氏 名 | ナシール カイルン ヒサム ビン MASIR Khairun Hisam Bin |
本籍(国籍) | マレーシア |
学位の種類 | 博士 (農学) | 学位記番号 | 連研 第334号 |
学位授与年月日 | 平成17年9月30日 | 学位授与の要件 | 学位規則第4条第1項該当 課程博士 |
研究科及び専攻 | 連合農学研究科 生物資源科学専攻 | ||
学位論文題目 | Functional screening of plant cell death-inducing factors ( 植物細胞死誘導因子の機能的スクリーニング ) |
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論文の内容の要旨 | |||
We performed high-throughput screening using potato virus X(PVX) system to overexpress Nicotiana benthamiana genes in planta and identify positive regulators of cell death. This screening identified NbCD1, a novel class Ⅱ ethlene responsive element binding factor(ERF), as a potent inducer of the hypersensitive response(HR)-like cell death. NbCD1 expression was induced by treatments with INF1 elicitor and a non-host pathogen Pseudomonas cichorii. NbCD1 exhibited transcriptional repressor activity through its EAR motif, and this motif was necessary for NbCD1 to cause cell death. We identified 58 genes that display altered transcription following NbCD1 overexpression. NbCD1 overexpression down-regulated the expression of HSR203, a negative regulator of hypersensitive death. Conditional expression of NbCD1 in Arabidopsis also caused cell death, indicating that NbCD1 downstream cascades are conserved in dicot plants. To further confirm the role of NbCD1 in defense, we used virus-induced gene silencing to demonstrate that NbCD1 is required for nonhost resistance of N.benthamiana to the bacterial pathogen P. cichorii. Our data points to a model of transcriptional regulatory cascades. NbCD1 positively regulates cell death and contributes to nonhost resistance, possibly by down-regulating the expression of other defense response genes. By the same screening, we also identified NbCD3 gene coding for a novel MAPKK. Details of NbCD3 are also descussed. (日本語訳) |