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.

丝状子囊菌产生的无性孢子称为分生孢子。子囊菌是最大的真菌类群，包含大多数农作物和人类真菌病原体。分生孢子是这些生物体的主要生殖细胞和传播剂，但也可以在有性生殖过程中充当雄性受精剂。我们发现模型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）参与形成复杂细胞的分生孢子吻合管通过细胞融合形成网络，以及（c）最近发现的分生孢子性管，它参与与异性细胞的有性融合。分生孢子性管的产生机制，特别是它们如何受到性信息素和光的调节，是本提案研究的重点。一个有趣的方面是分生孢子性管形成在最接近光源的一侧（即它们表现出正向光性）。我们研究计划的第一个目标是分析信息素信号传导的作用。特别是，我们将确定合成性信息素是否可以诱导分生孢子性管形成。我们发现分生孢子性管是响应红光而形成的，这涉及两种称为光敏色素的红光感光器。我们的第二个目标是分析这些光敏色素受体如何响应红光，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，结果显示其拥有约 10,000 个基因。脉孢菌的大约 10,000 个基因中的每一个都会发生突变，产生“敲除突变体”。我们的第三个目标是筛选数百个这样的敲除突变体，以确定它们在分生孢子性管形成和/或向光性方面是否存在缺陷。我们还获得了证据表明另外两种光感受器参与分生孢子性管的形成：一种称为隐花色素的蓝光光感受器，以及一种属于视蛋白家族的绿光光感受器（其中还包括在分生孢子中发现的光感受器视紫红质）。人眼）。这些光感受器在真菌中的作用目前尚不清楚。我们的第四个目标是分析隐花色素和两种不同视蛋白在分生孢子性管形成及其可能的向光性生长中的作用。第五个目标将涉及通过用荧光标记来标记光敏色素、隐花色素和视蛋白光感受器，从而使它们能够用荧光显微镜在活细胞中成像。通过这种方式，我们将能够直接监测它们是否因光照而改变其亚细胞位置。我们的最终目标是确定不同的光感受器是否相互作用并响应光信号而一致行动，从而导致分生孢子性管的形成和向光性。