Ammonia as a necrotoxin in the hypersensitive reaction caused by bacteria in tobacco leaves

1970 ◽  
Vol 48 (1) ◽  
pp. 167-171 ◽  
Author(s):  
L. Lovrekovich ◽  
H. Lovrekovich ◽  
R. N. Goodman
Keyword(s):  
Erwinia Amylovora ◽  
Hypersensitive Reaction ◽  
Tissue Necrosis ◽  
Ammonia Gas ◽  
Tobacco Leaves

Tobacco leaves inoculated with 108 cells/ml of the incompatible bacteria Pseudomonas pisi, P. syringae, P. lachrymans, or Erwinia amylovora developed hypersensitive tissue necrosis, on the first day after inoculation. Similar tissue necrosis developed on the leaves inoculated with the compatible bacterium P. tabaci on the second day. By the time the symptoms developed ammonia gas had evolved from the inoculated leaves. Tissue necrosis caused by bacteria could be reproduced by exposing healthy tobacco leaves to ammonia gas. The amount of ammonia evolved during the development of either the hypersensitive reactions or the disease was enough to account for the formation of tissue necrosis in tobacco.

Resistance in plants to bacteria

1972 ◽  
Vol 181 (1064) ◽  
pp. 247-266 ◽  
Keyword(s):  
Induced Resistance ◽  
Host Plants ◽  
Pathogenic Bacteria ◽  
Erwinia Amylovora ◽  
Soft Rot ◽  
Hypersensitive Reaction ◽  
Corn Stalk ◽  
Tobacco Leaves ◽  
Stalk Rot ◽  
Protective Reaction

The number of different interaction combinations between bacteria and plants and the diversity of types of bacteria with respect to mode of pathogenesis indicate that plants possess various mechanisms for resistance to bacteria. On the basis of present evidence, bacteria may be prevented from causing disease in plants by one of two types of resistance system: constitutive or induced. Constitutive systems may involve: (1) inhibition of bacteria by pre-formed compounds that are toxic per se or which are converted rapidly to toxic products when cells are injured; or (2) a combination of adverse physiological factors that currently remain ill-defined. Among examples cited, details are presented of recent research concerning the possible role of a constitutive system in the resistance of corn to soft rot bacteria in the genus Erwinia . Corn (maize) plants which were highly susceptible to one pathotype of E . chrysanthemi were found to be highly resistant to other pathotypes of E. chrysanthemi and to other species of Erwinia . A differentially inhibitory fraction (d.i.f.) extracted from corn plants was more toxic to soft rot Erwinia spp. than to the corn-stalk rot pathogen. Other plant pathogenic bacteria that do not attack corn and certain (but not all) saprophytic bacteria tested were also inhibited by the d.i.f. In contrast, all of the bacterial corn pathogens that were tested were similar to the corn-stalk rot pathogen in their relative insensitivity to d.i.f. Studies with the arbutin-hydroquinone complex in Pyrus spp. also provide evidence for a constitutive type of system for resistance to Erwinia amylovora . However encouraging recent investigators of these types of systems may be, unequivocal demonstration of the specific manner in which a preformed system operates in vivo is still needed. Induced resistance systems include: (1) the hypersensitive reaction (h.r.), and (2) the protection response. The h.r. is elicited by most phytopathogenic bacteria (in particular, pseudomonads, xanthomonads and Erwinia amylovora ) when introduced into non-host plants, but not by most saprophytic bacteria. Recent studies of different races and strains of the wilt pathogen, Pseudomonas solanacearum , as well as with other bacteria, indicate that there are certain exceptions to the generalization that pathogenic bacteria, or avirulent variants of pathogens, will induce a hypersensitive reaction in non-host plants. Isolates of the banana race of P. solanacearum (non-pathogenic to tobacco) consistently induced an h.r. in tobacco leaves; whereas the potato race (also non-pathogenic to tobacco) did not produce this reaction. The second main type of induced resistance, the protective reaction, can be induced by prior infiltration of the inoculation court with living cells of avirulent or incompatible strains and, in some instances, saprophytes. It can be induced also by heat-killed cells of bacterial pathogens. Aspects of the protective reaction have been examined with various isolates of P. solanacearum . Infiltration of tobacco leaves with heat-killed cells of the wilt pathogen before infiltration with cells of the banana strain (non-pathogenic on tobacco) prevented the h.r. from developing. It was also possible by this treatment to prevent the virulent tobacco strain from infecting the leaf. The protective response, which was light dependent, was detected in areas adjacent to infiltrated tissues and in other adjacent leaves 2-3 days after treatment. Similar effects were obtained with a relatively heat-stable protein fraction obtained from cells of an avirulent strain of P. solanacearum . Recent advances in studies with bacterial pathogens reveal the possibilities of using these systems in order to gain new insight into the nature of resistance to pathogens in general.

