Please use this identifier to cite or link to this item: http://hdl.handle.net/11455/53567
標題: Xanthomonas 第三型制病性蛋白分子的致病分子機制探討
Functional Studies of Xanthomonas Type III Effector Proteins
作者: 楊俊逸
關鍵字: 生物技術;商品化;致病性蛋白分子;Xanthomonas;過敏性反應;光型態發育;吉貝素
摘要: 
第三型致病性蛋白分子是探討病原菌與植物交互作用的重點,但由於致病性蛋白分子具有功能性重疊以及結構模仿的特性,因此無法單純藉由突變菌株以及序列比對來分析或預測致病性蛋白分子的功能,所以大多數致病性蛋白分子的致病分子機制仍然未知。本計畫擬藉由轉基因植物的策略進行X. campestris pv. campestris第三型致病性蛋白分子的全面性深入探討,目前研究團隊在AvrXccC和XopD的研究上已有初步成果,發現AvrXccC引發細胞死亡的原因可能和AvrB完整蛋白區段的AMPylation活性有關,因此擬將利用遺傳突變,篩選AvrXccC誘發植物過敏性反應的因子。同時研究團隊發現XopD的轉殖株會形成胚軸延長、子葉向下彎曲和葉綠素缺失的白化苗,此外表型和光型態發育缺失以及吉貝素過度誘導有關。實驗證明XopD會和光訊息傳導的轉錄因子HFR1結合,因此擬將利用蛋白質體學分析,探討XopD如何干擾光與吉貝素的訊息傳導來抑制植物的免疫反應。雖然研究的對象為十字花科黑腐病菌X. campestris pv. campestris,但由於許多第三型致病性蛋白分子具有蛋白同源性,因此本計畫的研究成果將可應用在感染其他作物的Xanthomonas上,如柑桔的X. axonopodis pv. citri、茄科的X. campestris pv. veiscatoria以及水稻的X. oryzae pv. oryzae。期望藉由此創新前瞻性的研究計畫,提升台灣在研究植物細菌病害的領域與深度,並找尋有效控制細菌病害的策略。

The pathogenicity of Xanthomonas depends on the type III secretion system which injects effector proteins into host cells. These effectors interfere with host immunity responses and manipulate host cellular environment to benefit bacteria growth. However, with the aspects of functional redundancy of non-homologous type III effectors, mutations of individual effector genes rarely affect the virulence phenotype. Moreover, type III effectors have evolved a powerful strategy to manipulate host cellular functions by structural mimicry, which has no obvious amino-acid sequence similarity for functional annotation. As a result, the biochemical activities of most effectors are still unknown. In this proposal, transgenic Arabidopsis approach will be used to uncover the molecular mechanisms of virulence effectors of X. campestris pv. campestris. Now we have obtained preliminary results from AvrXccC and XopD studies. Our data shows that the ability of AvrXccC in triggering programmed cell death maybe dependent on the AMPylation activity of intact AvrB-like domain. Here, a modified mutagenesis strategy will be used to screen key factors involved in hypersensitive response elicited by AvrXccC. Our data also shows that the expression of XopD in planta can induce etiolated seedlings with elongated hypocotyls, epinastic and chlorosis cotyledons. This phenotype is correlated with repression of photomorphogenesis and induction of gibberillin signaling. In addition, we have demonstrated that XopD can interact with HFR1, a transcription factor involved in light signaling transduction pathway. Here, the proteomic strategy will be used to identify XopD interacting proteins in understanding how XopD inhibit plant immunity responses through light and gibberillin signaling regulation. Many X. campestris pv. campestris type III effectors have homologues in X. axonopodis pv. citri, X. campestris pv. vesicatoria and X. oryzae pv. oryzae. As a result, the studies on crucifer disease can be further used to control citrus, pepper, tomato and rice diseases.
URI: http://hdl.handle.net/11455/53567
其他識別: NSC100-2321-B005-007-MY3
Appears in Collections:生物化學研究所

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