COLLETOTRICHUM ACUTATUM ニ ヨル カプリチェリータンソビョウ ノ カンセンゲン ニ カンスル ケンキュウ

東京都世田谷区の東京農業大学世田谷キャンパス内の高層建築物とコンクリート塀に囲まれた中庭に,1978年種子によりエクアドルから導入されたカプリチェリー(Prunus capuli)が植栽されている。1997年このカプリチェリーにColletotrichum acutatumによる炭疽病の発生が確認された。同病の感染源に関して知見を得るため,その中庭に生育する種々の植物葉から分離される炭疽病菌について調査・検討を行った。これまで未記録の宿主植物を含む各種植物の展開葉からは,褐色斑点や褐変部の有無に関わらずC. acutatumが高頻度に分離され,分離菌株はその分離源植物の違いに関わらずほぼ共通の宿主範囲を有した。調査地内の各種植物間では共通の宿主を経由してC. acutatumが互いに感染・蔓延していることが強く示唆されるとともに,かなり以前からC. acutatumが国内に蔓延している可能性が考えられた。カプリチェリー炭疽病は病原菌の侵入経路が不明とされていたが,以上の結果からカプリチェリー導入前後に同菌に感染した植物がこの中庭に持ち込まれて周囲の植物に同菌が発生または潜在感染し,さらにそれらの感染植物体上のC. acutatumが同病の最初の感染源となった可能性が示された。A capulicherry (Prunus capuli) tree was introduced by seed in 1978 from Equador in the quadrangle surrounded by tall buildings and the fence in Setagatya campus of Tokyo University of Agriculture, Setagatya-ku, Tokyo and found to be infected with Colletotrichum acutatum whose origin was unknown. Pathogenicity of the anthracnose fungi isolated from various plants grown at the quadrangle were investigated to clarify the origin of the capulicherry anthracnose pathogen. C. acutatum was frequently isolated from the fully expanded leaves of many species of plant including new hosts with or without brown lesion and/or area. The isolates of C. acutatum had almost common host range in spite of their source plant species. These results and previous reports suggested that the plants grown in the quadrangle were infected with C. acutatum through common host plants and C. acutatum had been distributed in Japan at least before 1980. It seemed from consideration mentioned above that the origin of capulicherry anthracnose pathogen had been introduced with some other infected plants externally and /or latently that surrounded the tree before or after introduction of the tree

ERWINIA CAROTOVORA SUBSP. CAROTOVORAニ ヨル ホワイトレースフラワー ナンフビョウ シンショウ ノ ハッセイ ニ ツイテ

2001年10月,千葉県安房郡丸山町でホワイトレースフラワーの茎および葉柄が軟化腐敗し,悪臭を放つ病害の発生を認めた。本病罹病株から分離した細菌は,ホワイトレースフラワー苗を軟化腐敗させた。分離細菌は,グラム反応陰性,通性嫌気性,37℃で発育し,グルコースを発酵的に分解,硝酸塩を還元,ラクトースを利用し酸を産生したが,インドールを産生せず,酒石酸の利用は認めなかった。以上の結果から,本分離細菌をErwinia carotovora subsp. carotovoraと同定し,病名をホワイトレースフラワー軟腐病(英名 ; soft rot)とすることを提案する。On October in 2001, a new rotting disease was found on white lace flower (Ammi majus L.) in Chiba prefecture, Japan. The diseased plant primarily showed water-soaked brown spots on the stem, petioles and leaves near the soil. The diseased tissues were rotten with peculiar odor and the whole of the plant finally wilted. Bacteria isolated from rotten tissues and isolated bacteria produced rotten symptoms on the white lace flower, chinese cabbage and cucumber plants by artificial inoculation. The causal bacterium was identified as Erwinia carotovora subsp. carotovora (Jones) BERGEY et.al. 1923 according to its pathogenicity and bacteriological characteristics. Bacterial disease of white lace flower has not been recorded in Japan, therefore we proposed the name "soft rot" for this disease

PSEUDOMONAS CICHORII SWINGLE1925 STAPP1928ニ ヨル メボウキ コクハンサイキンビョウ シンショウ ニ ツイテ

2003年10月千葉県千倉町のビニルハウス栽培メボウキの葉,葉柄および茎に黒色水浸状斑および黒色条斑を形成し,ついには枯死する病害の発生を認めた。被害部からは細菌のみが分離され,分離菌はその病原性,細菌学的性質,血清学的性質からPseudomonas cichorii(Swingle1925)Stapp1928と同定された。P. cichoriiによるメボウキの病害は,わが国未報告であることから,病名を黒斑細菌病(英名 ; Bacterial black spot)とすることを提案した。In October, 2003, a new bacterial black spot disease was found on basil (Ocimum basilicum L.) in Chiba prefecture, Japan. This disease was characterized by the formation of irregular shaped brownish-black spots or streaks on the leaves, petioles and stems. Bacteria isolated from disease tissues produced black spots and streaks similar to natural infection on the basil by spray inoculation method. The causal bacterium was identified as Pseudomonas cichorii (Swingle 1925) Stapp1928 based on pathogenicity, bacteriological and serological characteristics. Bacterial disease of basil caused by P. cichorii has not been recorded in Japan. Therefore, we proposed the name "bacterial black spot" for this disease