scholarly journals The hrpC and hrpN Operons of Erwinia chrysanthemi EC16 Are Flanked by plcA and Homologs of Hemolysin/Adhesin Genes and Accompanying Activator/Transporter Genes

1998 ◽  
Vol 11 (6) ◽  
pp. 563-567 ◽  
Author(s):  
Jihyun F. Kim ◽  
Jong Hyun Ham ◽  
David W. Bauer ◽  
Alan Collmer ◽  
Steven V. Beer
Keyword(s):  
Pseudomonas Syringae ◽  
Erwinia Amylovora ◽  
Hypersensitive Reaction ◽  
Erwinia Chrysanthemi ◽  
Tobacco Leaves

The hrpC operon of Erwinia chrysanthemi EC16 encodes five genes conserved in Erwinia amylovora and Pseudomonas syringae. Mutagenesis indicated that hrcC is required for elicitation of the hypersensitive reaction in tobacco leaves. The unexpected presence of plcA and homologs of hemolysin/activator genes in the regions flanking the hrcC and hrpN operons is reported.

scholarly journals Flagellin Glycosylation Island in Pseudomonas syringae pv. glycinea and Its Role in Host Specificity

2003 ◽  
Vol 185 (22) ◽  
pp. 6658-6665 ◽  
Author(s):  
Kasumi Takeuchi ◽  
Fumiko Taguchi ◽  
Yoshishige Inagaki ◽  
Kazuhiro Toyoda ◽  
Tomonori Shiraishi ◽  
...  
Keyword(s):  
Pseudomonas Syringae ◽  
Posttranslational Modification ◽  
Hypersensitive Reaction ◽  
Amino Acid Sequences ◽  
Open Reading Frames ◽  
Tobacco Leaves ◽  
Flagellin Glycosylation ◽  
The Difference ◽  
Soybean Leaves ◽  
Reading Frames

ABSTRACT The deduced amino acid sequences of the flagellins of Pseudomonas syringae pv. tabaci and P. syringae pv. glycinea are identical; however, their abilities to induce a hypersensitive reaction are clearly different. The reason for the difference seems to depend on the posttranslational modification of the flagellins. To investigate the role of this posttranslational modification in the interactions between plants and bacterial pathogens, we isolated genes that are potentially involved in the posttranslational modification of flagellin in P. syringae pv. glycinea (glycosylation island); then defective mutants with mutations in these genes were generated. There are three open reading frames in the glycosylation island, designated orf1, orf2, and orf3. orf1 and orf2 encode putative glycosyltransferases, and mutants with defects in these open reading frames, Δorf1 and Δorf2, secreted nonglycosylated and slightly glycosylated flagellins, respectively. Inoculation tests performed with these mutants and original nonhost tobacco leaves revealed that Δorf1 and Δorf2 could grow on tobacco leaves and caused symptom-like changes. In contrast, these mutants failed to cause symptoms on original host soybean leaves. These data indicate that putative glycosyltransferases encoded in the flagellin glycosylation island are strongly involved in recognition by plants and could be the specific determinants of compatibility between phytopathogenic bacteria and plant species.

scholarly journals First Report of Fire Blight on Pyrus elaeagrifolia and Amelanchier sp. in Bulgaria

Plant Disease ◽  
2007 ◽  
Vol 91 (1) ◽  
pp. 110-110 ◽  
Author(s):  
S. G. Bobev ◽  
J. Van Vaerenbergh ◽  
M. Maes
Keyword(s):  
Fire Blight ◽  
Erwinia Amylovora ◽  
Hypersensitive Reaction ◽  
Sterile Water ◽  
First Report ◽  
Progressive Necrosis ◽  
Park Area ◽  
First Time ◽  
Pyrus Elaeagrifolia ◽  
Positive Results

