The fungus Tricholoma matsutake forms an ectomycorrhizal relationship with pine trees. Its sporocarps often develop in a circle, which is commonly known as a fairy ring. The fungus produces a solid, compact, white aggregate of mycelia and mycorrhizae beneath the fairy ring, which in Japanese is called a 'shiro'. In the present study, we used soil dilution plating and molecular techniques to analyze the bacterial communities within, beneath, and outside the T. matsutake fairy ring. Soil dilution plating confirmed previous reports that bacteria and actinomycetes are seldom present in the soil of the active mycorrhizal zone of the T. matsutake shiro. In addition, the results showed that the absence of bacteria was strongly correlated with the presence of T. matsutake mycorrhizae. The results demonstrate that bacteria, especially aerobic and heterotrophic forms, and actinomycetes, are strongly inhibited by T. matsutake. Indeed, neither bacteria nor actinomycetes were detected in 11.3% of 213 soil samples from the entire shiro area by culture-dependent methods. However, molecular techniques demonstrated that some bacteria, such as individual genera of Sphingomonas and Acidobacterium, were present in the active mycorrhizal zone, even though they were not detected in soil assays using the dilution plating technique.

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Abstract. Maulidia V, Soesanto L, Syamsuddin, Khairan K, Hamaguchi T, Hasegawa K, Sriwati R. 2020. Secondary metabolites produced by endophytic bacteria against the Root-Knot Nematode (Meloidogyne sp.). Biodiversitas 21: 5270-5275. Endophytic bacteria live and colonize in plant tissues without causing disease to their plant host. Among several processes, these bacteria can produce secondary metabolites that can help in the defense of plant host against pathogens. This study aimed to identify endophytic bacteria as biocontrol agents against Meloidogyne sp. in tomato plants. Six endophytic bacteria candidates from the genus Pseudomonas, Arthrobacter, Bacillus, and Serratia were isolated from Solanum Lycopersicum, Psidium guajava, Pinus merkusii, Dendrocalamus asper, Albizia chinensis, and Theobroma cacao L, respectively. The average mortality of Meloidogyne sp. by endophytic bacteria was 70,27% to 95,46%. From these, B. thuringiensis AK08 produced compounds of the secondary metabolites such as flavonoid, phenol, tannins, terpenoids, steroids, saponins, and alkaloids. The best result of the average incubation period, number of galls in the root, number of nematodes at the root, and the number of nematodes in the soil on tomato plant were shown by B. thuringiensis. The major compounds in GC-MS analysis of B. thuringiensis were cholest-5-en-3-ol (3.beta.)-carbonochloridate (25.35%). Bacillus thuringiensis not only has rules as bio-insecticide but also has nematicidal effect.

The seasonal changes in the number of free-living nematodes and the pinewood nematode (PWN), Bursaphelenchus xylophilus, in 15-year-old Japanese black pine (Pinus thunbergii) trees killed by the PWN were determined. Fifteen species of nematodes were isolated, i.e. one species, each of Mononchida and Plectidae, two species, each of Monhisterida, Rhabditida and Tylenchida, three species of Bursaphelenchus including the PWN, and four species of Diplogasterida. The PWN and one species of Diplogasterida were the most prevalent nematodes isolated. The numbers of PWNs decreased from August to December, 2004, but then increased in February, 2005, then decreased again until June, 2005. During the experimental period the population changes of the Diplogasterida nematode mimicked those of the PWN, however, correlations between the numbers of the two nematodes varied considerably both among trees and seasons. Both the PWN and the Diplogasterida nematode were more abundant around the pupal chambers of the vector beetle, Monochamus alternatus, than elsewhere in the tree wood. Jpn. J. Nematol. 36 (2), 87-100 (2006).