モモセン コウサイキン ビョウキン(オモ ニXanthomonas arboricola pv. pruni)ノ ヤクザイ カンジュセイ ニ カンスル ケンキュウ

モモせん孔細菌病は重要病害の一つであり,国内ではXanthomonas arboricola pv. pruni, Pseudomonas syringae pv. syringae およびBrenneria nigrifluensの3種が病原細菌として報告されている。一般的に本病の主病原はX. a. pv. pruniであるとされているが,それを詳細に調査した報告は少ない。また,本病の防除は抗生物質剤を中心とした薬剤の散布が主である。抗生物質剤は様々な病害で薬剤耐性菌の発生が報告されており問題となっている。本病においても耐性菌の出現による防除効果の低下が懸念されている。そこで,2008年から2011年の4年間に合計7県151ほ場からモモせん孔細菌病罹病試料を採取し,病原細菌を分離,国内で発生している本病の主病原を再確認したところ,分離した菌株のほとんどがX. a. pv. pruniであったことから本病の主病原はX. a. pv. pruniである可能性が示唆された。さらに,菌株のオキシテトラサイクリン,オキソリニック酸およびストレプトマイシンに対する最小生育阻止濃度(MIC)を調査したところ,オキシテトラサイクリンおよびオキソリニック酸に対するMICは25ppm以下であった。一方,ストレプトマイシンに対してはMICが2000ppm以上を示す菌株が200菌株と全体の43%を占めており,ストレプトマイシンに対して耐性を有するX. a. pv. pruniが比較的高い割合で存在することが示唆された。Although bacterial shot hole disease is one of the most important diseases in peach production and three pathogens have been reported from the disease in Japan, there is little investigation on the dominant pathogen. As the use of bactericidal antibiotics is indispensable to control this disease, emergence of the causal bacteria with resistance to bactericides has been reported and is noticed as a serious problem in peach production. Samples of peach plants with bacterial shot hole disease were collected from 151 fields in 7 prefectures in four years from 2008 to 2011 for isolation and reaffirmation of the main causal bacteria. Most frequently isolated bacteria was identified as Xanthomonas arboricola pv. pruni, recognized as the dominant causal agent of bacterial shot hole disease of peach. The bacterial isolates identified as the dominant pathogen were examined for their minimal inhibitory concentration (MIC) against oxytetracycline, oxolinic acid and streptomycin to evaluate their susceptibility. Although all isolates tested were susceptible to oxytetracycline and oxolinic acid and showed <25ppm (MIC), 200 isolates (43% of tested isolates) showed more than 2000ppm (MIC) to streptomycin and were judged as resistant. The results of the survey showed the considerably higher population of X. a. pv. pruni with resistance to streptomycin in peach fields

Bmi1 Confers Resistance to Oxidative Stress on Hematopoietic Stem Cells

The polycomb-group (PcG) proteins function as general regulators of stem cells. We previously reported that retrovirus-mediated overexpression of Bmi1, a gene encoding a core component of polycomb repressive complex (PRC) 1, maintained self-renewing hematopoietic stem cells (HSCs) during long-term culture. However, the effects of overexpression of Bmi1 on HSCs in vivo remained to be precisely addressed.In this study, we generated a mouse line where Bmi1 can be conditionally overexpressed under the control of the endogenous Rosa26 promoter in a hematopoietic cell-specific fashion (Tie2-Cre;R26Stop(FL)Bmi1). Although overexpression of Bmi1 did not significantly affect steady state hematopoiesis, it promoted expansion of functional HSCs during ex vivo culture and efficiently protected HSCs against loss of self-renewal capacity during serial transplantation. Overexpression of Bmi1 had no effect on DNA damage response triggered by ionizing radiation. In contrast, Tie2-Cre;R26Stop(FL)Bmi1 HSCs under oxidative stress maintained a multipotent state and generally tolerated oxidative stress better than the control. Unexpectedly, overexpression of Bmi1 had no impact on the level of intracellular reactive oxygen species (ROS).Our findings demonstrate that overexpression of Bmi1 confers resistance to stresses, particularly oxidative stress, onto HSCs. This thereby enhances their regenerative capacity and suggests that Bmi1 is located downstream of ROS signaling and negatively regulated by it