European Journal of Plant Pathology (2011) 129, 637-651

Yared Tesfai Tewoldemedhin, Mark Mazzola, Lizel Mostert and Adéle McLeod (2011)
Cylindrocarpon species associated with apple tree roots in South Africa and their quantification using real-time PCR
European Journal of Plant Pathology 129 (4), 637-651
Abstract: Cylindrocarpon species are known to be a component of the pathogen/pest complex that incites apple replant disease. In South Africa, no information is available on apple associated Cylindrocarpon species and their pathogenicity. Therefore, these aspects were investigated. Among the isolates recovered from apple roots in South Africa, four species (C. destructans, C. liriodendri, C. macrodidymum and C. pauciseptatum) were identified using β-tubulin gene sequencing and phylogenetic analysis. This is the first report of C. liriodendri, C. macrodidymum and C. pauciseptatum on apple trees. Cylindrocarpon macrodidymum was the most prevalent. Isolates within each of the four species were pathogenic towards apple seedlings, but varied in their virulence. With a single exception, all isolates were able to induce lesion development on seedling roots. Only 57% of the isolates, which represented all four species, were able to cause a significant reduction in seedling weight and/or height. The greatest seedling growth reductions were caused by two isolates of C. destructans, and one isolate each of C. liriodendri and C. macrodidymum. A quantitative real-time polymerase chain reaction (qPCR) method was developed for simultaneous detection of all four Cylindrocarpon species. qPCR analyses of Cylindrocarpon from the roots of inoculated seedlings showed that the amount of Cylindrocarpon DNA in roots was not correlated to seedling growth reductions (weight and height) or root rot. The qPCR method is, however, very useful for the rapid identification of apple associated Cylindrocarpon species in roots. The technique may also hold potential for being indicative of Cylindrocarpon disease potential if rhizosphere soil rather than roots are used.
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Link to article at publishers website
Database assignments for author(s): Lizel Mostert, Mark Mazzola

Research topic(s) for pests/diseases/weeds:
surveys/sampling/distribution

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Ilyonectria destructans	Apple (Malus)	South Africa
	Dactylonectria macrodidyma	Apple (Malus)	South Africa
	Ilyonectria liriodendri	Apple (Malus)	South Africa
	Dactylonectria pauciseptata	Apple (Malus)	South Africa