The relationship of ammonia to symptom expression in apple shoots inoculated with <i>Erwinia amylovora</i>

Lovrekovich, L.; Lovrekovich, H.; Goodman, R. N.

doi:10.1139/b70-140

Cited by 10 publications

(3 citation statements)

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“…We are now attempting to locate more definitely the regions, chromosomal or extrachromosomal, which determine plant virulence. Such refinements are expected to provide bases for evaluating the several proposed mechanisms (8,9,11,12) pertaining to the virulence of E. amylovora for plants.…”

Section: Ea178-m173s-v14mentioning

confidence: 99%

“…Erwinia amylovora (Burrill) Winslow et al, the bacterium causing fire blight disease of pears and apples, affects a wide range of plants within the family Rosaceae (6). Although considerable effort has been expended in attempts to clarify the mechanism(s) of plant virulence in this economically significant plant pathogen, there is as yet no certainty about the precise virulence factors associated with the production of disease symptoms (7)(8)(9)(10)(11)(12)14). Initially, Goodman and collaborators (9,11,12) suggested that ammonia produced by E. amylovora might alter adversely the structure of the plant membrane protein and thus behave as a necrotoxin.…”

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confidence: 99%

“…Although considerable effort has been expended in attempts to clarify the mechanism(s) of plant virulence in this economically significant plant pathogen, there is as yet no certainty about the precise virulence factors associated with the production of disease symptoms (7)(8)(9)(10)(11)(12)14). Initially, Goodman and collaborators (9,11,12) suggested that ammonia produced by E. amylovora might alter adversely the structure of the plant membrane protein and thus behave as a necrotoxin. More recently, Goodman and Huang (8) reported the isolation of a toxin (amylovorin) from apple fruit tissues infected by Erwinia amylovora. According to them, amylovorin is a polymer of galactose (98%) with 0.375% protein and traces of unidentified substances.…”

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confidence: 99%

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Conjugational transfer of genes determining plant virulence in Erwinia amylovora

Pugashetti¹,

Starr²

1975

J Bacteriol

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A stable virulent donor strain (EA178R,-99) of Erwinia amylovora can transfer, by conjugation during a 3-h mating period, the gene or genes which determine(s) plant virulence to avirulent recipient strains (EA178-M64S and EA178-M173S) of E. amylovora. The virulence of over 200 recombinant clones was tested; they all were as virulent on immature Bartlett pear fruits (and, in the smaller series of strains tested, also on Pyracantha twigs) as was the parent donor strain. Although the avirulent recipient strains are amino acid auxotrophs, addition of the required amino acids to the inocula in plant virulence trials does not of itself restore virulence. Two small series of prototrophic revertant clones were selected from the auxotrophic avirulent recipient strains; only nine of the 21 prototrophic revertant clones regained virulence, whereas the other 12 prototrophic revertant clones remained avirulent, again suggesting a lack of parallelism between nutritional status and virulence in this system. Preliminary interrupted mating trials, carried out at 15-min intervals over 3 h, show that ser is transferred during the first 15 min, that pro starts entering at about 75 min (and with a higher frequency later), and that lac (originating from an integrated Escherichia coli F'lac) enters toward the end of the 3-h mating period and at a reduced frequency compared-to the other markers. The gene or genes which determine(s) plant virulence in this E. amylovora donor strain appear(s) to be transferred readily and seemingly completely to recipient strains during the first 15 min of a 3-h mating period. Exposure of the virulent donor strain to acridine orange or ethidium bromide does not result in loss of virulence, suggesting (but, of course, not proving conclusively) that the determinant(s) of virulence in E. amylovora might be chromosomal rather than extrachromosomal.

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Section: Ea178-m173s-v14mentioning

confidence: 99%