Articles
SURVIVAL OF ERWINIA AMYLOVORA IN DEAD APPLE LEAF TISSUE
Article number
1056_8
Pages
71 – 75
Language
English
Abstract
To elucidate the possibility of Erwinia amylovora survival in dead host plant tissue a study was conducted during two seasons (2011/12 and 2012/13) using apple trees Idared/M26 growing in pots placed in an insect cage with mesh walls and a glass roof.
Tips of actively growing terminal shoots were inoculated by cutting just below the first undeveloped leaf, using scissors previously immersed in a water suspension of the highly virulent wild strain Ea 659 of E. amylovora containing 107 CFU/ml.
After 4-5 weeks fire blight affected all shoots and leaves, and spread on to the woody shoots.
Five, six, seven, and eight months after inoculation samples of entirely necrotized leaf tissue were collected for a study on the presence of bacteria in the midrib, lateral veins, and parenchyma.
Using conventional methods living E. amylovora cells were detected in almost all samples from the midrib, in some of them from lateral veins but never in parenchyma.
However, their presence in these tissues was confirmed by applying a nested PCR method that detected both living and dead bacterial cells.
An analysis of the metabolic activity in the studied leaves, using Evans blue staining and observations with a light microscope performed five months after inoculation, showed that some of the tissue cells were still alive.
However, a similar analysis conducted seven and eight months after inoculation confirmed that the leaf cells were dead.
Our study indicated that E. amylovora can survive not only as a biotroph or epiphyte, but also as a necrotroph or seminecrotroph.
Tips of actively growing terminal shoots were inoculated by cutting just below the first undeveloped leaf, using scissors previously immersed in a water suspension of the highly virulent wild strain Ea 659 of E. amylovora containing 107 CFU/ml.
After 4-5 weeks fire blight affected all shoots and leaves, and spread on to the woody shoots.
Five, six, seven, and eight months after inoculation samples of entirely necrotized leaf tissue were collected for a study on the presence of bacteria in the midrib, lateral veins, and parenchyma.
Using conventional methods living E. amylovora cells were detected in almost all samples from the midrib, in some of them from lateral veins but never in parenchyma.
However, their presence in these tissues was confirmed by applying a nested PCR method that detected both living and dead bacterial cells.
An analysis of the metabolic activity in the studied leaves, using Evans blue staining and observations with a light microscope performed five months after inoculation, showed that some of the tissue cells were still alive.
However, a similar analysis conducted seven and eight months after inoculation confirmed that the leaf cells were dead.
Our study indicated that E. amylovora can survive not only as a biotroph or epiphyte, but also as a necrotroph or seminecrotroph.
Publication
Authors
P. Sobiczewski, A. Mikiciński, B. Dyki
Keywords
Malus × domestica, Erwinia amylovora, detection, necrotroph
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