, 2009). However, B. spartinae and three Harpophora isolates and two isolates of H. oryzae are clustered with very low bootstrap value support (<50%) (Fig. 1). Harpophora spp. with Gaeumannomyces teleomorphs are well known as
causes of take-all diseases of wheat and grasses (Freeman & Ward, 2004). Although H. oryzae is a close relative of Gaeumannomyces, an in vitro pathogenicity test shows that H. oryzae acts as a nonpathogenic endophyte colonizing cultivated rice (Oryza sativa L.) roots. Intracellular hyphae are found in the root cortex. After 30 days of coculture in half-strength Murashige and Skoog (1/2 MS) medium under aseptic conditions (25 °C, 18 h light/6 h darkness), H. oryzae strongly promotes growth and biomass formation of rice plants (see Supporting Information, Figs S1 and S2), similar Selleckchem Verteporfin to H. graminicola, a beneficial DSE of grasses (Kirk & Deacon, 1987; Newsham, 1999). In previous reports, isolates of the naturally occurring nonpathogenic G. cylindrosporus were effective in controlling talk-all when introduced into wheat crops (Gutteridge et al., 2007). Fungi living as endophytes in wild learn more rice have not yet been reported. During our search in 2007 and 2008, we recovered two Phialophora-like fungal
isolates from 354 samples in healthy roots, indicating a very low isolation rate. The present paper introduces H. oryzae as one of probably many other endophytes in this important crop plant. Based on the morphological characteristics, we place our novel isolates in Harpophora. We were unable to observe a teleomorph of these two isolates; also, keeping the two cultures for
3 weeks on oatmeal agar under light did not lead to fruiting body formation. To our knowledge, no Harpophora spp. has so far been found to be associated with cultivated rice plants (Fisher & Petrini, 1992; Tian et al., 2004; Naik et al., 2009; Vallino et al., 2009), but one recovered isolate was Palbociclib identified as P. verrucosa (Naik et al., 2009). Three Harpophora isolates recovered from wheat and barley in Germany and the United Kingdom (Ward & Bateman, 1999; Ulrich et al., 2000) (accession numbers: AJ132541, AJ132542 and AJ010039) formed a sister subclade to H. oryzae. It is possible that these are also H. oryzae or an allopatric species to it. Unfortunately, the three strains were not available for this study, and thus this question could not be answered. Hence, we have examined only the morphological description of the currently identified Harpophora spp. Harpophora oryzae is shown to be morphologically similar to H. zeicola, a maize root parasite (Deacon & Scott, 1983), and H. graminicola. It differed from H. zeicola in having massive aggregations of falcate conidia and densely branched conidiophores. Harpophora zeicola produced two types of conidia, one of which resembled those of H. oryzae; in H. oryzae, phialides are almost straight, while they are often curved in H. zeicola. The major differentiation from H. graminicola is in the conidial morphology.