Collaborative Research: Patterns and Mechanisms of Gene Expression in Recent Allopolyploids of Recurrent Origin

多倍体(基因组复制)是植物进化的主要力量，也是其他生物的重要进化过程，但基因组加倍的生态、生理、遗传和基因组后果大多尚不清楚。大多数多倍体是通过两个物种之间的杂交形成的，目前还不清楚多倍体是表达了双亲的所有属性，还是结合了双亲的一些特征的嵌合体。最近对多倍体基因表达的研究主要集中在人工产生的拟南芥、棉花和小麦中的多倍体，而不是自然产生的多倍体。此外，尽管大多数多倍体物种在自然界中重复形成，但这种反复形成对基因表达的影响尚不清楚。一个尚未解决的中心问题是，不同来源的个体是否表现出相似或不同的基因表达谱。Tragopogon(菊科，向日葵科)提供了一个研究自然种群现代和轮回多倍体的模式系统。两个新的多倍体物种(T.mirus和T.miscellus)是在20世纪初从欧洲引进三个二倍体物种(T.dubius、T.pratensis和T.porrifolius)到北美西部后形成的。Tragopogon miscellus是特别有趣的，因为它也是相互形成的(即一次以T.dubius为母本，多次以T.pratensis为母本)。这个项目将涉及分子和基因组方法，以解决一系列问题，这些问题是增加对多倍体的理解的基础。例如，在这些新近形成的多倍体中是否存在新的基因表达？基因表达模式在独立起源的多倍体种群中是否有所不同？基因表达是否受到母方和父方贡献的影响？F1杂种和新产生的多倍体的基因表达模式是否与自然产生的多倍体的基因表达模式不同？什么类型的基因在天然多倍体中经历了差异表达，什么类型的机制导致了观察到的基因表达差异？这些问题在目前的作物系统中或用重新合成的多倍体都不容易解决。这项研究将首次对自然多倍体种群中的基因表达进行严格的评估，并对两个新的多倍体物种的快速进化成功提供新的见解。PIS D.Soltis、P.Soltis、J.Tate(佛罗里达大学)和Z.J.Chen(德克萨斯农工大学)之间的合作结合了他们各自在进化生物学和分子遗传学方面的专业知识。培训本科生和研究生、博士后和K-12教师的机会被纳入该项目。

Polyploidy (genome duplication) represents a major force in plant evolution and an important evolutionary process in other organisms, but the ecological, physiological, genetic, and genomic consequences of genome doubling remain mostly unknown. Most polyploids are formed via hybridization between two species, and it is unclear whether the polyploids express all of the attributes of both parents or are mosaics that combine some characters of each parent. Recent studies of polyploid gene expression have focused on artificially produced polyploids in Arabidopsis, cotton, and wheat rather than on naturally occurring polyploids. In addition, although most polyploid species have formed repeatedly in nature, nothing is known about the consequences of this recurrent formation on gene expression. A central question yet to be addressed is whether individuals of separate origin show similar or divergent gene expression profiles. A model system for the study of recent and recurrent polyploidy in natural populations is provided by Tragopogon (Asteraceae, the Sunflower family). Two new polyploid species (T. mirus and T. miscellus) were formed following the introduction of three diploid species (T. dubius, T. pratensis, and T. porrifolius) from Europe to western North America during the early 1900s. Tragopogon miscellus is particularly interesting because it has also formed reciprocally (that is, once with T. dubius as the maternal parent and multiple times with T. pratensis as the maternal parent). This project will involve molecular and genomic approaches to address a series of questions that are fundamental to an increased understanding of polyploidy. For example, does novel gene expression occur in these recently formed polyploids? Do gene expression patterns differ among polyploid populations of independent origin? Is gene expression affected by maternal and paternal contributions? Do gene expression patterns in F1 hybrids and newly produced polyploids differ from those of the naturally occurring polyploids? What types of genes undergo differential expression in the natural polyploids, and what types of mechanisms lead to the observed differences in gene expression? Such questions cannot be readily addressed in current crop systems or with resynthesized polyploids. This research will provide the first rigorous assessment of gene expression in natural polyploid populations, plus new insights into the rapid evolutionary success of two new polyploid species. The collaboration among PIs D. Soltis, P. Soltis, J. Tate (University of Florida) and Z. J. Chen (Texas A&M University) combines their respective expertise in evolutionary biology and molecular genetics. Opportunities for training of undergraduate and graduate students, post-docs, and K-12 teachers are integrated into the project.