Variant somaclones of potato cultivar Russet Burbank, selected for resistance to common scab using in vitro cell selection techniques, were tested for resistance to powdery scab, another important disease of potato caused by Spongospora subterranea. This pathogen also invades roots, producing root galls. Most variants consistently showed increased resistance to powdery scab, both in field and glasshouse challenge, when compared to the parental cultivar, several significantly so. On average, the best variant reduced powdery scab incidence by 51% and severity (tuber surface coverage) by 64%. In contrast, no improvement in the extent of root infection and root galling was seen. These results suggest host interactions during root and tuber infection are distinct. Correlation analyses of disease indices amongst the selected variants showed no association between Sp. subterranea root infection and gall scores, nor between root infection and tuber disease severity. However, a weak positive association was found between root gall score and tuber disease, and a strong correlation between tuber disease incidence and severity scores. Interestingly, positive correlations were also found between the extent of powdery and common scab resistance expressed and both incidence and severity of these diseases within the variants, suggesting a common defence mechanism. The role of thaxtomin A in selecting for concurrent resistance to both diseases is discussed.

Item Type:	Refereed Article
Keywords:	root disease, Russet Burbank, Spongospora subterranea, tuber disease
Research Division:	Agricultural and Veterinary Sciences
Research Group:	Horticultural Production
Research Field:	Horticultural Crop Protection (Pests, Diseases and Weeds)
Objective Division:	Plant Production and Plant Primary Products
Objective Group:	Horticultural Crops
Objective Field:	Vegetables
UTAS Author:	Tegg, RS (Dr Robert Tegg)
UTAS Author:	Thangavel, T (Dr Tamil Thangavel)
UTAS Author:	Wilson, CR (Professor Calum Wilson)
ID Code:	79824
Year Published:	2012
Web of Science® Times Cited:	13
Deposited By:	Agricultural Science
Deposited On:	2012-10-04
Last Modified:	2015-06-25
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