Genotypic and Phenotypic Analyses of Hybridization in a Basidiomycete Yeast

杂交在自然界中普遍存在，例如，估计有25%的植物和10%的动物被认为是杂交起源的。然而，杂交和杂交表现的模式和遗传基础仍然知之甚少。这项研究的长期目标是了解杂交如何影响真菌种群动态和进化。短-短目标是使用人类致病隐球菌种复合体(CSC)作为模型来调查自然界中的杂交频率(目标1)；实验室杂交的表型多样性(目标2)；杂交活力的分子基础(目标3)；以及杂交的稳定性(目标4)和可育性(目标5)。CSC至少含有7个不同的单倍体谱系。然而，已经发现了天然的杂交种，并且可以在CSC创造实验室杂交种。目的1：目前已鉴定的CSC杂交种主要基于细胞表面特征，仅区分四种血清型，且遗传基础未知。目标1将使用歧视性遗传标记和基因组工具来筛选我们实验室的&gt；800全球CSC菌株。我们的数据将有力地识别天然的CSC杂交种，包括它们的潜在来源。目的2：杂交种的表型与亲本有何不同？亲本菌株之间的遗传差异是否与杂交后代的表型多样性呈正相关？在这里，我们将杂交来自不同CSC谱系的单倍体菌株，并在选定的条件下分析杂交后代的基因型和表型。目标3：杂交优势的遗传基础是什么？环境因素对表现出杂交活力的后代和没有杂交优势的后代的转录组有什么不同的影响？我们将分析具有代表性和极端表型的选定杂交种的基因组和转录本。目标4：混合动力车有多稳定？来自进化更远的血统的杂交后代是否更有可能在遗传上不稳定？在杂交后代中，某些染色体是否比其他染色体更不稳定？我们将使用实验进化来研究选定的杂交后代在数千代有丝分裂中的遗传和表型稳定性。目标5：杂交种彼此之间和/或与亲本品系的干扰程度如何？与亲本菌株间不育，但相互干扰，与立即杂交物种形成相一致。CSC杂交种的育性模式将与它们的基因类型进行比较，以帮助揭示杂交物种形成的遗传基础。我们提出的研究将产生关于CSC杂交模式、机制和后果的重要新信息，有助于对真菌种群动态和进化的新理解，并有助于培训加拿大的下一代微生物学家、遗传学家和传染病研究人员。

Hybridization is pervasive in nature, e.g. an estimated 25% of plants and 10% of animals are believed to be of hybrid origins. However, the patterns and genetic bases of hybridization and hybrid performance remain poorly understood. The long-term goal of this research is to understand how hybridization impact fungal population dynamics and evolution. The short-short objectives are to use the human pathogenic Cryptococcus species complex (CSC) as a model to investigate the frequencies of hybridization in nature (Aim 1); the phenotypic diversity of laboratory hybrids (Aim 2); the molecular bases for hybrid vigor (Aim 3); and the stability (Aim 4) and fertility of hybrids (Aim 5). CSC contains at least seven divergent haploid lineages. However, natural hybrids have been found, and laboratory hybrids can be created in CSC. AIM 1: The current CSC hybrids have been identified primarily based on a cell surface feature that only distinguishes four serotypes, and with an unknown genetic basis. Aim 1 will use discriminatory genetic markers and genomic tools to screen the >800 global CSC strains in our lab. Our data will robustly identify natural CSC hybrids, including their potential origins. AIM 2: How do the phenotypes of hybrids differ from parental strains? Is genetic divergence between parental strains positively correlated to phenotypic diversity among hybrid progeny? Here we will cross haploid strains from different CSC lineages and analyze both the genotypes and phenotypes of hybrids under select conditions. AIM 3: What are the genetic bases of hybrid vigor? How do environmental factors impact the transcriptome differently for progeny showing hybrid vigor and those that do not? We will analyze the genomes and transcriptomes of selected hybrids showing representative and extreme phenotypes. AIM 4: How stable are hybrids? Are hybrids derived from evolutionary more distant lineages more likely to be genetically unstable? Are certain chromosomes more unstable than others in hybrids? We will use experimental evolution to investigate the genetic and phenotypic stabilities of selected hybrids over thousands of mitotic generations. AIM 5: How interfertile are hybrids with each other and/or with parental strains? Inter-sterile with parental strains while interfertile with each other would be consistent with immediate hybrid speciation. The fertility pattern of CSC hybrids will be compared with their genotypes to help reveal the genetic bases for hybrid speciation. Our proposed research will generate significant new information about the patterns, mechanisms, and consequences of hybridization in CSC, contributing to novel understanding of fungal population dynamics and evolution and to training the next generation of microbiologists, geneticists, and infectious disease researchers in Canada.