Persistence and Recovery of Endophytic Erwinia Amylovora in Apparently Healthy Apple Tissues

Ge, Q. X.; Zwet, T. van der

doi:10.17660/actahortic.1996.411.8

Cited by 7 publications

(6 citation statements)

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“…In addition, no symptoms are observed in winter in deciduous species, and the surveys, made mainly by visual detection of typical lesions, are useless. Apparent healthy plants can carry latent infections (5,8,23,43), and from these E. amylovora could be distributed from nurseries to other parts of the country or other countries, where it will only take favorable conditions for symptoms to develop. As pointed out by other authors, in spite of being a very useful and sensitive technique, PCR is still seriously limited due to inhibition by different compounds (13,23,27,32).…”

Section: Discussionmentioning

confidence: 99%

“…Workshop Fire Blight, p. 30,1998). E. amylovora can survive as an endophyte and an epiphyte (5,8,17), and its systemic distribution in plants has been demonstrated (28,36). This has prompted in the last years an increasing interest for reliable and sensitive methods to analyze potentially infected but symptomless plant material, because the inadvertent introduction of infected plants to pathogen-free areas could result in the unstoppable spread of E. amylovora (10).…”

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confidence: 99%

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Development of a Highly Sensitive Nested-PCR Procedure Using a Single Closed Tube for Detection of Erwinia amylovora in Asymptomatic Plant Material

Llop

Bonaterra

Peñalver

et al. 2000

Appl Environ Microbiol

127

109

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A novel method, which involves a nested PCR in a single closed tube, was developed for the sensitive detection of Erwinia amylovora in plant material. The external and internal primer pairs used had different annealing temperatures and directed the amplification of a specific DNA fragment from plasmid pEA29. The procedure involved two consecutive PCRs, the first of which was performed at a higher annealing temperature that allowed amplification only by the external primer pair. Using pure cultures of E. amylovora, the sensitivity of the nested PCR in one tube was similar to that of a standard nested PCR in two tubes. The specificity and sensitivity were greater than those of standard PCR procedures that used a single primer pair. The presence of inhibitors in plant material, very common in E. amylovora hosts, is overcome with this system in combination with a simple DNA extraction protocol because it eliminates many of the inhibitory compounds. In addition, it needs a very small sample volume (1 l of DNA extracted). With 83 samples of naturally infected material, this method achieved better results than any other PCR technique: standard PCR detected 55% of positive samples, two-tube nested PCR detected 71% of positive samples, and nested PCR in a single closed tube detected 78% of positive samples. When analyzing asymptomatic plant material, the number of positive samples detected by the developed nested PCR was also the highest, compared with the PCR protocols indicated previously (17, 20, and 25% of 251 samples analyzed, respectively). This method is proposed for the detection of endophytic and epiphytic populations of E. amylovora in epidemiological studies and for routine use in quarantine surveys, due to its high sensitivity, specificity, speed, and simplicity.

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Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

Development of a Highly Sensitive Nested-PCR Procedure Using a Single Closed Tube for Detection of Erwinia amylovora in Asymptomatic Plant Material

Llop

Bonaterra

Peñalver

et al. 2000

Appl Environ Microbiol

127

109

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“…No other workers have reported direct or indirect evidence of phloem migration in growing shoots. Ge & van der Zwet (1996), Momol et al. (1998), Hickey et al.…”

Section: Phloem Migrationmentioning

confidence: 99%

“…No other workers have reported direct or indirect evidence of phloem migration in growing shoots. Ge & van der Zwet (1996), Momol et al (1998), Hickey et al (1999 and Agrios (2004) considered that the phloem migration evidence was valid. However, Momol et al (1998) were sometimes working with 3-year-old stems, so migration in secondary phloem tissue was a possibility there, especially late in the season.…”

Section: Vascular Wilt Diseasementioning

confidence: 99%

Fire blight. Why do views on host invasion by Erwinia amylovora differ?

