疫病菌誘導蛋白elicitins之研究現況

Role of Elicitins in the Biology of Phytophtora

劉瑞芬(R.F Liou)

《植物病理學會刊》 10卷3期 (2001/09) Pp. 97-104

https://doi.org/10.6649/PPB.200109_10(3).0001

摘要

Elicitins 是在疫病菌(Phytophtora)及腐霉菌(Pythium)所發現的誘導蛋白，根據蛋白質結構及類緣分析結果，可將其區分為三群，大多數目前已被發現之elicitins屬於第一群，特主要包括：（一）分子量大約為１０kDa，一般含９８個胺基酸，且胺基酸序列在不同菌種間有相當程度之保守性，（二）對煙草引發過敏性反應，及（三）能夠誘導煙草產生系統性抗病反應。在煙草引發過敏反應與系統性誘導抗病時，elicitin所啟動庂訊息傳導機制與其他病原微生物所援用者有相似之處，但elicitin與煙草之交互作用顯然比其他系統還要複雜。此外，近來之研究現elicitin具有固醇載體活性，由於Phytophtora與Pythium均不具有合成固醇之能力，其是否利用elicitin自植物細胞膜獲取固醇以供生長與繁殖之需，仍待深入探討，固醇載體活性是否為elicitin展現誘導活性之必要條件也待進一步釐清。

關鍵字

疫病菌 ； 誘導蛋白 ； 過敏性反應 ； 系統性誘導抗病 ； 腐霉菌

並列摘要

Elicitins re structurally related proteins produced by species of Phytophthora and pythium (oomycetes). Based on the overall structure of the proteins as well as the phylogenetic analysis, elicitins may be divided into three classes. Class I encompasses most of the elicitins proteins identified thus far, with polypeptides of 98 amino acid residues and able to induce hypersensitive response as well as systemic acquired resistance in tobacco. Members of class II include elicitin sequences from P. cryptogea or P. cinnamomi, which encode hyperacidic elicitin proteins with extra short hydrophilic C-terminal tails. Class III contains two elicitin-like proteins, INF2A and INF2B of P. infestans, which encode the conserved 98amino acid elicitin signature, followed by a C-terminal domain of about 70 amino acid residues. However, it is not clear whether INF2 can elicit defense response in plants similar to the class I elicitins. In addition to their role as elicitors of plant defense response, elicitins also exhibited a sterol-binding activity. Therefore, it might act as shuttles trapping the sterols from the host plants. This property opens new perspectives concerning the role of elicitins in plant-Phytophthora interactions.

並列關鍵字

elicitin ； hypersensitive response ； Phytophthora ； Pythium ； systemic acquired resistance