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Mowlick S.,Yamagata University | Yasukawa H.,Nara Prefectural Agricultural Experiment Station | Inoue T.,Yamaguchi Prefectural Technology Center for Agriculture and Forestry | Takehara T.,Japan National Agriculture and Food Research Organization | And 3 more authors.
Crop Protection | Year: 2013

Biological soil disinfestation (BSD) is a method of controlling soil-borne pests and diseases through anaerobic decomposition of plant biomass incorporated in field soil with temporary irrigation and covering with sheets. In this study, effects of BSD on suppression of spinach wilt disease were investigated in two different field experiments using mainly Brassica juncea plants as plant biomass. Soil bacterial community compositions were analyzed with clone library analysis based on 16S rRNA gene sequences to determine the relationship between the bacterial composition in the treated soil and suppression of the disease. For the BSD-treated soils, oxidation-reduction potential dropped, and acetate was usually detected at high concentrations. Although the control treatment (irrigation and polythene covering without biomass) decreased the wilt disease incidence in spinach plants cultivated in the treated plot as compared with those for the non-treated plot, BSD-treatments suppressed the disease more effectively. The clone library results showed that both non-treated and control soils contained diversified bacterial communities of various phylogenetic groups, while members of the Firmicutes mainly from the class Clostridia dominated in the BSD-treated soils. The clostridial groups detected were diverse and the major clone groups were closely related to strictly anaerobic fermentative bacteria such as Clostridium saccharobutylicum, Clostridium cylindrosporum, Clostridium sufflavum, and Clostridium xylanovorans. These clostridial groups were almost eliminated from the soil bacterial community when the BSD-treated soil was treated again with irrigation and covering without biomass before the next cropping, in which the wilt disease was hardly suppressed. © 2013. Source


Mowlick S.,Yamagata University | Inoue T.,Yamaguchi Prefectural Technology Center for Agriculture and Forestry | Takehara T.,Japan National Agriculture and Food Research Organization | Kaku N.,Yamagata University | And 2 more authors.
AMB Express | Year: 2013

Soil bacterial composition, as influenced by biological soil disinfestation (BSD) associated with biomass incorporation was investigated to observe the effects of the treatment on the changes and recovery of the microbial community in a commercial greenhouse setting. Chloropicrin (CP) was also used for soil disinfestation to compare with the effects of BSD. The fusarium wilt disease incidence of spinach cultivated in the BSD- and CP-treated plots was reduced as compared with that in the untreated control plots, showing effectiveness of both methods to suppress the disease. The clone library analyses based on 16S rRNA gene sequences showed that members of the Firmicutes became dominant in the soil bacterial community after the BSD-treatment. Clone groups related to the species in the class Clostridia, such as Clostridium saccharobutylicum, Clostridium tetanomorphum, Clostridium cylindrosporum, Oxobacter pfennigii, etc., as well as Bacillus niacini in the class Bacilli were recognized as the most dominant members in the community. For the CP-treated soil, clones affiliated with the Bacilli related to acid-tolerant or thermophilic bacteria such as Tuberibacillus calidus, Sporolactobacillus laevolacticus, Pullulanibacillus naganoensis, Alicyclobacillus pomorum, etc. were detected as the major groups. The clone library analysis for the soil samples collected after spinach cultivation revealed that most of bacterial groups present in the original soil belonging to the phyla Proteobacteria, Acidobacteria, Bacteroidetes, Gemmatimonadetes, Planctomycetes, TM7, etc. were recovered in the BSD-treated soil. For the CP-treated soil, the recovery of the bacterial groups belonging to the above phyla was also noted, but some major clone groups recognized in the original soil did not recover fully. © 2013 Mowlick et al.; licensee Springer. Source


Mowlick S.,Yamagata University | Inoue T.,Yamaguchi Prefectural Technology Center for Agriculture and Forestry | Takehara T.,Japan National Agriculture and Food Research Organization | Tonouchi A.,Hirosaki University | And 3 more authors.
Crop Protection | Year: 2014

