A Serious Outbreak of Race 6 of Xanthomonas campestris pv. vesicatoria on Pepper in Southern Florida

In the 1997-1998 winter vegetable season, a widespread and serious outbreak of bacterial spot occurred on pepper in commercial fields throughout southern Florida. This was the first serious epidemic of bacterial spot on pepper in southern Florida since the 1993-1994 season. Cultivars affected included those with resistance to races 1–3 of X. campestris pv. vesicatoria, commonly found in previous Florida surveys (1). Field sampling designs, isolation methods, and pathogen identification were carried out as previously described (1). Twenty-seven fields were sampled in Palm Beach, St. Lucie, Martin, Broward, and Collier counties. The race of each strain was determined by infiltration of 3.0 × 108 CFU per ml of sterile tap water suspension into Early Calwonder and three near-isogenic lines of Early Calwonder with genes for vertical resistance to specific races of the pathogen. Test plants were maintained in the greenhouse and observed for hypersensitive and disease reactions over several days. Of a total of 244 X. campestris pv. vesicatoria strains collected, 73.4% were identified as race 6 and 10.2% as race 4. Irrespective of the presence of resistance genes in cultivars sampled, race 6 (eastern Florida) and race 4 (southwestern Florida) predominated in this study. Copper tolerance was widespread among X. campestris pv. vesicatoria strains of all races, with 91% of the strains showing tolerance to 250 g per ml of CuSO4 · 5H2O incorporated into 0.5% (wt/vol) glucose-nutrient agar. Selection pressure resulting from widespread planting of race 1, 2, 3-resistant cultivars may have contributed to this outbreak. High disease pressure also may be related to the unusually wet winter. Rainfall accumulation from December 1997 through March 1998 was 25.6 cm above normal. Reference: (1) K. Pohronezny et al. Plant Dis. 76:118, 1992.

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Occurrence and Diversity of Xanthomonas campestris pv. campestris in Vegetable Brassica Fields in Nepal

Plant Disease ◽

10.1094/pdis-94-3-0298 ◽

2010 ◽

Vol 94 (3) ◽

pp. 298-305 ◽

Cited By ~ 26

Author(s):

Brita Dahl Jensen ◽

Joana G. Vicente ◽

Hira K. Manandhar ◽

Steven J. Roberts

Keyword(s):

Xanthomonas Campestris ◽

Mustard Seed ◽

Black Rot ◽

Brassica Spp ◽

Mustard Plant ◽

Race 1 ◽

Polymerase Chain ◽

Race 4 ◽

Xanthomonas Campestris Pv Campestris ◽

Vegetable Brassica

Black rot caused by Xanthomonas campestris pv. campestris was found in 28 sampled cabbage fields in five major cabbage-growing districts in Nepal in 2001 and in four cauliflower fields in two districts and a leaf mustard seed bed in 2003. Pathogenic X. campestris pv. campestris strains were obtained from 39 cabbage plants, 4 cauliflower plants, and 1 leaf mustard plant with typical lesions. Repetitive DNA polymerase chain reaction-based fingerprinting (rep-PCR) using repetitive extragenic palindromic, enterobacterial repetitive intergenic consensus, and BOX primers was used to assess the genetic diversity. Strains were also race typed using a differential series of Brassica spp. Cabbage strains belonged to five races (races 1, 4, 5, 6, and 7), with races 4, 1, and 6 the most common. All cauliflower strains were race 4 and the leaf mustard strain was race 6. A dendrogram derived from the combined rep-PCR profiles showed that the Nepalese X. campestris pv. campestris strains clustered separately from other Xanthomonas spp. and pathovars. Race 1 strains clustered together and strains of races 4, 5, and 6 were each split into at least two clusters. The presence of different races and the genetic variability of the pathogen should be considered when resistant cultivars are bred and introduced into regions in Nepal to control black rot of brassicas.

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Control of Bacterial Spot on Tomato in the Greenhouse and Field with H-mutant Bacteriophages

HortScience ◽

10.21273/hortsci.35.5.882 ◽

2000 ◽

Vol 35 (5) ◽

pp. 882-884 ◽

Cited By ~ 66

Author(s):

J.E. Flaherty ◽

G.C. Somodi ◽

J.B. Jones ◽

B.K. Harbaugh ◽

L.E. Jackson

Keyword(s):

