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Using hydroponics and novel non-destructive pot culture systems which enable inoculation at specific tuber development stages, the dynamics of common scab infection patterns in potato were studied in order to provide more precise identification of tuber physiological factors associated with susceptibility. At the whole-tuber level, infection percentages were greatest when Streptomyces scabiei inoculation occurred early; at 2 weeks after tuberization (WAT) 68% of tubers became infected, contrasting with late inoculation (8 WAT), when only 4% infection occurred. The first-formed internodes were most susceptible to infection, whilst later-forming and slower-expanding internodes were less susceptible. Detailed tuber physiological examination of internode 2 showed that pathogen-induced changes, including increased phellem (periderm) thickness, cell layers and phellem suberization (key physiological features believed critical to S. scabiei infection) were promoted through S. scabiei inoculation. Sequential harvesting showed enhanced phellem suberization (28% greater than the control) within 7 days of pathogen exposure, while phellem thickness and layer responses were also initiated early in the infection process (10–14 days after pathogen exposure) and these responses were independent of symptom expression. Differences in cultivar response were observed, with greater phellem suberization observed 10 days after tuberization (DAT) in the common-scab-tolerant cv. Russet Burbank than in the susceptible cv. Desiree. Likewise, Russet Burbank had thicker and more numerous cell layers in the phellem (up to eight cell layers) during early tuber growth (20–30 DAT) than Desiree (up to six cell layers).

Item Type:	Refereed Article
Keywords:	hydroponics;infection window;inoculation;soil-less media;Solanum tuberosum;Streptomyces scabiei
Research Division:	Agricultural, Veterinary and Food Sciences
Research Group:	Horticultural production
Research Field:	Horticultural crop growth and development
Objective Division:	Plant Production and Plant Primary Products
Objective Group:	Horticultural crops
Objective Field:	Stone fruit (excl. avocado)
UTAS Author:	Khatri, BB (Mr Bhim Khatri)
UTAS Author:	Tegg, RS (Dr Robert Tegg)
UTAS Author:	Brown, PH (Professor Phil Brown)
UTAS Author:	Wilson, CR (Professor Calum Wilson)
ID Code:	67257
Year Published:	2011
Web of Science® Times Cited:	34
Deposited By:	Agricultural Science
Deposited On:	2011-03-01
Last Modified:	2015-01-27
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