Biological soil disinfestation (BSD) is an effective method to suppress soilborne plant diseases by incorporation of plant biomass into soil under reduced, anoxic condition. Usefulness of Japanese-radish (daikon) residue as plant biomass for BSD was investigated by both model and field experiments in comparison with the effects of Brassica juncea plants or wheat bran. Considerable amounts of acetate together with minor amounts of propionate and butyrate were detected from the radish-treated soils at similar levels with those in soils treated with B.juncea plants or wheat bran. BSD treatments with radish residue reduced spinach wilt disease incidence in both model and field experiments. When the BSD-treated soil was treated again with irrigation and covering without biomass before next cropping, however, wilt disease was hardly suppressed. Clone library analysis based on 16S rRNA gene sequences was carried out to determine the changes in the bacterial community compositions in the treated soil samples. The analyses showed that the bacterial communities in the radish-treated soils were dominated by members of the classes Clostridia and Bacilli of the phylum Firmicutes in both experiments. The clostridial groups detected were diverse and the major operational taxonomic units (OTUs) were closely related to Clostridium saccharobutylicum, Clostridium sufflavum, Clostridium xylanovorans, and Oxobacter pfennigii, which had been commonly detected as the dominant groups in BSD-soils treated with B.juncea plants or wheat bran in our previous studies. The dominant clone groups belonging to the Bacilli class were closely related to several species such as Bacillus niacini, Bacillus circulans, and Bacillus pycnus. Dominancy of the Bacilli groups seemed to increase when radish residue was repeatedly applied as BSD material. © 2014 Elsevier Ltd. Source


Fujii K.,Yamaguchi Prefectural Technology Center for Agriculture and Forestry | Ohmido N.,Kobe University
Theoretical and Applied Genetics | Year: 2011

Resynthesized Brassica napus cv. Hanakkori (AACC, 2n = 38) was produced by cross-hybridization between B. rapa (AA, 2n = 20) and B. oleracea (CC, 2n = 18) as a new vegetative crop. Many studies have provided evidences for the instability and close relationship between A and C genome in the resynthesized B. napus cultivars. In fact, seed produced to obtain progeny in Hanakkori had unstable morphological characters and generated many off-type plants. In this study, we investigated the pollen fertility, chromosome number, structure, and behavior linked to various Hanakkori phenotypes to define factors of unstable phenotypic expression in the progeny. Hanakkori phenotypes were categorized into five types. The results of pollen fertility, chromosome number, and fluorescence in situ hybridization analysis for somatic mitosis cells indicated that the off-type plants had lower pollen fertility, aberrant chromosome number, and structures with small chromosome fragments. Observation of chromosomes at meiosis showed that the meiotic division in off-type plants led to appreciably higher abnormalities than in on-type plants. However, polyvalent chromosomes were observed frequently in both on- and off-type plants in diplotene stage of meiosis. We assume that the unstable morphological characters in resynthesized progeny were the result of abnormal division in meiosis. It results as important that the plants of normal phenotype, chromosome structure and minimized abnormal meiosis are selected to stabilize progeny. © 2011 Springer-Verlag. Source


Nguyen M.T.,Hanoi University of Agriculture | Nguyen M.T.,Tottori University | Nguyen M.T.,Yamaguchi University | Akiyoshi K.,Yamaguchi Prefectural Technology Center for Agriculture and Forestry | And 3 more authors.
Soil Science and Plant Nutrition | Year: 2010

This study analyzed the phenotypic and genotypic characters of nodulating rhizobia isolated from two soybean cultivars, Kyushu 151 and Sachiyutaka, in the same field of the Yamaguchi Prefectural Technology Center of Agriculture and Forestry in Japan. The isolates were classified into groups using phenotypic characteristics, such as growth rate, color change on Bromothymol blue-containing yeast extract-mannitol agar (YMA) plates and colony morphology on YMA plates, and by genotypic characteristics, such as polymerase chain reaction-restriction fragment length polymorphism patterns of the 16S ribosomal RNA genes (16S rDNA) and the internal transcribed sequence (ITS) regions. In Kyushu 151, single phenotypic and genotypic groups were isolated from every nodule examined. In Sachiyutaka, plural strains belonging to distinct groups were obtained frequently from single nodules, indicating that multiple occupancy was established at high frequency. No fixed combination of the groups was found in the composition of multiple occupancy. An increase in the relative abundance of isolates belonging to Sinorhizobium fredii (Ensifer fredii) occurred concomitantly with the increase in the proportion of nodules with multiple occupancy. Nearly 60% of the isolates from Sachiyutaka belonged to S. fredii; 75% of them were obtained from nodules with multiple occupancy. © 2010 Japanese Society of Soil Science and Plant Nutrition. Source

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