探討玉米黑穗病中PR-1La依賴的阿魏酸訊息傳導路徑;Investigating the PR-1La-Dependent FA-Sensing Signaling Pathway in Ustilago maydis

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Title:	探討玉米黑穗病中PR-1La依賴的阿魏酸訊息傳導路徑;Investigating the PR-1La-Dependent FA-Sensing Signaling Pathway in Ustilago maydis
Authors:	張䎙之;Chang, Pin-Chih
Contributors:	生命科學系
Keywords:	玉米黑穗病;G 蛋白媒介訊息傳導路徑;假性菌絲;酚類化合物;類PR蛋白;Ustilago maydis;G protein-mediated signaling pathway;G protein-coupled receptor;pseudohyphae formation;phenolic compound;PR1-like
Date:	2024-10-04
Issue Date:	2025-04-09 16:09:15 (UTC+8)
Publisher:	國立中央大學
Abstract:	雙型性絲狀真菌是一類能夠感知環境訊號並從營養型轉變為絲狀菌絲型態的微生物。這種形態轉換使它們能夠啟動感染過程,並在宿主植物體內完成整個生命週期。絲狀型態的產生需要一系列後續訊息路徑的激活,包括環境感知、特定基因的表達上調,以及複雜的調控網路的參與。在先前的研究發現,生物營養型真菌玉米黑穗病菌 (Ustilago maydis) 能夠感知宿主植物中的酚類化合物,並通過其細胞壁效應蛋白UmPR-1La來誘導絲狀生長。被UmPR-1La保護的絲狀菌絲能夠有效抵抗植物酚類化合物的毒性,提高其生存能力。但是,依賴於UmPR-1La感知酚類化合物的具體信號傳導通路仍不清楚。本研究表明,玉米黑穗病菌通過G蛋白信號通路感知訊號,以UmPR-1La依賴的方式觸發菌絲的形成。剔除GPA3會導致細胞形態明顯變化,維持絲狀生長;相反地,當GPA3活性型態被持續表達時,細胞對酚類化合物保持不敏感,保持芽胞形態。另一方面,在酚類化合物處理下，剔除GPA1不會誘導絲狀生長。這表明, GPA1在UmPR-1La依賴的絲狀生長中起正向作用，與GPA3的負向作用不同。而GPA2和GPA4在剔除後不具有顯著的影響。通過比較轉錄組分析,我發現G蛋白信號通路、MAPK信號通路以及一些效應蛋白和轉錄因子的表達都發生了上調，在參與配對、費洛蒙感知、絲狀菌絲生長和毒力上扮演UmPR-1La依賴和不依賴的角色。除此之外，也發現到費洛蒙基因MFA 的正向誘導受到UmPR-1La的存在所影響，然而，費洛蒙接收與訊息傳遞和UmPR-1La所產生的菌絲之間的關係仍需要日後的研究，在本篇論文，我主要發現型態轉換受環境訊號影響並受配對機制的過程所交互作用共同產生的結果，使真菌可以生長及成功佔領寄主。;Dimorphic filamentous fungi are capable to respond to environmental cues, transitioning from vegetative to filamentous cells. This transition enables them to initiate the infection process and complete life cycle within hosts. The initiation of filamentous growth requires the activation of subsequent events, including environmental sensing, upregulation of specific genes, and involvement of regulatory networks. We have previously demonstrated that the biotrophic fungus U. maydis responds to plant phenolics by inducing filamentous growth through a cell wall-associated effector protein, UmPR-1La. The UmPR-1La-shielded filaments effectively counteract the toxicity of plant phenolics and enhance survival. However, the specific signaling pathway dependent on the perception of phenolics by UmPR-1La remains unexplored. Here, I demonstrate that U. maydis perceives signals through the G-protein signaling pathway to trigger the filament formation in an UmPR-1La-dependent manner. The deletion of GPA3 resulted in cells exhibiting distinct morphology and remaining in filamentous form. In contrast, when the active form of Gpa3 was constitutively expressed, cells were insensitive to the phenolic treatment and retained sporidial morphology. On the other hand, the deletion of GPA1 did not induce filamentation, and the cells stayed as yeast-like cells. My findings suggest that, compared to the negative role of Gpa3, Gpa1 positively regulates U. maydis filamentous growth in an UmPR-1La-dependent manner, whereas Gpa2 and Gpa4 are dispensable in this signaling pathway. Through comparative transcriptomics analysis, I identified the upregulation of components in the G-protein signaling pathway (including Gpa2 and GPCR proteins) and the MAPK signaling pathway. Additionally, I also observed the upregulation of effector proteins and transcription factors that are known to regulate the events of mating/pheromone sensing and filamentous growth/virulence, both in UmPR-1La-dependent and independent manners. Indeed, the upregulation of pheromone gene MFA was also dependent on the presence of UmPR-1La. However, how pheromone sensing and host-signal perception are integrated to trigger the UmPR-1La-dependent filamentous growth is currently unknown and awaits investigation. My findings highlight the complexity of morphological transitions, demonstrating that these processes integrate both host environmental cues and the mating process. This underscores the intricate interplay between external signals and internal cellular mechanisms required for fungal development and successful adaptation in plant hosts.
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