Department of Biology, University of Massachusetts, Amherst, MA 01003, USA.
Mol Ecol. 2011 Sep;20(18):3743-56. doi: 10.1111/j.1365-294X.2011.05216.x. Epub 2011 Aug 19.
Growth-related traits, such as greater height, greater biomass, faster growth rate and early flowering, are thought to enhance competitiveness of agricultural weeds. However, weedy rice, a conspecific weed of cultivated rice (Oryza sativa L.), displays variation for growth traits. In the United States, separately evolved weedy rice groups have been shown to share genomic identity with exotic domesticated cultivars. Through a common garden experiment, we investigated whether growth trait divergence has occurred among U.S. weeds and their putative cultivated progenitors. We also determined polymorphism patterns in the growth candidate gene, SD1, to assess its possible role in the evolution of divergent phenotypes. We found considerable growth trait variation among weed groups, suggesting that growth trait convergence is not evident among weedy populations. Phenotypic divergence of weedy rice from cultivated ancestors is most apparent for flowering time. Introgression of a chromosomal block containing the SD1 allele from tropical japonica, the predominant U.S. rice cultivar, was detected in one weedy rice population and is associated with a change in growth patterns in this group. This study demonstrates the role of introgressive hybridization in evolutionary divergence of an important weed.
生长相关特性，如更高的高度、更大的生物量、更快的生长速度和更早的开花，被认为可以提高农业杂草的竞争力。然而，作为栽培稻（Oryza sativa L.）的同种杂草，野败表现出了生长特性的变异。在美国，已证明分别进化的野败群体与外来驯化品种具有相同的基因组身份。通过一个田间试验，我们研究了美国杂草及其可能的栽培祖先之间是否发生了生长特性的分歧。我们还确定了生长候选基因 SD1 的多态性模式，以评估其在表型分歧进化中的可能作用。我们发现杂草群体之间存在相当大的生长特性变异，这表明在野败群体中，生长特性的趋同并不明显。野败稻与栽培祖先的表型分歧在开花时间上最为明显。在一个野败稻群体中检测到了来自热带粳稻（美国主要的水稻品种）的含有 SD1 等位基因的染色体片段的渗入，这与该群体中生长模式的变化有关。这项研究表明，渐渗杂交在重要杂草的进化分歧中起着重要作用。
