to coincide with increased susceptibility in rice. Overexpressing OsF3H04g caused higher susceptibility and less salicylic acid (SA) production compared to wild-type plants. Moreover, CRISPR–Cas9 system-mediated editing of the effector-binding element in the promoters of OsF3H03g or OsF3H04g was found to specifically enhance resistance to Tal2b- or Tal2c-transferring strains, but had no effect on resistance to either RS105 or HGA4. Furthermore, transcriptome analysis revealed that several reported SA-related and defense-related genes commonly altered expression in OsF3H04g overexpression line compared with those identified in OsF3H03g overexpression line. Overall, our results reveal a functional redundancy mechanism of pathogenic virulence in Xoc in which tandem Tal2b and Tal2c specifically target homologues of host genes to interfere with rice immunity by reducing SA.

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