Chemical Control ◽

Xanthomonas Campestris ◽

Bacterial Spot ◽

Water Control ◽

Tomato Seedling ◽

Manganese Zinc ◽

Progress Curve ◽

Race 1 ◽

Field Season ◽

Early Vigor

A mixture of host-range mutant (h-mutant) bacteriophages specific for tomato race 1 (T1) and race 3 (T3) of the bacterial spot pathogen, Xanthomonas campestris pv. vesicatoria (Doidge) Dye was evaluated for biological control of bacterial spot on `Sunbeam' tomato (Lycopersicon esculentum Mill.) transplants and field-grown plants for two seasons (Fall 1997 and Fall 1998). Foliar applications of bacteriophages were compared with similar applications of water (control) and of copper/mancozeb bactericides, the commonly used chemical control strategy for tomato seedling and field production. In 1997, the incidence of bacterial spot on greenhouse-grown seedlings was reduced from 40.5% (control) to 5.5% or 0.9% for bactericide- or bacteriophage-treated plants, respectively. In 1998, the incidence of bacterial spot was 17.4% on control plants vs. 5.5% and 2.7% for bactericide- and bacteriophage-treated plants, respectively, although these differences were not statistically significant at P ≤ 0.05. Applications of bacteriophages to field-grown tomatoes decreased disease severity as measured by the area under the disease progress curve (AUDPC) by 17.5% (1997) and 16.8% (1998) compared with untreated control plants. Preharvest plant vigor ratings, taken twice during each field season, were higher in the bacteriophage-treated plants than in either bactericide-treated plants or nontreated controls except for the early vigor rating in 1998. Use of bacteriophages increased total weight of extra-large fruit 14.9% (1997) and 24.2% (1998) relative to that of nontreated control plants, and 37.8% (1997) and 23.9% (1998) relative to that of plants treated with the chemical bactericides. Chemical names used: manganese, zinc, carboxyethylene bis dithiocarbamate (mancozeb).

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Identification of Sources of Resistance to Xanthomonas campestris pv. campestris in Brassica napus Crops

Plant Disease ◽

10.1094/pdis-06-10-0428 ◽

2011 ◽

Vol 95 (3) ◽

pp. 292-297 ◽

Cited By ~ 4

Author(s):

M. Lema ◽

P. Soengas ◽

P. Velasco ◽

M. Francisco ◽

M. E. Cartea

Keyword(s):

Brassica Napus ◽

Xanthomonas Campestris ◽

Specific Resistance ◽

Sources Of Resistance ◽

Nonspecific Resistance ◽

Breeding Programs ◽

Race 1 ◽

Improved Cultivars ◽

Race 4 ◽

Xanthomonas Campestris Pv Campestris

Black rot, caused by Xanthomonas campestris pv. campestris, is one of the most important diseases affecting Brassica crops worldwide. Nine races have been differentiated in X. campestris pv. campestris, with races 1 and 4 being the most virulent and widespread. The objective of this work was to identify sources of resistance to races 1 and 4 of X. campestris pv. campestris in different Brassica napus crops, mainly in the underexplored pabularia group. Seventy-six accessions belonging to four B. napus groups were screened for resistance to two X. campestris pv. campestris races (1 and 4). The strain of race 1 used in this study was more virulent on the tested materials than the strain of race 4. No race-specific resistance was found to race 1. Most cultivars were susceptible except Russian kale, from the pabularia group, which showed some resistant plants and some other accessions with some partially resistant plants. High levels of race-specific resistance to race 4 were found in the pabularia group, and great variability within accessions was identified. Three improved cultivars (Ragged Jack kale, Friese Gele, and Valle del Oro) and four landraces (Russian kale, MBG-BRS0037, MBG-BRS0041, and MBG-BRS0131) showed plants with some degree of resistance to both races, which may indicate that race-nonspecific resistance is involved. These accessions could be directly used in breeding programs, either as improved cultivars or as donors of race-specific resistance to other Brassica cultivars.

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Copper Tolerance in Australian Populations of Xanthomonas campestris pv. vesicatoria Contributes to Poor Field Control of Bacterial Spot of Pepper

Plant Disease ◽

10.1094/pdis.2004.88.9.921 ◽

2004 ◽

Vol 88 (9) ◽

pp. 921-924 ◽

Cited By ~ 25

Author(s):

Heidi L. Martin ◽

Vicki A. Hamilton ◽

Rosemary A. Kopittke

Keyword(s):

