Phytochrome and pheromone signalling during the induction of a new cell type involved in sexual fusion in filamentous fungi

丝状真菌有性融合过程中诱导新细胞类型过程中的光敏色素和信息素信号传导

• 批准号: BB/F013574/1
• 负责人: Nick Read
• 金额: $ 62.04万
• 依托单位: University of Edinburgh
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2008
• 资助国家: 英国
• 起止时间: 2008 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=BB%2FF013574%2F1
• 关键词: Phytochrome; pheromone; signalling; during; induction

The asexual spore produced by filamentous ascomycete fungi is called a conidium. The ascomycetes are the largest group of fungi and contain the majority of crop and human fungal pathogens. Conidia are the main reproductive cells and dispersal agents of these organisms, but can also act as male fertilizing agents during sexual reproduction. We have discovered that conidia of the model ascomycete fungus, Neurospora crassa, can produce three types of filamentous cells: (a) the conidial germ tube which is involved in colony establishment, (b) the conidial anastomosis tube which is involved in forming complex cellular networks by undergoing cell fusion, and (c) the most recently discovered conidial sex tube which is involved in sexual fusion with cells of the opposite sex. The mechanism by which conidial sex tubes are produced, and particularly how they are regulated by sex pheromones and by light, is the focus of the research in the present proposal. One interesting aspect is that the conidial sex tubes are formed on the side closest to the light source (i.e. they exhibit a positive phototropism). The first objective of our research proposal will be to analyse the role of pheromone signalling. In particular, we will determine whether a synthetic sex pheromone can induce conidial sex tubes to form. We have found that conidial sex tubes are formed in response to red light and this involves two red light photoreceptors called phytochromes. Our second objective will be to analyse how these phytochrome receptors respond to red light, and in doing so, regulate the formation of conidial sex tubes. Neurospora crassa was the first filamentous fungus to have its genome completely sequenced and as a result has been shown to possess ~ 10,000 genes. Each of Neurospora's ~ 10,000 genes is being mutated to produce 'knockout mutants. Our third objective will be to screen several hundred of these knockout mutants to determine if they are defective in conidial sex tube formation and/or phototropism. We have also obtained evidence that two other photoreceptors are involved in the formation of conidial sex tubes: a blue light photoreceptor called cryptochrome, and a green light photoreceptor belonging to the opsin family of proteins (which also includes the photoreceptor rhodopsin which is found in the human eye). The roles of these photoreceptors in fungi are currently unknown. Our fourth objective will be to analyse the roles of cryptochrome and two different opsins in the formation of conidial sex tubes and possibly their phototropic growth. The fifth objective will involve visualizing the phytochrome, cryptochrome and opsin photoreceptors by tagging them with fluorescent labels which allow them to be imaged in living cells with a fluorescence microscope. In this way we will be able to directly monitor whether they change their subcellular location in response to light exposure. Our final objective will be to be to determine if the different photoreceptors interact and act in concert in response to the light signals that result in the formation and phototropism of conidial sex tubes.

由丝状子囊菌产生的无性孢子称为分生孢子。子囊菌是真菌中最大的类群，含有大多数作物和人类真菌病原体。分生孢子是这些生物的主要生殖细胞和传播媒介，但在有性生殖过程中也可作为雄性传播媒介。我们发现模式子囊菌真菌粗糙脉孢菌的分生孢子可以产生三种类型的丝状细胞：（a）参与菌落建立的分生孢子芽管，（B）分生孢子吻合管，通过细胞融合参与形成复杂的细胞网络，以及（c）最近发现的分生孢子性管，参与与异性细胞的性融合。分生孢子性管产生的机制，特别是它们如何受到性信息素和光的调节，是本建议研究的重点。一个有趣的方面是分生孢子性管形成在最靠近光源的一侧（即它们表现出正向光性）。我们的研究计划的第一个目标将是分析信息素信号的作用。特别是，我们将确定是否合成性信息素可以诱导分生孢子性管的形成。我们已经发现分生孢子性管的形成是对红光的反应，这涉及到两种被称为光敏色素的红光光感受器。我们的第二个目标将是分析这些光敏色素受体如何对红光做出反应，并在此过程中调节分生孢子性管的形成。粗糙脉孢菌是第一个对其基因组进行完全测序的丝状真菌，因此已被证明拥有约10，000个基因。脉孢菌的约10，000个基因中的每一个都被突变以产生“敲除突变体”。我们的第三个目标将是筛选几百个这些敲除突变体，以确定它们是否有缺陷的分生孢子性管形成和/或向光性。我们还获得了另外两种光感受器参与分生孢子性管形成的证据：一种被称为隐花色素的蓝光感受器和一种属于视蛋白家族的绿色光感受器（其中还包括在人眼中发现的光感受器视紫红质）。这些光感受器在真菌中的作用目前尚不清楚。我们的第四个目标将是分析隐花色素和两种不同的视蛋白在分生孢子性管的形成和可能的向光生长中的作用。第五个目标将涉及可视化光敏色素，隐花色素和视蛋白光感受器，通过标记它们的荧光标记，使它们能够在活细胞中用荧光显微镜成像。通过这种方式，我们将能够直接监测它们是否改变其亚细胞位置以响应光暴露。我们的最终目标将是确定不同的光感受器是否相互作用，并采取一致行动，以响应导致分生孢子性管的形成和向光性的光信号。