酵母属间杂合子在选择压力下的基因组结构演变

Interspecies hybridization, the efficient strategy to obtain the hybrid combining the advantages of both parents, has been widely applied in microorganism genetic breeding. However, the key factors for determining two parent genomic incompatibility and compatibility, and the course of genome rebuilding under environmental selection, remain unresolved. It is not only the essential issue of biology, but also the theoretical foundation for genetic breeding. Kluyveromyces marxianus (KM), the yeast in Kluyveromyces genus in Saccharomycetaceae, grows very fast, resists high temperature, and can utilize xylose. Saccharomyces cerevisiae (SC), the yeast in Saccharomyces genus in Saccharomycetaceae, has high ethanol tolerance, and large ethanol production. In this project, we will introduce KM and SC to perform cross-genus hybridization, and carry out the successive propagation under different driving conditions until the stable karyotype is achieved. Via.analyzing the phenotype and karyotype characteristics for the heterozygotes in different generations, as well as the genomic structure (including recombination, Indel or SNP) for the heterozygotes in the 0 generation, semi-stable generation, and stable generation, we focus on investigating the evolution of genomic structure for KM/SC heterozygote under different selection stresses, and the accompanied phenotypic variation, to elucidate environment stress’s effect on the course of KM-SC genome compatibility and stabilization in heterozygote, and to construct the correlation model for environment stress – phenotype character – genomic structure. Our work not only enriches the knowledge of interspecific hybrid evolution under selection pressure, but also may obtain a more desirable strain with industrial properties, to prepare the upgrading for ethanol production strains.

跨物种杂交，获得兼具两亲本优势的杂合子，被广泛应用于微生物遗传育种。两亲本基因组的不相容及相容的决定因素、适应环境选择时基因组的重塑过程，是生物学的基本问题和遗传育种的理论依据，但一直悬而未决。马克斯克鲁维酵母(KM)位于酵母科克鲁维属，生长快、耐高温、可利用木糖；酿酒酵母(SC)位于酵母科酵母属，乙醇耐受性高、产率高。本项目用KM和SC进行跨属杂交，在不同驱动条件下连续传代直至核型稳定。通过分析不同代数杂合子的表型特征，以及0代、半稳定代、稳定代杂合子的基因组结构（包括核型、缺失、插入、倍增、重组、SNP），研究KM/SC杂合子在不同选择压力下基因组结构的演变过程，及伴随的表型变化，揭示环境压力对KM和SC基因相容至稳定的影响，建立环境压力/表型特征/基因组结构的关联模型。本研究成果将丰富人们对选择压力下物种进化过程的认识，有望获得更具工业价值的菌株，为乙醇生产菌的更新换代提供储备。

跨物种杂交，获得兼具两亲本优势的杂合子，被广泛应用于微生物遗传育种。两亲本基因组的不相容及相容的决定因素、适应环境选择时基因组的重塑过程，是生物学的基本问题和遗传育种的理论依据，但一直悬而未决。马克斯克鲁维酵母(KM)位于酵母科克鲁维属，生长快、耐高温、可利用木糖；酿酒酵母(SC)位于酵母科酵母属，乙醇耐受性高、产率高，在工业蛋白/疫苗等领域中具有重要应用前景。本项目开展了马克斯克鲁维酵母菌株的高密度细胞生长及其在工业蛋白中应用的研究；也进行了马克斯克鲁维酵母属间杂合和在不同压力驱动条件下进行马克斯克鲁维酵母的实验室适应性进化的研究；建立核型演变和生理表型变化的关联模型，揭示基因组结构的演变过程；建立了马克斯克鲁维酵母多倍体构建与检测技术等研究方法。采用染色体工程的方法，将马克斯克鲁维酵母染色体遗传的关键元件着丝粒CEN和自主复制系列ARS，用基因编辑技术整合到酿酒酵母一条染色体上，并将这条染色体成功转入马克斯克鲁维酵母。本研究成果为马克斯克鲁维酵母工业育种提供了新的方法，获得更具工业价值的菌株，为工业乙醇发酵、重组蛋白生产的提供新的优良菌株。