scholarly journals Characterisation of the pathogenicity of strains of Pseudomonas syringae towards cherry and plum

2017 ◽  
Author(s):  
M.T. Hulin ◽  
J.W. Mansfield ◽  
P. Brain ◽  
X. Xiangming ◽  
R.W. Jackson ◽  
...  
Keyword(s):  
Pseudomonas Syringae ◽  
Host Resistance ◽  
Resistance Mechanisms ◽  
Genetic Dissection ◽  
Depth Study ◽  
Detached Leaves ◽  
Race 1 ◽  
Pathogenicity Tests ◽  
Race 2 ◽  
Cultivar Susceptibility

AbstractBacterial canker is a major disease of cherry and other stone fruits caused by several pathovars of Pseudomonas syringae. These are P.s pv. morsprunorum race 1 (Psm R1), P.s pv. morsprunorum race 2 (Psm R2) and P.s pv. syringae (Pss). Psm R1 and R2 were originally designated as races of the same pathovar, however phylogenetic analysis has revealed them to be distantly related. This study characterised the pathogenicity of P. syringae on cherry and plum, in the field and the laboratory. The field experiment identified variation in host cultivar susceptibility to the different pathogen clades. The cherry cultivar Merton Glory exhibited a broad resistance to all clades, whilst cultivar Van showed race-specific resistance. Psm R1 may be divided into a race structure with some strains pathogenic to both cherry and plum and others only pathogenic to plum. The results of laboratory-based pathogenicity tests were compared to results obtained on whole-trees. Only cut shoot inoculations were found to be sensitive enough to detect cultivar variation in susceptibility. Measuring population growth of bacteria in detached leaves reliably discriminated pathogens from non-pathogens. In addition, symptom appearance discriminated Psm races from non-pathogens which triggered a rapid hypersensitive response (HR). The pathogen Pss rapidly induced disease lesions and therefore may exhibit a more necrotrophic lifestyle than hemi-biotrophic Psm races. This in-depth study of pathogenic interactions, identification of host resistance and optimisation of laboratory assays, will provide a framework for future genetic dissection of virulence and host resistance mechanisms.

Variation in pathogenicity and virulence of Phytophthora clandestina on four cultivars of subterranean clover

1995 ◽  
Vol 35 (6) ◽  
pp. 717 ◽  
Author(s):  
A Purwantara ◽  
SP Flett ◽  
PJ Keane
Keyword(s):  
Growth Rate ◽  
Agar Medium ◽  
Sandy Loam ◽  
Severe Disease ◽  
Subterranean Clover ◽  
Race 1 ◽  
Pathogenicity Tests ◽  
Loam Soil ◽  
Race 2 ◽  
Cultivar Specificity

The pathogenicity of 6 isolates of Phytophthora clandestina on seedlings of 4 cultivars of subterranean clover was studied. There was a highly significant isolate x cultivar interaction in pathogenicity tests on axenic seedlings and seedlings grown in pasteurised potting mix or untreated sandy loam soil, indicating the existence of race-cultivar specificity. The isolates showed differences in virulence against the cultivars. Three isolates (race 0) caused severe disease only on Woogenellup; 2 isolates (race 1) caused severe disease on Larisa, Trikkala, and Woogenellup, but not on Meteora; one isolate (race 2) caused severe disease on Meteora and Woogenellup, but not on Larisa and Trikkala. As well as differing in virulence (the ability of a race to attack a range of cultivars), the races also differed in their aggressiveness on Woogenellup, with race 2 being the most, and race 0 the least, pathogenic. The isolates varied in their growth rate on agar medium, but this was not related to virulence or aggressiveness.

scholarly journals Genetic Diversity of Fusarium oxysporum f. sp. dianthi in Southern Spain

2014 ◽  
Vol 2014 ◽  
pp. 1-14 ◽  
Author(s):  
Raúl Castaño ◽  
Barbara Scherm ◽  
Manuel Avilés
Keyword(s):  
Fusarium Oxysporum ◽  
Phylogenetic Analyses ◽  
Gene Sequencing ◽  
Southern Spain ◽  
Specific Pcr ◽  
Rapd Pcr ◽  
Race 1 ◽  
Pathogenicity Tests ◽  
Specific Band ◽  
Race 2

