Occurrence and Diversity of Xanthomonas campestris pv. campestris in Vegetable Brassica Fields in Nepal (original) (raw)
Related papers
Pesticidi i fitomedicina, 2012
Brassicas form the most important group of vegetable crops in Montenegro. The cabbage (Brassica oleracea var. capitata) is most commonly grown, although other brassicas, particularly kale, Brussels sprout, cauliflower and broccoli, have been increasingly produced since recently. One of the specialties of vegetable production in Montenegro is growing of collard (Brassica oleracea var. acephala), which is the simplest variety of the Brassica oleracea species and in the nearest relation with their wild ancestor - the sylvestris variety. Diseases are the main restrictive factors for successful production of these vegetables. Susceptibility of the cultivars and inadequate control often result in more or less damaged crops in some plots. Causal agents of brassica diseases, especially bacterial, have not been investigated in Montenegro until 2009. Since the symptoms observed in 2009 were ?V? shaped leaf edge necrosis and black rot of vascular tissue, it was assumed that they were caused by...
2013
Severe outbreaks of bacterial black rot caused by Xanthomonas campestris pv. campestris (Xcc) were observed in Brassica production fields of Southern Mozambique. The causal agent of the disease in the Mahotas and Chòkwé districts was identified and characterised. In total, 83 Xanthomonas-like strains were isolated from seed samples and leaves of cabbage and tronchuda cole with typical symptoms of the disease. Forty-six out of the 83 strains were found to be putative Xcc in at least one of the tests used: Classical biochemical assays, enzyme-linked immunosorbent assay (ELISA) with monoclonal antibodies, Biolog identification system, polymerase chain reaction (PCR) with specific primers and pathogenicity tests. The ELISA tests were positive for 43 strains. Biolog identified 43 strains as Xanthomonas, but only 32 as Xcc. PCR tests with primers targeting a fragment of the hrpF gene were positive for all 46 strains tested. Three strains were not pathogenic or weakly pathogenic and all other strains caused typical black rot symptoms in brassicas. Race type differentiation tests revealed the Xcc strains from Mozambique as members of race 1. The prevalence of this pathogenic race of the Xcc pathogen in Mozambique should be considered when black rot resistant cultivars are evaluated or introduced into the production regions of this country.
The genetic diversity of Xanthomonas campestris pv. campestris isolates from South Africa was evaluated using 28 isolates obtained from the Johannesburg Fresh Produce Market. Samples were collected from cabbage supplies from farms in Gauteng, Mpumalanga and North West Provinces. Strains were isolated from small sections of infected cabbage leaf samples and cultured on Yeast Dextrose Agar. Isolates identity was confirmed by ELISA and Pathogenicity test. Pathogenicity tests were performed by inoculating leaves of known susceptible cabbage seedlings. Infection symptoms induced could be categorized into three groups, ranging from typical to non-typical black rot symptoms. Four differential Brassica cultivars with known avirulence genes were used for race typing done by spray inoculation. Four races, namely 1, 3, 4 and 6, were identified. Of the 28 isolates, four were identified as race 1, two as race 3, 19 as race 4 and three as race 6. Repetitive DNA polymerase chain reaction-based fingerprinting using Eric- and Box-primers was used to assess the genetic diversity. Generated fingerprints of X. c pv. campestris were relatively similar. Cluster analysis could not strictly group isolates by their geographical origin, suggesting limited diversity of Xanthomonas campestris pv. campestris strains within cabbage producing regions in South Africa.
Diversity Among Strains of Xanthomonas campestris pv. vitians from Lettuce
Phytopathology®, 2003
Diversity in host range, pathogenicity, phenotypic characteristics, repetitive extragenic palindromic polymerase chain reaction (rep-PCR) profiles, and sequence of the 16S-23S rDNA spacer region was examined among 44 Xanthomonas strains isolated from lettuce. Forty-two of the strains were divided into two groups, designated A and B. Seventy percent were Group A, and most of the remaining strains including a reference strain (LMG 938) were Group B. Group A strains induced both local and systemic symptoms, whereas Group B strains caused only distinct necrotic spots. Two strains, including the X. campestris pv. vitians type strain, were distinct from the Group A and B strains and were not pathogenic on lettuce. Analysis of fatty acid profiles, serotype, carbon substrate utilization patterns, and protein fingerprints confirmed this grouping. The Group A and B strains also formed two unique clusters (I and II) by rep-PCR profiling that corresponded to the two groups. Direct sequencing of...
