Ingress of <i>Clavibacter michiganensis</i> subsp. <i>michiganensis</i> into Tomato Leaves Through Hydathodes

Carlton, W. M.; Braun, E. J.; Gleason, Mark L.

doi:10.1094/phyto.1998.88.6.525

Cited by 107 publications

(67 citation statements)

References 9 publications

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“…sepedonicus thrives almost exclusively as a plant endophyte, while C. michiganensis subsp. michiganensis is both an endophyte and an epiphyte, the comparative genome studies should also provide insight into aspects of niche adaptation (17,18,51,77). Whole-genome comparisons also were used to identify genomic events associated with the evolution of host specificity and therefore subspeciation within C. michiganensis.…”

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Genome of the Actinomycete Plant Pathogen Clavibacter michiganensis subsp. sepedonicus Suggests Recent Niche Adaptation

et al. 2008

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Clavibacter michiganensis subsp. sepedonicus is a plant-pathogenic bacterium and the causative agent of bacterial ring rot, a devastating agricultural disease under strict quarantine control and zero tolerance in the seed potato industry. This organism appears to be largely restricted to an endophytic lifestyle, proliferating within plant tissues and unable to persist in the absence of plant material. Analysis of the genome sequence of C. michiganensis subsp. sepedonicus and comparison with the genome sequences of related plant pathogens revealed a dramatic recent evolutionary history. The genome contains 106 insertion sequence elements, which appear to have been active in extensive rearrangement of the chromosome compared to that of Clavibacter michiganensis subsp. michiganensis. There are 110 pseudogenes with overrepresentation in functions associated with carbohydrate metabolism, transcriptional regulation, and pathogenicity. Genome comparisons also indicated that there is substantial gene content diversity within the species, probably due to differential gene acquisition and loss. These genomic features and evolutionary dating suggest that there was recent adaptation for life in a restricted niche where nutrient diversity and perhaps competition are low, correlated with a reduced ability to exploit previously occupied complex niches outside the plant. Toleration of factors such as multiplication and integration of insertion sequence elements, genome rearrangements, and functional disruption of many genes and operons seems to indicate that there has been general relaxation of selective pressure on a large proportion of the genome.High-GϩC-content gram-positive coryneform bacteria cause economic losses in several crops worldwide, yet the relatively slow in vitro and in planta growth and general genetic intractability of these bacteria have long been deterrents to successful identification of the specific molecular mechanisms by which they cause diseases in plants. Consequently, there is a clear disparity between the amount of scientific research on plant-pathogenic coryneform bacteria and the amount of scientific research on their gramnegative counterparts. Recent advances in this field have coincided with the availability of transformation systems and complete genome sequences for representatives of the genera Clavibacter and Leifsonia, two of the major coryneform plant-pathogenic genera (14,32,48,56,74). Importantly, these advances allowed breakthrough identification of a novel set of pathogenicity-related genes in the tomato pathogen Clavibacter michiganensis subsp. michiganensis and identification of homologues in other coryneform plant pathogens (15, 27, 32; see the accompanying paper). Because methodologies created for functional analysis of C. michiganensis subsp. michiganensis are generally applicable to other members of the genus, additional advances in this field can be expected in the near future (40, 46).The genus Clavibacter provides an excellent resource for obtaining a more comprehensive underst...

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Genome of the Actinomycete Plant Pathogen Clavibacter michiganensis subsp. sepedonicus Suggests Recent Niche Adaptation

et al. 2008

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“…These observations and conclusions were supported by previous reports showing that early canker symptoms appeared on the cotyledons and stems and that epiphytic C. michiganensis subsp. michiganensis populations were associated with tomato leaves (2,19,40). Perhaps one of the most important features of using a bioluminescent C. michiganensis subsp.…”

Section: Discussionmentioning

confidence: 99%

Bioluminescence Imaging ofClavibacter michiganensissubsp.michiganensisInfection of Tomato Seeds and Plants