The diversity of races and prevalence of pathogenic populations of Fusarium oxysporum f. sp. dianthi (Fod) were surveyed in an area in southern Spain. From 54 farms, 132 isolates were collected from wilted carnation plants. Isolates were characterized by RAPD-PCR, DNA sequence analysis of the TEF1-α gene, and race-specific molecular markers. Selected isolates from RAPD groups were phenotypically evaluated by pathogenicity tests. Data analysis showed that Fod race 2 was the most frequent and prevalent race in the study area, followed by race 1/8. Moreover, phylogenetic analyses showed similar results, which were different to those of the race-specific PCR assays. It was concluded that (i) seven isolates were not classified in groups where Fod testers were clustered; even they showed different results when race-specific markers were used, (ii) ten isolates with retarded race 1 or race 8 specific band were characterized as F. proliferatum by TEF1-α gene sequencing and clustered into an outgroup, and (iii) six isolates failed to generate an amplification signal using race-specific markers. Furthermore, three of them were grouped close to race 2 tester according to the phylogenetic analyses, showing the same differential pathogenicity as race 2. This may indicate a Fod race 2 subgroup in this region.

scholarly journals Genetic Diversity and Identification of Wilt and Root Rot Pathogens of Tomato in China

Plant Disease ◽  
2020 ◽  
Vol 104 (6) ◽  
pp. 1715-1724
Author(s):  
Qingjing Ye ◽  
Rongqing Wang ◽  
Meiying Ruan ◽  
Zhuping Yao ◽  
Yuan Cheng ◽  
...  
Keyword(s):  
Root Rot ◽  
Management Strategies ◽  
Resistance Breeding ◽  
Its Region ◽  
Fusarium Equiseti ◽  
Resistant Varieties ◽  
Causative Agents ◽  
Race 1 ◽  
Pathogenicity Tests ◽  
Race 2

Fungal wilt and root rot diseases affecting tomato have become prevalent in China in recent years and have caused considerable damage. In 2016 to 2018, symptoms of putative wilt and root rot diseases were observed in several locations in tomato cultivars with resistance to Fusarium oxysporum f. sp. lycopersici races 1 and 2. The objective of this study was to identify the causative agents of wilt and root rot of tomato in China and provide a basis for disease prevention and resistance breeding programs. Based on DNA sequence analyses of the internal transcribed spacer (ITS) region, 91 isolates from the roots of tomato plants showing symptoms of wilt and root rot were identified, including F. oxysporum (64 isolates), Fusarium solani (11 isolates), Fusarium proliferatum (2 isolates), Fusarium graminearum (2 isolates), Fusarium equiseti (1 isolate), Pythium aphanidermatum (6 isolates), Ascomycota sp. (2 isolates), and Plectosphaerella cucumerina (3 isolates). F. oxysporum accounted for 70.33% of the isolates obtained. In this case, using PCR-based methods for differentiation of F. oxysporum, we identified several formae speciales and races of F. oxysporum: 7 isolates were identified as F. oxysporum f. sp. lycopersici race 1, 2 isolates as F. oxysporum f. sp. lycopersici race 2, 35 isolates as F. oxysporum f. sp. lycopersici race 3, and 13 isolates as F. oxysporum f. sp. radicis-lycopersici. Pathogenicity tests revealed 55 isolates of tomato wilt and root rot pathogens to be virulent. This study demonstrated that F. oxysporum f. sp. lycopersici race 3 was the most widespread and highly virulent race among these tomato pathogens in China, followed by F. oxysporum f. sp. radicis-lycopersici. Therefore, the development of resistant varieties of tomato against F. oxysporum f. sp. lycopersici race 3 and F. oxysporum f. sp. radicis-lycopersici would aid efforts to develop effective disease management strategies.

scholarly journals A Race-Specific Insertion of Transposable Element IS801 in Pseudomonas syringae pv. phaseolicola