Strong Evidence ◽

Regression Models ◽

Xanthomonas Campestris ◽

Copper Concentration ◽

Copper Tolerance ◽

Bacterial Spot ◽

Poor Control ◽

Field Control ◽

Two Populations ◽

Copper Tolerant

Many Australian pepper producers have reported poor control of bacterial spot of pepper (caused by Xanthomonas campestris pv. vesicatoria) despite using copper bactericides at recommended rates. This prompted us to investigate whether copper-tolerant strains of the pathogen are present in Australia and whether they are a contributing factor to poor control. We screened strains of X. campestris pv. vesicatoria in the laboratory, in broths containing different concentrations of CuSO4, and established the maximum copper concentration at which each strain could grow. About one in four strains (75 total) collected between 1999 and 2000 tolerated ≥1.0 mM CuSO4 and could be considered copper tolerant. Only one strain (of 12) collected before 1987 could tolerate 1.0 mM, and comparison of the two populations by fitting regression models revealed that the mortality of strains in the two populations differed significantly across all concentrations of copper. It was necessary to apply higher rates of copper to strains collected between 1999 and 2000 to achieve mortality levels equivalent to those in the older population. This is strong evidence that the prevalence of copper-tolerant strains has increased in Australian populations. We also assessed whether copper-tolerant strains may increase substantially in a field population of X. campestris pv. vesicatoria when copper is repeatedly sprayed. In the field, the proportion of copper-tolerant strains increased after 12 weekly sprays of copper, and they were very prevalent in the population after 21 sprays. This is the first report of copper tolerance in Australian populations of X. campestris pv. vesicatoria.

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Identification of Crucifer Accessions from the NC-7 and NE-9 Plant Introduction Collections That Are Resistant to Black Rot (Xanthomonas campestris pv. campestris) Races 1 and 4

HortScience ◽

10.21273/hortsci.44.2.284 ◽

2009 ◽

Vol 44 (2) ◽

pp. 284-288 ◽

Cited By ~ 7

Author(s):

Phillip D. Griffiths ◽

Laura Fredrick Marek ◽

Larry D. Robertson

Keyword(s):

Xanthomonas Campestris ◽

Plant Introduction ◽

Black Rot ◽

Sources Of Resistance ◽

Race 1 ◽

Incomplete Resistance ◽

Serious Disease ◽

Race 4 ◽

Interspecific Crossing ◽

Xanthomonas Campestris Pv Campestris

Black rot, caused by Xanthomonas campestris pv. campestris (Pam.) Dawson (Xcc), is a serious disease of vegetable crucifers worldwide. The USDA NC-7 and NE-9 regional PI stations maintain vegetable, mustard, and oilseed crucifers, of which 4084 accessions were available for testing, representing 23 genera and 125 species. These accessions were evaluated for resistance to black rot after wound inoculation with race 1 of the pathogen. Accessions that were symptomless for race 1 of Xcc were replanted and inoculated with race 4 of the pathogen to identify accessions with resistance to both races. Symptomless responses were observed in 362 accessions of the mustard species (Brassica juncea, Brassica carinata, and Brassica nigra), in particular, B. juncea for which 353 of the 389 accessions tested were symptomless. Resistance was identified in five accessions of B. carinata out of 63 evaluated (PI 193460, PI 193959, PI 194254, PI 280230, PI 633077) determined by repeated symptomless responses after inoculation and four accessions of B. nigra from the 83 evaluated (PI 197401, A 25399, A 25401, PI 458981). Five accessions of Brassica rapa (PI 633154, A9285, PI 340208, PI 597831, PI 173847) were identified, which represent promising new sources of resistance to Xcc. Incomplete resistance was identified in an accession of Eruca sativa (PI 633207), an accession of Lepidium spp. (PI 633265), an accession of Sinapis arvensis (PI 296079), and two accessions of B. napus (PI 469733 and PI 469828). These identified accessions represent germplasm that can be used in breeding for resistance to Xcc in vegetable crucifers through interspecific crossing.

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Genome Sequences of the Race 1 and Race 4 Xanthomonas campestris pv. campestris Strains CFBP 1869 and CFBP 5817

Genome Announcements ◽

10.1128/genomea.01023-15 ◽

2015 ◽

Vol 3 (5) ◽

Cited By ~ 5

Author(s):

Stéphanie Bolot ◽

Aude Cerutti ◽

Sébastien Carrère ◽

Matthieu Arlat ◽

Marion Fischer-Le Saux ◽

...

Keyword(s):

Economic Impact ◽

Xanthomonas Campestris ◽

Draft Genome ◽

Causal Agent ◽

Black Rot ◽

Genome Sequences ◽

Race 1 ◽

Race 4 ◽

Xanthomonas Campestris Pv Campestris

Xanthomonas campestris pv. campestris is the causal agent of black rot on Brassicaceae . The draft genome sequences of strains CFBP 1869 and CFBP 5817 have been determined and are the first ones corresponding to race 1 and race 4 strains, which have a predominant agronomic and economic impact on cabbage cultures worldwide.

