Ribosomal DNA Systematics of Ceratobasidium and Thanatephorus with Rhizoctonia anamorphs

Vascular Streak Dieback of cacao in Southeast Asia and Melanesia: in planta detection of the pathogen and a new taxonomy

“…Consistent with the observation of Gonzalez et al (2001) that Ceratobasidium is more diverse than Thanatephorus our results show a paraphyletic Ceratobasidium and a monophyletic Thanatephorus. Oncobasidium theobromae does not cluster with Thanatephorus, but it is closely allied to Ceratobasidium AG 0 s A, Bo, and K, leading us to conclude that Ot is a unique species of Ceratobasidium.…”

“…However, isolates of Ceratobasidium did not form a monophyletic group suggesting that the genus is paraphyletic. This result was consistent with the study of Gonzalez et al (2001) where Ceratobasidium was not resolved as monophyletic based on ITS and LSU sequence data. The four pure cultures of Ot (SULAWESI 8, 10, 11, and 12) isolated in this study were identical to sequences deposited for Ot from Malaysia and Java.…”

“…Therefore, he synonymized Oncobasidium with Thanatephorus, and transferred Oncobasidium theobromae to that genus. Results from Gonzalez et al (2001) and here suggest that Ceratobasidium is paraphyletic and Thanatephoprus is monophyletic. Our phylogenetic analysis of two ribosomal genes gives moderate support for the derivation of O. theobromae from within Ceratobasidium and that at least for now the appropriate genus for this fungus is Ceratobasidium.…”

“…Oncobasidium theobromae does not cluster with Thanatephorus, but it is closely allied to Ceratobasidium AG 0 s A, Bo, and K, leading us to conclude that Ot is a unique species of Ceratobasidium. This is further supported by the presence of binucleate hyphal cells (Talbot & Keane 1971;Roberts 1999), a characteristic that defines Ceratobasidium (Gonzalez et al 2001 For descriptions of this species see Talbot & Keane (1971) and Roberts (1999, as Thanatephorus).…”

“…Moreover, in the absence of pure cultures O. theobromae has not been included in any phylogenetic analyses of the Ceratobasidiales (e.g. Gonzalez et al 2001Gonzalez et al , 2006 and its systematic position is unknown. No cultures are known to have been derived from basidiospores of O. theobromae.…”