1998 ◽  
Vol 11 (5) ◽  
pp. 423-428 ◽  
Author(s):  
A. I. González ◽  
M. L. Ruiz ◽  
C. Polanco
Keyword(s):  
Transposable Element ◽  
Pseudomonas Syringae ◽  
Restriction Analysis ◽  
Random Amplified Polymorphic Dna ◽  
Complete Sequence ◽  
Avirulence Gene ◽  
Reading Frame ◽  
Rapd Pcr ◽  
Race 1 ◽  
Race 2

The isolation and cloning of a random amplified polymorphic DNA-polymerase chain reaction (RAPD-PCR) band specific for Pseudomonas syringae pv. phaseolicola race 1 allowed us to design a pair of primers that amplify 1.2-kb race 1-specific and 2.7-kb race 2-specific fragments, providing a rapid method for the identification of races by standard PCR methods. Restriction analysis revealed identical endonuclease sites in both fragments but the race 2 fragment contains a 1.5-kb insertion, identified as transposable element IS801 by sequence comparison. One complete and one partial open reading frame (ORF), each with a high probability of encoding a protein, have been identified in the 1.2-kb fragment common to both race 1 and race 2 sequences. As IS801 disrupts the partial ORF in the race 2 fragment, the complete sequence of this ORF has been obtained as well as its promoter region. The possibility that it may encode an avirulence gene is discussed as well as the role of transposable elements in pathogen evolution.

Comparing vegetative compatibility and protein banding patterns for identification of Fusarium oxysporum f.sp. apii race 2

1991 ◽  
Vol 37 (9) ◽  
pp. 669-674 ◽  
Author(s):  
K. F. Toth ◽  
M. L. Lacy
Keyword(s):  
Fusarium Oxysporum ◽  
Polyacrylamide Gel Electrophoresis ◽  
Vegetative Compatibility ◽  
Wild Type ◽  
Banding Patterns ◽  
Formae Speciales ◽  
Compatibility Group ◽  
Race 1 ◽  
Pathogenicity Tests ◽  
Race 2

Vegetative compatibility grouping and electrophoretic separation of total proteins were compared as possible techniques for identifying isolates of Fusarium oxysporum f.sp. apii race 2, the cause of fusarium yellows of celery. Vegetative compatibility grouping was determined by pairing chlorate-tolerant, nitrate-nonutilizing mutants on a minimal medium containing nitrate as the sole nitrogen source. Heterokaryon formation, which resulted in wild-type growth, occurred only between mutants from vegetatively compatible isolates. All isolates of F. oxysporum f.sp. apii race 2 examined were placed within a unique vegetative compatibility group that excluded F. oxysporum f.sp. apii race 1 and the 11 other formae speciales of F. oxysporum tested. Few differences were observed in protein banding patterns among isolates of F. oxysporum f.sp. apii race 2, F. oxysporum f.sp. apii race 1, 11 other formae speciales of F. oxysporum, and 2 formae speciales of F. solani on 12% polyacrylamide gels. No banding pattern unique to F. oxysporum f.sp. apii race 2 was observed. Vegetative compatibility grouping could be accomplished more rapidly than greenhouse pathogenicity tests and more accurately identified race 2 isolates in a population of isolates of F. oxysporum from muck soils than did greenhouse pathogenicity tests or electrophoretic protein banding patterns. Key words: celery, fusarium yellows, nitrate-nonutilizing mutants, polyacrylamide gel electrophoresis.

scholarly journals Comparison of avrD alleles from Pseudomonas syringae pv. glycinea

1997 ◽  
Vol 10 (3) ◽  
pp. 416-422 ◽  
Author(s):  
Lisa Wolfson Keith ◽  
Carol Boyd ◽  
Noel T. Keen ◽  
J. E. Partridge
Keyword(s):  
Amino Acid ◽  
Pseudomonas Syringae ◽  
Functional Class ◽  
Avirulence Gene ◽  
Avirulence Genes ◽  
Indigenous Plasmids ◽  
Race 1 ◽  
Soybean Plants ◽  
Race 2 ◽  
Flanking Regions

