ORIGINAL ARTICLE 1 H NMR and GC-MS metabolic fingerprinting of developmental stages of Rhizoctonia solani sclerotia K. A. Aliferis Æ S. Jabaji Received: 3 April 2009 / Accepted: 1 September 2009 / Published online: 17 September 2009 Ó Springer Science+Business Media, LLC 2009 Abstract Rhizoctonia solani AG-3 is a soilborne plant pathogen that forms resting vegetative structures called sclerotia. These compact structures are crucial to the path- ogen’s survival and pathogenesis. The metabolic changes occurring during sclerotia development were monitored using proton nuclear magnetic resonance ( 1 H NMR) spec- troscopy and gas chromatography–mass spectrometry (GC- MS). The validation, discrimination, and the establishment of correlative relationships between metabolite signals were performed by principal component analysis (PCA) and partial least squares-discriminant analysis (PLS-DA). The results of the analyses suggested that out of the 116 com- pounds that were simultaneously analyzed and compared using GC-MS, a-a-trehalose, D-glucose, 9-(Z)-octadecenoic and 9,12-octadecadienoic acids, xylitol, and glucitol were key metabolites that were highly dependent on the devel- opmental stage of the sclerotia contributing to their dis- crimination and classification. Furthermore, the application of 1 H NMR and GC-MS metabolic fingerprinting on the same biological sample provided complementary informa- tion illustrating the value of this integrated approach in the study of metabolic changes in fungal structures. Keywords Biomarkers Á Metabolites Á Metabolomics Á Plant pathogen Á Black scurf Á Potato 1 Introduction The fungus Rhizoctonia solani Ku ¨hn complex is a taxo- nomic entity composed of morphologically similar groups that share similar characteristics, multinucleate cells, pro- duction of sclerotia, and lack of conidia (Parmeter and Whitney 1970). The identification of R. solani isolates is based on the ability of their hyphae to anastomose (Carling 1996), and currently, there are 13 known anastomosis groups (AGs) of R. solani (Carling et al. 2002). Rhizoctonia disease of potato, caused by AG-3 isolates of R. solani is considered one of the most important fungal disease in potato fields and in certified seed production world-wide (Carling et al. 1989). The disease is characterized by the presence of cankers on the sprouts, stems and stolons and the formation of black sclerotia (black scurf) on the surface of potato tubers (Banville et al. 1996). Sclerotia of R. solani are compact bodies of aggregated melanized hyphae that help the path- ogen to survive under unfavourable conditions for long periods due to their high resistance to chemical and bio- logical degradation (Sumner 1996). Their formation and differentiation is triggered by oxidative stress or their thiol redox state (Georgiou and Petropoulou 2001; Patsoukis and Georgiou 2007). Tuber-borne sclerotia are considered the most important source of inoculum for the next season, especially if potatoes are grown continuously (Sumner 1996). Complete eradica- tion of tuber-borne sclerotia has never been achieved, while various control measures, including integrated control has reduced the incidence of the disease but not completely eradicated it (Jager et al. 1991; Secor and Gudmestad 1999; Van den Boogert and Luttikholt 2004). Comprehensive studies focusing on the physiology and chemical composi- tion of R. solani sclerotia would provide useful information that could be exploited in the implementation of effective Electronic supplementary material The online version of this article (doi:10.1007/s11306-009-0180-4) contains supplementary material, which is available to authorized users. K. A. Aliferis Á S. Jabaji (&) Department of Plant Science, McGill University, 21111 Lakeshore Road, Sainte-Anne-de-Bellevue, QC H9X 3V9, Canada e-mail: suha.jabaji@mcgill.ca 123 Metabolomics (2010) 6:96–108 DOI 10.1007/s11306-009-0180-4