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Analysis of Sequenced Genomes of Xanthomonas perforans Identifies Candidate Targets for Resistance Breeding in Tomato

Phytopathology ◽

10.1094/phyto-03-16-0119-fi ◽

2016 ◽

Vol 106 (10) ◽

pp. 1097-1104 ◽

Cited By ~ 18

Author(s):

Sujan Timilsina ◽

Peter Abrahamian ◽

Neha Potnis ◽

Gerald V. Minsavage ◽

Frank F. White ◽

...

Keyword(s):

Resistance Breeding ◽

Effector Protein ◽

Bacterial Disease ◽

Bacterial Spot ◽

Genome Sequences ◽

Xanthomonas Perforans ◽

Modern Agriculture ◽

Rapid Changes ◽

Pathogen Populations ◽

Race 4

Bacterial disease management is a challenge for modern agriculture due to rapid changes in pathogen populations. Genome sequences for hosts and pathogens provide detailed information that facilitates effector-based breeding strategies. Tomato genotypes have gene-for-gene resistance to the bacterial spot pathogen Xanthomonas perforans. The bacterial spot populations in Florida shifted from tomato race 3 to 4, such that the corresponding tomato resistance gene no longer recognizes the effector protein AvrXv3. Genome sequencing showed variation in effector profiles among race 4 strains collected in 2006 and 2012 and compared with a race 3 strain collected in 1991. We examined variation in putative targets of resistance among Florida strains of X. perforans collected from 1991 to 2006. Consistent with race change, avrXv3 was present in race 3 strains but nonfunctional in race 4 strains due to multiple independent mutations. Effectors xopJ4 and avrBs2 were unchanged in all strains. The effector avrBsT was absent in race 3 strains collected in the 1990s but present in race 3 strains collected in 2006 and nearly all race 4 strains. These changes in effector profiles suggest that xopJ4 and avrBsT are currently the best targets for resistance breeding against bacterial spot in tomato.

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Development of Bacterial Spot on Near-Isogenic Lines of Bell Pepper Carrying Gene Pyramids Composed of Defeated Major Resistance Genes

Phytopathology ◽

10.1094/phyto.1999.89.11.1066 ◽

1999 ◽

Vol 89 (11) ◽

pp. 1066-1072 ◽

Cited By ~ 18

Author(s):

C. S. Kousik ◽

D. F. Ritchie

Keyword(s):

Disease Severity ◽

Resistance Genes ◽

Field Studies ◽

Residual Effects ◽

Specific Gene ◽

Near Isogenic Lines ◽

Bacterial Spot ◽

Isogenic Lines ◽

Major Resistance Genes ◽

Race 4

Disease severity caused by races 1 through 6 of Xanthomonas campestris pv. vesicatoria on eight near-isogenic lines (isolines) of Early Calwonder (ECW) with three major resistance genes (Bs1, Bs2, and Bs3) in different combinations was evaluated in the greenhouse and field. Strains representing races 1, 3, 4, and 6 caused similar high levels of disease severity, followed by races 2 and 5 on susceptible ECW. Race 3 caused severe disease on all isolines lacking resistance gene Bs2. Race 4, which defeats Bs1 and Bs2, caused less disease on isoline ECW-12R (carries Bs1 + Bs2), than on isolines ECW, ECW-10R (carries Bs1), and ECW-20R (carries Bs2). Similar results were obtained with race 4 strains in field studies conducted during 1997 and 1998. In greenhouse studies, race 6, which defeats all three major genes, caused less disease on isoline ECW-13R (carries Bs1 + Bs3) and ECW-123R (carries Bs1 + Bs2 + Bs3) than on isolines ECW, ECW-10R, ECW-20R, and ECW-30R (carries Bs3), but not on ECW-23R (carries Bs2 + Bs3). In greenhouse studies with commercial hybrids, strains of races 4 and 6 caused less disease on Boynton Bell (carries Bs1 + Bs2) than on Camelot (carries no known resistance genes), King Arthur (carries Bs1), and X3R Camelot (carries Bs2). Race 6 caused less disease on hybrid R6015 (carries Bs1 + Bs2 + Bs3) and Sentinel (carries Bs1 + Bs3) than on Camelot. Residual effects were not as evident in field studies with race 6 strains. Defeated major resistance genes deployed in specific gene combinations (i.e., gene pyramids) were associated with less area under the disease progress curve than when genes were deployed individually in isolines of ECW or commercial hybrids. Successful management of bacterial spot of pepper is achieved incrementally by integrating multiple tactics. Although there is evidence of residual effects from defeated genes, these effects alone likely will not provide acceptable bacterial spot control in commercial production fields. However, when combined with sanitation practices and a judicious spray program, pyramids of defeated resistance genes may aid in reducing the risk of major losses due to bacterial spot.

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