Ophiognomonia Castanea’s Biological Characteristics,Life Cycle And Relationship With Phomopsis Mollissima

Phomopsis mollissima is a new disease recent years of Castanea mollissima production areas in Shandong province, its pathogen is Phomopsis castaneae-mollissima. In the study of P.mollissima found a fungi of Ophiognomonia on lesion is also parasitic, which was named Ophiognomonia castanea here. This article studied O. castanea Systematic.1.The identification of O. castaneaAnamorph of O.castanea is acervulus,98.75μm diamx32.4μm high; conidiophores are colorless, linearis, without diaphragm; conidia is colorless, linear, single-cell, straight or slightly curved, without diaphragm,9.7μm long x1.94μm diam. Teleomorph of O.castanea is perithecia, on leaf blades and veins, solitary, glossy black, globose to subglobose,144.47μm diamx148.68μm high; necks central, mostly straight, sometimes curved,246.69μm high x23.27μm diam; asci fusiform to ellipsoid, apical ring conspicuous, ascospores arranged multiseriate,26.58μm longx5.17μm diam; ascospores fusiform with rounded ends, slightly curved, one-septate, median to indistinctly supramedian, slightly constricted at septum, each cell with one large and one small guttule,12.19μm longx1.55μm diam. O.castanea colonies is yellow or brown, thick, and have a gray-brown back. Irregularly shaped colonies, colonies mostly easy to produce polysaccharide secretions, and colony morphology is diverse. Mycelium extract DNA, internal transcribed spacer (ITS1and ITS2),5.8S and partial18S and28S regions were amplified using primers ITS1/ITS4, phylogenetic tree, to support it as a new species.2.The biological characteristics of O.castanea myceliumThe results show that the most suitable carbon source to O.castanea mycelium is mannitoi, the second is maltose; it is more adapted to use organic nitrogen sources, like peptone, the second is beef extract; Hyphae heat temperature of35℃, low temperature to5℃can not grow, the optimum temperature is25℃; pH4-9in PDA medium hyphae could grow, the optimum pH is6; and the optimal medium is potato-chestnut leaf culture medium.3.Preliminary studies on the life history of O.castaneaPreliminary studies on the life history of O.castanea show, in late September, O.castanea began to form Anamorph-acervulus on the lesion of dorsal. On March5-6next year there grows the teleomorph of O.castanea-perithecia in the same position. Spores and mycelia can overwinter, ascospores be the primary infection, no re-infection. Induction the fruiting bodies of O.castanea. The teleomorph induced of O.castanea test results show that the humidity is the key factors that affecting the formation of perithecia, and lighting is of little effect. Anamorph inducted of O.castanea test results showed that cultured easily induced at ambient conditions, same conidia spores produced with nature.4.The relationship between O.castanea and P.castaneae-mollissimaThe separation frequency and proportion of O.castanea and P.castaneae-mollissima changes show P.castaneae-mollissima first infected leaves, Produce disease spot, late in the onset O.castanea infected leaves, P.castaneae-mollissima separation frequency slightly decreases, O.castanea frequency separation rapidly increasing and eventually exceed P.castaneae-mollissima. The teleomorph and anamorph of O.castanea grows in Pmollissima disease spot. O.castanea and P.castaneae-mollissima pathogenicity test results show P.castaneae-mollissima virulent and lesion produce fast, O.castanea have weak pathogenicity, virulence mixed inoculation is more than individually inoculated P.castaneae-mollissima, exhibit complex infection characteristics.3strains of O.castanea with P.castaneae-mollissima is vegetative affinity.