Department of Horticulture, Oregon State University, ALS 4017, Corvallis, OR 97331, USA.
Mol Phylogenet Evol. 2013 Jan;66(1):17-29. doi: 10.1016/j.ympev.2012.08.026. Epub 2012 Sep 14.
The cultivated strawberry is one of the youngest domesticated plants, developed in France in the 1700s from chance hybridization between two western hemisphere octoploid species. However, little is known about the evolution of the species that gave rise to this important fruit crop. Phylogenetic analysis of chloroplast genome sequences of 21 Fragaria species and subspecies resolves the western North American diploid F. vesca subsp. bracteata as sister to the clade of octoploid/decaploid species. No extant tetraploids or hexaploids are directly involved in the maternal ancestry of the octoploids. There is strong geographic segregation of chloroplast haplotypes in subsp. bracteata, and the gynodioecious Pacific Coast populations are implicated as both the maternal lineage and the source of male-sterility in the octoploid strawberries. Analysis of sexual system evolution in Fragaria provides evidence that the loss of male and female function can follow polyploidization, but does not seem to be associated with loss of self-incompatibility following genome doubling. Character-state mapping provided insight into sexual system evolution and its association with loss of self-incompatibility and genome doubling/merger. Fragaria attained its circumboreal and amphitropical distribution within the past one to four million years and the rise of the octoploid clade is dated at 0.372-2.05 million years ago.
栽培草莓是最年轻的驯化植物之一，于 18 世纪在法国由两个西半球八倍体物种的偶然杂交培育而成。然而，对于产生这种重要水果作物的物种的进化却知之甚少。对 21 个草莓种和亚种的叶绿体基因组序列的系统发育分析将北美西部的二倍体 F. vesca subsp. bracteata 解析为八倍体/十倍体物种的姐妹群。现存的四倍体或六倍体植物都没有直接参与八倍体的母系祖先。在 subsp. bracteata 中，叶绿体单倍型存在强烈的地理隔离，雌雄异株的太平洋沿岸种群不仅是八倍体草莓的母系谱系，也是雄性不育的来源。对草莓属植物有性系统进化的分析提供了证据，表明雄性和雌性功能的丧失可以在多倍体化后发生，但似乎与基因组加倍后自交不亲和的丧失无关。性状状态映射提供了对有性系统进化及其与自交不亲和和基因组加倍/融合丧失的关系的深入了解。草莓属在过去的 100 万到 400 万年中获得了其环绕北极和亚热带的分布，而八倍体进化枝的出现则可以追溯到 372 万到 205 万年前。
