Introgression in Helianthus (Asteraceae)

小行星9419206 生物物种通常被定义为种群中不与其他群体交换基因的杂交生物群体。 任何阻碍两个物种之间基因交换的因素都有助于生殖隔离，从而有助于个体物种的完整性和一致性。 然而，物种之间的许多生理或生殖障碍并不能完全阻止基因流动，而是允许少量的杂交发生;其中一些障碍实际上可能将基因流动限制在基因组的某些区域。 印第安纳州大学的Loren Rieseberg博士的研究目的是通过经验测试植物基因流动的最重要生殖障碍之一--染色体结构差异的影响。 这将通过调查从向日葵属（菊科）向日葵物种的两个杂交群体（在加州和俄克拉荷马州）获得的数百株个体植物，并通过利用作为先前研究支持的结果已经开发的向日葵染色体的139个特定基因组标记来实现。 因为这些分子标记的染色体位置在每个亲本向日葵物种中是已知的，并且在几种情况下位置不同，所以它们可以用于追踪特定基因或染色体片段在两个杂交区中跨越物种屏障的流动。 这些结果将产生有关染色体结构差异作为生殖障碍的有效性的数据，并将表明这种障碍是否仅将种间基因流限制在基因组结构相似的区域。

9419206 Rieseberg Biological species are often defined as groups of interbreeding organisms in populations that do not exchange genes with other groups. Any factor that impedes the exchange of genes between two species contributes to reproductive isolation and hence to the integrity and coherence of individual species. However, many physiological or reproductive barriers between species do not prevent gene flow completely but allow some small amount of hybridization to occur; and some of these barriers may actually limit gene flow to certain regions of the genome only. The purpose of research by Dr. Loren Rieseberg at Indiana University is to test empirically the effects of one of the most important reproductive barriers to gene flow in plants, chromosomal structural differences. This will be accomplished by surveying several hundred individual plants taken from two hybridizing populations (in California and Oklahoma) of sunflower species, genus Helianthus (Asteraceae), and by making use of 139 particular genomic markers of sunflower chromosomes already developed as a result of prior research support. Because the chromosome locations of these molecular markers are known in each of the parental sunflower species and differ in location in several instances, they can be used to trace the flow of particular genes or chromosomal segments across the species barrier in the two zones of hybridization. The results will yield data about the effectiveness of chromosomal structural differences as reproductive barriers and they will indicate whether such barriers limit interspecific gene flow to structurally similar regions of the genome only.