scholarly journals Characterization of Xanthomonas campestris pv. campestris in Algeria

2021 ◽  
Vol 60 (1) ◽  
pp. 51-62
Author(s):  
Samia LAALA ◽  
Sophie CESBRON ◽  
Mohamed KERKOUD ◽  
Franco VALENTINI ◽  
Zouaoui BOUZNAD ◽  
...  

Xanthomonas campestris pv. campestris (Xcc) causes the black rot of cruciferous plants. This seed-borne bacterium is considered as the most destructive disease to cruciferous crops. Although sources of contamination are various, seeds are the main source of transmission. Typical symptoms of black rot were first observed in 2011 on cabbage and cauliflower fields in the main production areas of Algeria. Leaf samples displaying typical symptoms were collected during 2011 to 2014, and 170 strains were isolated from 45 commercial fields. Xcc isolates were very homogeneous in morphological, physiological and biochemical characteristics similar to reference strains, and gave positive pathogenicity and molecular test results (multiplex PCR with specific primers). This is the first record of Xcc in Algeria. Genetic diversity within the isolates was assessed in comparison with strains isolated elsewhere. A multilocus sequence analysis based on two housekeeping genes (gyrB and rpoD) was carried out on 77 strains representative isolates. The isolates grouped into 20 haplotypes defined with 68 polymorphic sites. The phylogenetic tree obtained showed that Xcc is in two groups, and all Algerian strains clustered in group 1 in three subgroups. No relationships were detected between haplotypes and the origins of the seed lots, the varieties of host cabbage, the years of isolation and agroclimatic regions.

2007 ◽  
Vol 97 (7) ◽  
pp. 803-812 ◽  
Author(s):  
A. Ignatov ◽  
A. Sechler ◽  
E. L. Schuenzel ◽  
I. Agarkova ◽  
B. Oliver ◽  
...  

Xanthomonas campestris pv. campestris (X. campestris) infects a large number of cruciferous plants, including weeds. California has one of the largest and most diverse populations of wild cruciferous plants in the world. Although considerable information is available on the genetic diversity of X. campestris in commercial crop plants, nothing is known about the diversity in strains infecting weeds. To assess the genetic diversity among strains of X. campestris in weeds in noncultivated and cultivated areas, strains of the pathogen were isolated from populations of cruciferous weeds growing in coastal valley crop-production sites and from remote nonproduction sites along the California central coast. Results of fingerprinting over 68 strains using amplified fragment length polymorphism along with representative strains by sequence analysis showed the presence of seven genotypes. Genotypes A and B were limited to coastal sites; genotypes C, D, and E were from inland cultivated sites; and genotypes F and G were present in both coastal noncultivated and inland cultivated sites. Crop strains were grouped outside any weed strain group and were separated from the weed strains and other pathovars of X. campestris. These results revealed, for the first time, that strains of X. campestris present in noncultivated coastal weed populations generally were unique to a site and genetically distinct from strains present in populations of weeds in crop-production areas located nearby.


2017 ◽  
Vol 83 (6) ◽  
pp. 373-381 ◽  
Author(s):  
Hirofumi Nagai ◽  
Noriyuki Miyake ◽  
Shinro Kato ◽  
Daisuke Maekawa ◽  
Yasuhiro Inoue ◽  
...  

1999 ◽  
Vol 30 (3) ◽  
pp. 191-195 ◽  
Author(s):  
Sayonara M.P. Assis ◽  
Rosa L.R. Mariano ◽  
Sami J. Michereff ◽  
Gil Silva ◽  
Elizabeth A.A. Maranhão

Twenty yeast isolates, obtained from cabbage phylloplane, were evaluated for antagonistic activity against Xanthomonas campestris pv. campestris, in field. Plants of cabbage cv. Midori were pulverized simultaneously with suspensions of antagonists and pathogen. After 10 days, plants were evaluated through percentage of foliar area with lesions. Percentage of disease severity reduction (DSR%) was also calculated. Yeast isolates LR32, LR42 and LR19 showed, respectively, 72, 75 and 79% of DSR. These antagonists were tested in seven different application periods in relation to pathogen inoculation (T1=4 d before; T2=simultaneously; T3=4 d after; T4=4 d before + simultaneously; T5=4 d after + simultaneously; T6=4 d before + 4 d after; T7=4 d before + simultaneously + 4 d after). The highest DSRs were showed by LR42 (71%), LR42 (67%), LR35 (69%) and LR19 (68%) in the treatments T7, T4, T5 and T6, which significantly differed from the others. The same yeast antagonists were also tested for black rot control using different cabbage cultivars (Fuyutoyo, Master-325, Matsukaze, Midori, Sekai I and Red Winner). The DSRs varied from 58 to 61%, and there was no significant difference among cultivars.


2008 ◽  
Vol 21 (8) ◽  
pp. 1128-1138 ◽  
Author(s):  
Wei Qian ◽  
Zhong-Ji Han ◽  
Jun Tao ◽  
Chaozu He

The gram-negative bacterium Xanthomonas campestris pv. campestris is the causal agent of black rot disease of cruciferous plants. Its genome encodes a large repertoire of two-component signal transduction systems (TCSTSs), which consist of histidine kinases and response regulators (RR) to monitor and respond to environmental stimuli. To investigate the biological functions of these TCSTS genes, we aimed to inactivate all 54 RR genes in X. campestris pv. campestris ATCC 33913, and successfully generated 51 viable mutants using the insertion inactivation method. Plant inoculation identified two novel response regulator genes (XCC1958 and XCC3107) that are involved in virulence of this strain. Genetic complementation demonstrated that XCC3107, designated as vgrR (virulence and growth regulator), also affects bacterial growth and activity of extracellular proteases. In addition, we assessed the survival of these mutants under various stresses, including osmotic stress, high sodium concentration, heat shock, and sodium dodecyl sulfate exposure, and identified a number of genes that may be involved in the general stress response of X. campestris pv. campestris. Mutagenesis and phenotypic characterization of RR genes in this study will facilitate future studies on signaling networks in this important phytopathogenic bacterium.


2000 ◽  
Vol 78 (9) ◽  
pp. 1144-1149 ◽  
Author(s):  
P A Gay ◽  
S Tuzun

The physiological mechanisms associated with resistance of cabbage to black rot disease seem to be associated with the hydathodes. To investigate the role of hydathodes in disease resistance, total peroxidase activities, anionic peroxidase isozyme expression, and lignin deposition were determined in hydathodes of resistant (Hancock and Green Cup), partially resistant (Cheers), and susceptible (Strukton and Perfect Ball) cabbage varieties (Brassica oleracea L.) during pathogenesis with Xanthomonas campestris pv. campestris. Four-week-old plants were petiole-inoculated with a highly virulent strain of X. campestris pv. campestris (FD91L). Hydathodal fluids were collected daily over a 14-day period from infected plants as well as noninfected, mock-inoculated control plants. Hydathodal fluids of resistant varieties had greater peroxidase activity when compared to susceptible ones, with infected plants having higher peroxidase levels than noninfected plants. Isoelectric focusing revealed the presence of four anionic peroxidase isozymes in hydathodal fluids, with the most anionic one (pI of 3.6) accumulating only upon infection. Lignin deposition in and around the hydathodes was associated with the accumulation of this particular isozyme in hydathodal fluids. The evidence suggests that a rapid, systemic response is associated with resistance to the bacterial pathogen.Key words: peroxidases, hydathodes, isozymes, black rot disease, cabbage, Xanthomonas campestris pv. campestris.


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