In 2005, a fire blight epidemic occurred for the second time within the last 3 years, and severe damages were observed on pome fruits trees in many regions of Bulgaria. For the first time, we found fire blight on Pyrus elaeagrifolia and Amelanchier sp. grown in a park area (Plovdiv Region), providing evidence of continuing spread of the pathogen in Bulgaria. The symptoms on P. elaeagrifolia were necrotic, immature fruitlets and progressive necrosis toward the adjacent branches, thus forming cankers and leading to death of the plant above the canker. Many Amelanchier sp. shrubs had severely blighted flowers, fruitlets, shoots, and branches and dried, amber ooze droplets on the shoots. All the isolations made from blighted hosts' shoots and cankers on King's medium B (2 to 3 days, 26 to 27°C) yielded whitish, glistening, round bacterial colonies. Infiltration of the suspensions of randomized isolates from both hosts into tobacco leaves resulted in a typical hypersensitive reaction. Subsequently, some strains showed a typical ooze production on immature pear fruits (cv. Conference) and were also successfully reisolated from artificially inoculated quince shoots (1.2 × 109 CFU, cv. Portugalska, three replicates), where typical fire blight symptoms were observed, thereby fulfilling Koch's postulates. No symptoms or bacteria were found within any of the shoots from the same plant species injected with sterile water. The identity of the isolates was confirmed as Erwinia amylovora by an antibody-based slide agglutination test (Neogen_Express; Neogen Europe, Ltd., UK) and PCR test with primers derived from the ams region (1). On the basis of the symptoms, cultural characteristics, and positive results in pathogenicity, serological, and PCR tests, the isolates were considered to be E. amylovora. To our knowledge, this is the first report of fire blight on P. elaeagrifolia and Amelanchier sp. in Bulgaria. Reference: (1) S. Bereswill et al. Appl. Environ. Microbiol. 61:2636, 1995.

scholarly journals HrpW of Erwinia amylovora, a New Harpin That Contains a Domain Homologous to Pectate Lyases of a Distinct Class

1998 ◽  
Vol 180 (19) ◽  
pp. 5203-5210 ◽  
Author(s):  
Jihyun F. Kim ◽  
Steven V. Beer
Keyword(s):  
Plant Cell Wall ◽  
Erwinia Amylovora ◽  
Pectate Lyase ◽  
Hypersensitive Reaction ◽  
Host Tissue ◽  
Wild Type ◽  
Pectate Lyases ◽  
Heat Stable ◽  
Lyase Activity ◽  
Type Strains

ABSTRACT Harpins, such as HrpN of Erwinia amylovora, are extracellular glycine-rich proteins that elicit the hypersensitive reaction (HR). We identified hrpW of E. amylovora, which encodes a protein similar to known harpins in that it is acidic, rich in glycine and serine, and lacks cysteine. A putative HrpL-dependent promoter was identified upstream ofhrpW, and Western blot analysis of hrpL mutants indicated that the production of HrpW is regulated by hrpL. HrpW is secreted via the Hrp (type III) pathway based on analysis of wild-type strains and hrp secretion mutants. When infiltrated into plants, HrpW induced rapid tissue collapse, which required active plant metabolism. The HR-eliciting activity was heat stable and protease sensitive. Thus, we concluded that HrpW is a new harpin. HrpW of E. amylovora consists of two domains connected by a Pro and Ser-rich sequence. A fragment containing the N-terminal domain was sufficient to elicit the HR. Although no pectate lyase activity was detected, the C-terminal region of HrpW is homologous to pectate lyases of a unique class, suggesting that HrpW may be targeted to the plant cell wall. Southern analysis indicated that hrpW is conserved among several Erwiniaspecies, and hrpW, provided in trans, enhanced the HR-inducing ability of a hrpN mutant. However, HrpW did not increase the virulence of a hrpN mutant in host tissue, and hrpW mutants retained the wild-type ability to elicit the HR in nonhosts and to cause disease in hosts.

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