Avirulence gene D alleles resided on indigenous plasmids in races 0, 2, 3, 4, 5, and 6 of Pseudomonas syringae pv. glycinea (Psg), but the allele in race 1 appeared to be chromosomal. These were all nonfunctional avirulence genes because they neither induced the avirulence phenotype on Rpg4 soybean cultivars nor directed the production of syringolide elicitors when expressed in Escherichia coli cells. The predicted proteins encoded by the seven Psg avrD genes were very similar to that of a functional class II allele from P. syringae pv. phaseolicola G50 race 2, but contained mutations collectively affecting only nine amino acid positions. Despite these relatively small amino acid differences and the location of avrD from each isolate on a 5.6-kb HindIII restriction fragment, the flanking regions varied considerably among the Psg isolates. The presence of avrD alleles with few alterations but different locational contexts in all tested Psg races argues that they provide an important selected function in the bacteria but have been modified to escape defense surveillance in Rpg4 soybean plants.

scholarly journals A New Race of Pseudomonas syringae pv. tabaci on Tobacco in Zimbabwe

Plant Disease ◽  
1998 ◽  
Vol 82 (12) ◽  
pp. 1404-1404 ◽  
Author(s):  
N. Mapuranga
Keyword(s):  
Pseudomonas Syringae ◽  
Leaf Spot ◽  
Treatment Resistance ◽  
Angular Leaf Spot ◽  
Ringer’S Solution ◽  
Fluorescent Pigment ◽  
Race 1 ◽  
Series Of Experiments ◽  
New Race ◽  
Race 2

Two forms of Pseudomonas syringae pv. tabaci cause wildfire (Tox+) and angular leaf spot (Tox-) diseases of tobacco in Zimbabwe. Two races of the pathogen (races 0 and 1) occur in Zimbabwe (4). Two groups of cultivars are available: one with resistance to race 0 only, tbe second with resistance to races 0 and 1 (4). P. syringae pv. tabaci was first observed on cultivars with resistance to races 0 and 1 in 1993, and infection on these cultivars is now widespread. The bacteria isolated from the infected plants were gram-negative rods and produced fluorescent pigment on King's medium B. Levan-oxidase-potato rot-arginine dihydrolase-tobacco hypersensitivity (LOPAT) tests indicated that the pathogen was a Group 1a pseudomonad (2). Pathogenicity and race designation for 58 isolates of the pathogen were determined on 8-week-old, greenhouse-raised tobacco plants. Inoculated plants were kept in controlled environment units (13/11 h photoperiod, 30 ± 2°C, relative humidity >75%) for 10 days. Pathogenicity was determined on cv. Kutsaga E1, which has no known resistance to any races of P. syringae pv. tabaci (4), and isolates from typical wildfire and angular leaf spot lesions were used for race designation by inoculating six plants of each indicator tobacco genotype. Genotypes included Nicotiana tabacum cv. Kutsaga E1 (susceptible to races 0, 1, and 2), which was used as the indicator genotype for race 0, N. longiflora (race 0 resistance) (1), N. tabacum cv. Kutsaga Mammoth 10 (resistance to race 0 derived from N. longiflora), N. rustica var. brasilea (resistance to races 0 and 1) (3,4), a breeding line, WZ 3-2-1-1, and cv. Kutsaga 35 (both resistant to races 0 and 1 with resistance derived from N. rustica var. brasilea). Six spots, three on either side of the midrib, were inoculated with an artist's airbrush (Aero-pro 251) operated at 250 kPa. The inoculum, (approximately 1 × 106 CFU/ml) suspended in a quarter-strength Ringer's solution was applied to one side of the midrib and Ringer's solution only to the other side, which served as control. Thirty-eight Tox+ isolates and 20 Tox- isolates were tested in a series of experiments in randomized complete blocks with four replications per treatment. Resistance to wildfire was characterized by localized chlorosis or whitish-tan hypersensitive lesions and susceptibility by necrotic lesions (>2 mm) surrounded by large chlorotic halos. Resistance to angular leaf spot was characterized by hypersensitive lesions or absence of symptoms and susceptibility by presence of symptoms (4). Sixty-six percent of the Tox+ isolates and 70% of the Tox- isolates successfully infected cultivars with known resistance to races 0 and 1, and were therefore designated race 2 (1). All other isolates were race 1. This is the first report of P. syringae pv. tabaci Tox+ and Tox- race 2 in Zimbabwe. References: (1) K. K. Knoche et al. Phytopathology 77:1364, 1987. (2). R. A. Lelliott and D. E. Stead. Methods in Plant Pathology. Vol. 2. 1987. (3). J. R. Stavely and H. A. Skoog. Proc. Am. Phytopathol. Soc. 3:231 (Abstr.), 1976. (4). J. J. Woodend and E. Mudzengerere. Euphytica 64:149, 1992.