Billing¹

2010

Plant Pathology

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The fire blight pathogen, Erwinia amylovora, commonly infects flowers and shoots of certain rosaceous hosts and systemic (whole‐tree) invasion sometimes follows. The bacterium may be found in the parenchyma of bark tissue and/or in mature xylem vessels of stem tissue. Views differ on initial sites of multiplication and the optimal route for systemic migration. This article presents the evidence on which the different views are based. There are limited observations on orchard pear and apple trees; in most experimental studies, young apple shoots on potted plants were used. Tissue maturity at the site of shoot inoculation is of prime importance. If xylem vessels are damaged, inoculum may be sucked into the vessels and the bacteria will multiply there. In younger tissue, there is less suction pressure. The critical stem entry site for the invasion of cortical parenchyma seems to be near or above the most recently unfolded leaf. No one has suggested that migration in bark tissue cannot be a major route. If the xylem route is followed, the pathogen needs a means of escape into bark tissue, where typical symptoms develop; means of escape from mature xylem vessels have not been demonstrated and remain a matter for speculation. Published evidence does not seem to support the idea that fire blight is a vascular wilt disease, nor that the extracellular polysaccharide produced by E. amylovora is a toxin and responsible for the wilting symptom seen in the early stages of the disease.

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“…Gowda and Goodman detected E. amylovora 70 cm below the stem apex 2 weeks after inoculation, and bacteria were found well in advance of visible symptoms (7). E. amylovora was recovered from symptomless side shoots of 20% of Red Jonathan-M.7 trees grown in the greenhouse for about 10 months after inoculation (6). E. amylovora can also be resident in symptomless apple and pear tissue, which may explain the unexpected appearance of fire blight disease in nurseries, young plantings, and bearing orchards (10).…”

mentioning

confidence: 99%

Internal Movement of Erwinia amylovora Through Symptomless Apple Scion Tissues into the Rootstock

Momol¹,

Norelli²,

Piccioni³

et al. 1998

Plant Disease

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Shoot tips of potted Empire and Golden Delicious trees on the susceptible dwarfing rootstock M.26 in the greenhouse were injected with inoculum containing 5 × 109 CFU/ml Erwinia amylovora. At intervals after inoculation, trees were sampled at increments between the shoot tip and the roots by excising stem segments. Segments were ground in phosphate buffer and assayed for the presence of E. amylovora by plating on semi-selective medium and by a polymerase chain reaction (PCR)-based detection method. Eleven days after inoculation, E. amylovora was detected by PCR in symptomless scion tissue >50 cm below the shoot-tip in Empire and Golden Delicious, and in 2-year-old tissue in Golden Delicious. By 21 days, E. amylovora was detected in the M.26 rootstock of Empire trees, and by 41 days in the M.26 rootstock of Golden Delicious. In a similar experiment the following year, Empire trees on M.26 rootstock were inoculated with E. amylovora at early (16 May), mid- (11 June), and late (6 July) phenophase of shoots. Three weeks after inoculation, E. amylovora was detected by PCR from M.26 rootstocks of five of six plants inoculated at the late phenophase, compared to zero of six plants inoculated at the early or mid-phenophase. Late-season fire blight infections of the scion may be particularly hazardous for the health of the rootstock.

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Persistence and Recovery of Endophytic Erwinia Amylovora in Apparently Healthy Apple Tissues

Cited by 7 publications

References 0 publications

Development of a Highly Sensitive Nested-PCR Procedure Using a Single Closed Tube for Detection of Erwinia amylovora in Asymptomatic Plant Material

Development of a Highly Sensitive Nested-PCR Procedure Using a Single Closed Tube for Detection of Erwinia amylovora in Asymptomatic Plant Material

Fire blight. Why do views on host invasion by Erwinia amylovora differ?

Internal Movement of Erwinia amylovora Through Symptomless Apple Scion Tissues into the Rootstock

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