Sahashi N.,Japan Forestry and Forest Products Research Institute |
Akiba M.,Japan Forestry and Forest Products Research Institute |
Ishihara M.,Hokkaido Research Center |
Ota Y.,Laboratory of Microbial Ecology |
Kanzaki N.,Japan Forestry and Forest Products Research Institute
Forest Pathology | Year: 2012
The fungus Phellinus noxius has a broad host range and causes brown root rot in a variety of tree species of various ages, irrespective of their original health. The fungus is widely distributed in tropical countries of Southeast Asia, the Pacific Islands and Australia, Central America and Caribbean, and Africa. Since 1988, when brown root rot was first found on Ishigaki Island, Okinawa Prefecture, the disease has been reported on several islands in Okinawa and Kagoshima Prefectures, and it has been causing serious problems to shade, windbreak, ornamental and landscape trees in the Ryukyu Islands, located in the subtropical region of southern Japan. Here, we report on the current status of P. noxius-caused brown root rot in the Ryukyu Islands, Japan, including symptoms, occurrence, dispersal, distribution and host tree species of the disease, pathogenicity and/or virulence of the pathogen, and disease management based on our surveys and previously published reports from Japan. Brown root rot has been confirmed in 53 tree species from 32 plant families at different sites on 10 of the 12 islands surveyed. Among the 53 tree species, 34 were first recorded in Japan as host plants of P. noxius. The disease occurs mainly in shade, ornamental and windbreak trees at sightseeing places, parks, roadsides, agricultural land such as sugar cane fields, and around residences or other places associated with human activities. © 2012 Blackwell Verlag GmbH.
Morrissey E.M.,Virginia Commonwealth University |
Jenkins A.S.,Virginia Commonwealth University |
Brown B.L.,Virginia Commonwealth University |
Franklin R.B.,Laboratory of Microbial Ecology
Wetlands | Year: 2013
Microbial communities in freshwater wetland soils process nitrate via denitrification (DNF) and dissimilatory nitrate reduction to ammonium (DNRA). Because the processes generate different end products (N-gas versus NH 4 +), the relative dominance of DNF versus DNRA has implications for ecosystem nitrogen cycling, greenhouse gas production, and downstream eutrophication. To examine how resource availability affects these two microbial groups, wetland soil was supplemented with labile (compost) or recalcitrant (wood) organic matter (OM) and/or potassium nitrate fertilizer. Following a three-month in situ incubation, the abundance and composition of the DNF- and DNRA-capable microbes were examined via quantitative polymerase chain reaction (qPCR) and terminal restriction fragment length polymorphism (T-RFLP) using process-specific functional genes (DNF: nirS qPCR, nosZ T-RFLP; DNRA: nrfA qPCR and T-RFLP). Denitrifer abundance was positively related to OM lability and simultaneous nitrate amendment enhanced OM effects, while DNRA abundance varied little across treatments. For both groups, community structure showed an interactive response to OM type and nitrate availability, even when abundances did not change. This work highlights the importance of considering co-varying resource gradients, and the differential responses of DNF and DNRA communities to resource manipulation provides insight into the environmental regulators of ecosystem nitrate removal in wetlands. © US Government 2013.