scholarly journals DISTRIBUTION AND RACE COMPOSITION OF DOWNY MILDEW (Plasmopara halstedii (Farl.) Berl. and de Toni) IN BULGARIA / EXTENSION Y RAZAS DEL MILDIU (Plasmopara halstedii (Farl.) Berl. y de Toni) EN BULGARIA / ÉTENDUE ET RACES DE LA ROUILLE (Plasmopara halstedii (Farl.) Berl. and de Toni) EN BULGARIE

Helia ◽  
2000 ◽  
Vol 23 (33) ◽  
pp. 25-32
Author(s):  
P.S. Shindrova
Keyword(s):  
Downy Mildew ◽  
Resistance Gene ◽  
The Other ◽  
Plasmopara Halstedii ◽  
North West ◽  
North East ◽  
Race 1 ◽  
Race 2 ◽  
Production Areas ◽  
Number Of Authors

SUMMARY Downy mildew caused by the fungus Plasmopara halstedii is the main disease on sunflower in Bulgaria. In recent years a number of authors have reported the occurrence of new more virulent races of the pathogen. According to other authors these races demonstrate resistance to the fungicides used up to now. This fact is rather alarming and imposes the necessity of annual researches with the aim of following the changes in the downy mildew race variability. In the period 1995-1997 downy mildew isolates were collected from the following locations: Bourgas, Boyanovo, Karnobat, Ognyanovo, Selanovtsi, Kroushari, Lovech, Koubrat, Brashlyan, Sitovo, Tervel, Targovishte, IWS “Dobroudja” and Dobrich. The samples were assessed for virulence on a set of sunflower differential - lines under greenhouse conditions. The obtained results do not reveal a great race variability of downy mildew population in Bulgaria. In the period of study two races of the pathogen were identified: race 1 which infects the differential lines without genes for resistance to the pathogen. It is distributed in all sunflower production areas of the country. The other one is race 2. It is of limited distribution and has been registered in individual fields of north-east and north-west Bulgaria. It attacks the differential lines carrying the resistance gene Pl-1.

scholarly journals Induced Expression of Sarcotoxin IA Enhanced Host Resistance Against Both Bacterial and Fungal Pathogens in Transgenic Tobacco

2000 ◽  
Vol 13 (8) ◽  
pp. 860-868 ◽  
Author(s):  
Ichiro Mitsuhara ◽  
Hiroki Matsufuru ◽  
Masahiro Ohshima ◽  
Hisatoshi Kaku ◽  
Yuki Nakajima ◽  
...  
Keyword(s):  
Fungal Infection ◽  
Transgenic Tobacco ◽  
Pseudomonas Syringae ◽  
Host Resistance ◽  
Fungal Pathogens ◽  
Erwinia Carotovora ◽  
Induced Expression ◽  
Sarcotoxin Ia ◽  
Resistance To Infection

We demonstrate here that induced expression of sarcotoxin IA, a bactericidal peptide from Sarcophaga peregrina, enhanced the resistance of transgenic tobacco plants to both bacterial and fungal pathogens. The peptide was produced with a modified PR1a promoter, which is further activated by salicylic acid treatment and necrotic lesion formation by pathogen infection. Host resistance to infection of bacteria Erwinia carotovora subsp. carotovora and Pseudomonas syringae pv. tabaci was shown to be dependent on the amounts of sarcotoxin IA expressed. Since we found antifungal activity of the peptide in vitro, transgenic seedlings were also inoculated with fungal pathogens Rhizoctonia solani and Pythium aphanidermatum. Transgenic plants expressing higher levels of sarcotoxin were able to withstand fungal infection and remained healthy even after 4 weeks, while control plants were dead by fungal infection after 2 weeks.

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