Speciation genetics and genomics in a basidiomycete yeast

担子菌酵母的形态遗传学和基因组学

• 批准号: RGPIN-2015-05423
• 负责人: Xu, Jianping
• 金额: $ 2.48万
• 依托单位: McMaster University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2019
• 资助国家: 加拿大
• 起止时间: 2019-01-01 至 2020-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=685371
• 关键词: Speciation; genetics; genomics; basidiomycete; yeast

Fungi play pivotal roles in human health, agriculture, forestry, and the environment. Yet, relatively little is known about the factors involved in fungal population dynamics and speciation. Hybrid spore lethality is the hallmark of post-zygotic reproductive isolation and speciation in fungi. However, there is little information about the genetics of post-zygotic reproductive isolation in fungi. The human pathogenic yeast Cryptococcus neoformans has a bipolar mating system with two mating types, MATa and MATalpha and contains two divergent varieties var. neoformans and var. grubii. Hybrids between the two varieties produce basidiospores that have germination rates 80% in intra-varietal crosses. Here we propose to use microbiological, genetic and genomic approaches to investigate the factors contributing to the low hybrid spore viability in C. neoformans. The proposal has four specific aims:***AIM 1: Identify the chromosomal structural differences between strains JEC20 and CDC15. These two strains have been used as parents in our hybrid cross to study hybrid linkage mapping, transgressive segregation, mitochondrial inheritance, and meiotic and mitotic recombination. We have recently obtained the genome sequences of JEC20 and CDC15 to help identify chromosomal rearrangements between them that will be further confirmed individually using locus specific PCR. The distributions of these rearrangements among natural strains will be analyzed.***AIM 2: Assess the effects of environmental factors and individual chromosome rearrangements on hybrid spore viability. Specifically, we will test the effects of media, temperature, and incubation time on basidiospore germination rate and compare those from intra-varietal crosses with hybrid inter-varietal crosses. We will further micro-dissect and analyze ~5000 basidiospores from the JEC20 x CDC15 cross and genotype all germinated spores (estimated at ~900) at the confirmed rearranged chromosomal regions.***AIM 3: Identify the specific incompatibility gene regions involved in hybrid spore lethality through high-density linkage mapping. We will conduct high-density linkage mapping for gene regions containing candidate incompatibility loci identified recently and in AIM 2 using more progeny and more markers.***AIM 4: Test the roles of incompatibility genes through gene knockouts and replacements. We will use molecular biological tools to systematically knockout and replace the candidate incompatibility genes and determine their effects on cell viability and spore germination.******Our research will generate significant new information about the mechanisms controlling post-zygotic reproductive isolation in this important fungus. This research will greatly enhance our understanding of the distributions and dynamics of fungal species and genotypes in human hosts and in agriculture and forestry ecosystems.**

真菌在人类健康、农业、林业和环境中发挥着关键作用。然而，对真菌种群动态和物种形成所涉及的因素知之甚少。杂种孢子致死性是真菌合子后生殖隔离和物种形成的标志。然而，很少有关于真菌合子后生殖隔离的遗传学信息。人类致病性酵母隐球菌neoformans有一个双极交配系统，有两种交配类型，MATa和MATalpha，并包含两个不同的变种var。neoformans和var. grubii。两个品种之间的杂交产生的担孢子在品种内杂交中发芽率为80%。本文拟从微生物学、遗传学和基因组学的角度探讨导致C.新人类*** 目标1：确定菌株JEC20和CDC 15之间的染色体结构差异。这两个菌株已被用作亲本在我们的杂交研究杂种连锁图谱，超亲分离，线粒体遗传，减数分裂和有丝分裂重组。我们最近获得了JEC20和CDC 15的基因组序列，以帮助鉴定它们之间的染色体重排，这些重排将使用位点特异性PCR进一步单独确认。将分析这些重排在天然菌株中的分布。*目的2：评价环境因素和个体染色体重排对杂种孢子活力的影响。具体来说，我们将测试培养基、温度和孵育时间对担孢子萌发率的影响，并比较品种内杂交与品种间杂交的担孢子萌发率。我们将进一步显微解剖和分析来自JEC20 x CDC 15杂交的约5000个担孢子，并在确认的重排染色体区域对所有萌发的孢子（估计约900个）进行基因分型。目的3：通过高密度连锁图谱分析，确定与杂种孢子致死相关的特异性不亲和基因区域。我们将使用更多的后代和更多的标记，对最近和AIM 2中发现的含有候选不亲和位点的基因区域进行高密度连锁作图。*目的4：通过基因敲除和替换来检测不亲和基因的作用。我们将使用分子生物学工具系统地敲除和替换候选的不亲和基因，并确定它们对细胞活力和孢子萌发的影响。我们的研究将产生重要的新信息的机制控制合子后生殖隔离在这个重要的真菌。这项研究将大大提高我们对人类宿主和农业和林业生态系统中真菌物种和基因型的分布和动态的理解。