Xiao¹,

Miller²,

Baysal-Gurel³

et al. 2010

Appl Environ Microbiol

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Clavibacter michiganensis subsp. michiganensis is a Gram-positive bacterium that causes wilting and cankers, leading to severe economic losses in commercial tomato production worldwide. The disease is transmitted from infected seeds to seedlings and mechanically from plant to plant during seedling production, grafting, pruning, and harvesting. Because of the lack of tools for genetic manipulation, very little is known regarding the mechanisms of seed and seedling infection and movement of C. michiganensis subsp. michiganensis in grafted plants, two focal points for application of bacterial canker control measures in tomato. To facilitate studies on the C. michiganensis subsp. michiganensis movement in tomato seed and grafted plants, we isolated a bioluminescent C. michiganensis subsp. michiganensis strain using the modified Tn1409 containing a promoterless lux reporter. A total of 19 bioluminescent C. michiganensis subsp. michiganensis mutants were obtained. All mutants tested induced a hypersensitive response in Mirabilis jalapa and caused wilting of tomato plants. Real-time colonization studies of germinating seeds using a virulent, stable, constitutively bioluminescent strain, BL-Cmm17, showed that C. michiganensis subsp. michiganensis aggregated on hypocotyls and cotyledons at an early stage of germination. In grafted seedlings in which either the rootstock or scion was exposed to BL-Cmm17 via a contaminated grafting knife, bacteria were translocated in both directions from the graft union at higher inoculum doses. These results emphasize the use of bioluminescent C. michiganensis subsp. michiganensis to help better elucidate the C. michiganensis subsp. michiganensis-tomato plant interactions. Further, we demonstrated the broader applicability of this tool by successful transformation of C. michiganensis subsp. nebraskensis with Tn1409::lux. Thus, our approach would be highly useful to understand the pathogenesis of diseases caused by other subspecies of the agriculturally important C. michiganensis.

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“…Two milliliter of each bacterial suspension (1 9 10 8 cfu/ml) was infiltrated to the leaves of 1 month old tobacco plant (Nicotiana tabacum L.) for hypersensitivity tests, with water as a controls (Carlton et al 1998). Infiltrated tobacco plants were maintained under green house conditions with 25-30°C in day and 15-18°C at night and were maintained until the symptoms appeared.…”

Section: Pathogenicity Assay and Hypersensitivity Testsmentioning

confidence: 99%

Reconnaissance of the Bronze Age Site in the Southern Lake Urmia Basin, Northwest of Iran: Ali Abad Tape

Faraji¹,

Zadeh²,

Mahadevaiah³

2015

Asia. Jour. Rese. Soci. Scie. and Human.

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Ralstonia solanacearum is a causative agent of bacterial wilt in many economically important crops, and Xanthomonas perforans is the causal organism of bacterial spot, one of the most important diseases of vegetables. A multiplex PCR protocol has been developed for the simultaneous, specific and rapid identification of R. solanacearum and X. perforans in plant materials. Speciesspecific primers RS-F-759 and RS-R-760 for R. solanacearum, RST2 and RST3 for X. perforans were used for identification of both pathogens at primer concentrations of 1:4 by optimization of multiplex PCR at annealing temperature of about 61 ± 1°C. With these primer sets, specific amplification of 281-and 840-bp PCR products was obtained for R. solanacearum and X. perforans, respectively. The multiplex PCR assay was validated with susceptible plants mechanically inoculated with both the pathogens; specific PCR products confirmed the presence of R. solanacearum and X. perforans. The multiplex PCR is valuable in identification as well as primary screening of cultivars of both pathogens. The present study is a rapid and easy method for early identification of pathogens from asymptomatic and symptomatic plant materials.

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Ingress of Clavibacter michiganensis subsp. michiganensis into Tomato Leaves Through Hydathodes

Cited by 107 publications

References 9 publications

Genome of the Actinomycete Plant Pathogen Clavibacter michiganensis subsp. sepedonicus Suggests Recent Niche Adaptation

Genome of the Actinomycete Plant Pathogen Clavibacter michiganensis subsp. sepedonicus Suggests Recent Niche Adaptation

Bioluminescence Imaging ofClavibacter michiganensissubsp.michiganensisInfection of Tomato Seeds and Plants

Reconnaissance of the Bronze Age Site in the Southern Lake Urmia Basin, Northwest of Iran: Ali Abad Tape

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