Cylindrocarpon species associated with apple tree roots in South Africa and their quantification using real-time PCR

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.

Cylindrocarpon root rot: multi-gene analysis reveals novel species within the Ilyonectria radicicola species complex

“…Cylindrocarpon and Cylindrocarpon-like species have since been commonly associated with root and decay of woody and herbaceous plants (Domsch et al 2007). Cylindrocarpon root rot causes losses up to 30% on ginseng (Panax quinquefolium) (Seifert et al 2003), and plays an important role in black foot rot of grapevines (Halleen et al 2004(Halleen et al , 2006, apple replant disease (Tewoldemedhin et al 2010), and beech cankers (Castlebury et al 2006), to name but a few hosts of economic importance.…”

Genetic diversity in Dactylonectria pauciseptata associated with black foot disease in New Zealand

“…To date, it has been characterised by morphology, DNA sequencing and pathogenicity assays as a pathogen of grapevine and other hosts in many countries, including Spain, Turkey, Canada, Brazil, and Italy (Martin et al 2011;Erper et al 2013;Úrbez-Torres et al 2014;dos Santos et al 2014;Aiello et al 2014 In other countries, researchers have studied the pathogenicity of D. pauciseptata isolates recovered from woody plants of grapevines and other hosts. In South Africa, four species ("C. " destructans, I. liriodendri, D. macrodidyma, D. pauciseptata) recovered from apple roots were able to induce lesion development on seedling roots with variable pathogenicity, except for one isolate of D. pauciseptata (STE-U6630), which did not cause a significant amount of root rot or reduction of weight and height (Tewoldemedhin et al 2011). In Turkey, Erper et al (2013) tested the pathogenicity of selected isolates from a group identified as Dactylonectria and Ilyonectria species, including a D. pauciseptata isolate from kiwifruit.…”

Association of Neonectria macrodidyma with Dry Root Rot of Citrus in California

“…It is also important in apple [7], pine and other conifer seedlings, and the forest nurseries [8,9]. Neonectria macrodidyma is a necrotic plant pathogen and a new name was recently proposed as Dactylonectria macrodidyma (syn.…”