Journal of Plant Pathology, 2017
Xanthomonas campestris includes pathovars X. campestris pv. campestris, X. campestris pv. raphani and X. campestris pv. incanae, causing distinct diseases in Brassicaceae crops, ornamentals and weeds as well as on some Solanaceae crops. In Portugal, where brassica crops production has great economic importance, the presence of the first two pathovars was established. A polyphasic approach combining phenotypic, phylogenetic and genomic data was used to identify and characterize a set of 33 X. campestris isolates collected in Portugal. Pathogenicity tests on a wide host range demonstrated the presence of pathovar X. campestris pv. incanae for the first time in the country. Among X. campestris pv. campestris isolates, presence of races 4, 6 and 7 was recorded and two novel races of this pathovar, race 10 and race 11, were described. Phylogenetic relationships using gyrB gene confirmed phenotypic identification at species level and grouped X. campestris isolates in clades mostly congrue...
Plant Disease
Mustard (Brassica juncea L.) is an important oil seed crop in the Brassicaceae family. It is widely cultivated in India for its edible leaves, oil and medicinal properties. In January 2022, we noticed necrotic symptoms typical black rot disease on Brassica juncea (L.) cv. Pusa Bold grown in Indian Agricultural Research Institute, India. Initially, chlorotic lesions emerged on the leaf margin, which progressed to angular V-shaped necrotic lesions and blackened veins. Disease progression became a necrotic appearance in the leaf results browning and papery leaf texture appeared. The suspected causal agent was isolated from three different diseased plants of Pusa Bold on nutrient sucrose agar medium that formed pale yellow, mucoid, and fluidal colonies. Three representative isolates originated from three different plants were sub-cultured on YGCA medium. These isolates are Gram-negative, oxidase negative, KOH positive, nonfluorescent on King’s Medium B agar, and positive for starch hydr...
Plant Disease
Xanthomonas campestris pv. campestris is a causative agent of black rot disease of cruciferous crops. A whole-genome sequence of any race of X. campestris pv. campestris has not been reported from India. The isolate Xcc-C7, race 4, of X. campestris pv. campestris was isolated from cabbage (Brassica oleracea var. capitata) from Bengaluru, in the southern parts of India. Whole-genome sequence data were generated by the next-generation sequencingbased single-molecule real-time sequencing (SMRT) techniques. This study will improve our knowledge of genomic diversity in X. campestris pv. campestris and pave the way for research on host-pathogen interactions (crucifer crops-X. campestris pv. campestris) to develop resistance in cultivated Brassicaceae crops. X. campestris pv. campestris (Pammel) Dowson is a Gram-negative, rod-shaped pathogenic bacterium that causes black rot disease in many cruciferous crops, worldwide. It is a vascular disease developing 'V'-shaped yellow lesions accompanied by blackened veins at margin of the leaf (Fig. 1A). It is genetically diversified by the specific host range of crucifer crops, including B. oleracea vegetables (cole crops such as cabbage, cauliflower, brussels sprout, broccoli, knoll khol, and kale), oilseed crops, ornamentals, and weeds (Singh et al. 2016; Vicente et al. 2001). The annual worldwide spread of black rot disease limits the yield of cole crops under favorable conditions (Singh and Dhar 2011; Singh et al. 2014). The diversity within X. campestris pv. campestris is reported by several researchers (Jensen et al. 2010; Singh and Dhar 2011; Singh et al. 2016). In fact, the pathovar is subdivided into nine races based on host-pathogen interactions (Vicente et al. 2001). According to Singh et al. (2016), only races 1, 4, and 6 of X. campestris pv. campestris of crucifer crops have been identified in India, with races 1 and 4 occurring predominately worldwide. Races 2, 3, and 5 seem to be rare (