PCR-based determination of colonization patterns during potato tuber infection by single and multiple pathogens |
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| Authors: | A El Hadrami O Wally L R Adam F Daayf |
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| Institution: | (1) Department of Plant Science, University of Manitoba, 222 Agriculture Building, R3T 2N2 Winnipeg, Manitoba, Canada |
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| Abstract: | Potato tubers piled in storage are prone to infection by numerous pathogens. Each pathogen can cause damage alone, but severe
losses often arise when more than one pathogen is involved. Currently, only a visual diagnosis is practiced on potato tubers
before storing them, which does not allow any prediction of further disease spread. The aim of the present study was to determine
differences in patterns of tissue colonization by several tuber decay pathogens and how late blight infection affects further
tuber colonization by other important tuber pathogens. This study was conducted using artificial inoculation of potato tubers
and PCR to provide an early and accurate diagnosis of disease development for major potato tuber rots, and to assess potential
synergism/antagonism between Phytophthora infestans and other pathogens in stored tubers. In order to accurately follow the progress of each pathogen in tuber tissues, samples
were collected over time from both the surface (peel, 0–2 mm depth) and internal tissues (flesh, depth > 2 mm) of the tubers
at various distances from the inoculation site, at 3, 5, 7, 10, 12, 14, 17, and 19 days after inoculation. Successful detection
of single or multiple pathogens was achieved using specific PCR-primers for each pathogen. Pathogens were always detected
several centimeters ahead of the visible lesions. This tracking enabled us to determine the extent of colonization both on
the tuber’s surface and in internal tissues by each tested pathogen, either after single or multiple infections involving
P. infestans as the primary pathogen. The presence of P. infestans was shown to enhance the development of Pectobacterium atrosepticum and to slow down that of P. erythrospetica and Pythium ultimum. No noticeable effect on further tuber colonization by F. sambucinum, V. dahliae or V. albo-atrum was observed in the presence of P. infestans. This approach involving more than one pathogen is more realistic than classical studies considering single pathogens, and
may be helpful in monitoring the sanitary status of stored tubers. Our results make the outcome of certain combinations of
pathogens in potato tubers more predictable and may result in more efficient preventive measures. |
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| Keywords: | Pathogen dynamics Potato tuber rot Storage Single and multiple infections PCR |
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