Zhang Yunwei, Zalapa Juan E, Jakubowski Andrew R, Price David L, Acharya Ananta, Wei Yanling, Brummer E Charles, Kaeppler Shawn M, Casler Michael D
Grassland Institute, China Agricultural University, Beijing, China.
Genetica. 2011 Jul;139(7):933-48. doi: 10.1007/s10709-011-9597-6. Epub 2011 Jul 23.
Switchgrass (Panicum virgatum), a central and Eastern USA native, is highly valued as a component in tallgrass prairie and savanna restoration and conservation projects and a potential bioenergy feedstock. The purpose of this study was to identify regional diversity, gene pools, and centers-of-diversity of switchgrass to gain an understanding of its post-glacial evolution and to identify both the geographic range and potential overlap between functional gene pools. We sampled a total of 384 genotypes from 49 accessions that included the three main taxonomic groups of switchgrass (lowland 4x, upland 4x, and upland 8x) along with one accession possessing an intermediate phenotype. We identified primary centers of diversity for switchgrass in the eastern and western Gulf Coast regions. Migration, drift, and selection have led to adaptive radiation in switchgrass, creating regional gene pools within each of the main taxa. We estimate that both upland-lowland divergence and 4x-to-8x polyploidization within switchgrass began approximately 1.5-1 M ybp and that subsequent ice age cycles have resulted in gene flow between ecotype lineages and between ploidy levels. Gene flow has resulted in "hot spots" of genetic diversity in the southeastern USA and along the Atlantic Seaboard.
柳枝稷（Panicum virgatum）原产于美国中部和东部，作为高草草原和稀树草原恢复与保护项目的一个组成部分以及一种潜在的生物能源原料，具有很高的价值。本研究的目的是确定柳枝稷的区域多样性、基因库和多样性中心，以了解其冰期后的进化情况，并确定功能基因库之间的地理范围和潜在重叠。我们从49份种质中总共采样了384个基因型，这些种质包括柳枝稷的三个主要分类群（低地四倍体、高地四倍体和高地八倍体）以及一份具有中间表型的种质。我们确定了柳枝稷在墨西哥湾沿岸东部和西部区域的主要多样性中心。迁移、漂变和选择导致了柳枝稷的适应性辐射，在每个主要分类群中形成了区域基因库。我们估计，柳枝稷内的高地-低地分化和四倍体到八倍体的多倍体化大约始于150万至100万年前，随后的冰期循环导致了生态型谱系之间以及倍性水平之间的基因流动。基因流动在美国东南部和大西洋沿岸形成了遗传多样性的“热点”。
