Abstract

Gossypium, the cotton genus, includes ∼50 species distributed in tropical and sub-tropical regions of all continents except Europe. Here we provide a synopsis of the evolutionary history of Gossypium and domestication of the American allopolyploid species, integrating data from fundamental taxonomic investigations, biogeography, molecular genetics, phylogenetic analysis, and archaeology. These diverse sources of information provide a temporal and phylogenetic perspective on diversification among the diploids and on polyploid formation, uncover multiple previously cryptic interspecific hybridizations, clarify and contribute to the taxonomy of the genus, and offer a firm foundation for understanding parallel domestications in Mesoamerica and South America, which led to the globally important cotton crop species G. barbadense and G. hirsutum. Gossypium thus offers a testimonial example of the importance and utility of fundamental botanical discovery combined with modern technological capabilities to generate genomic insights into evolutionary history. We also review the current state of our knowledge regarding the archaeological history of cotton domestication and diffusion in the Americas, a seemingly unlikely story entailing parallel domestication origins and parallel directional selection tracing to 8,000 (G. barbadense) and 5,500 (G. hirsutum) years ago, transforming two geographically isolated wild short-day perennial shrubs having small capsules and seeds covered by short, tan-colored epidermal trichomes into modern daylength-neutral annuals bearing abundant, fine, strong white fibers. This dual domestication was followed several millennia later by unintentional and more recently intentional interspecific introgression, as the two species came into contact following their initial domestication in different hemispheres. Thus, the cycle of species divergence and biological reunion was reiterated, this time at the allopolyploid level. Understanding this evolutionary history is vitally important to our understanding of the genomic architecture of the world’s most important fiber plant and contributes substantially to our understanding of general biological principles.

摘要

棉花属棉属植物，约有 50 种，分布于除欧洲以外所有大陆的热带和亚热带地区。在这里，我们提供了棉属植物进化史的概要美洲异源多倍体物种的驯化，整合来自基础分类学调查、生物地理学、分子遗传学、系统发育分析和考古学的数据。这些不同的信息来源提供了关于二倍体之间的多样化和多倍体形成的时间和系统发育观点，揭示了多个以前神秘的种间杂交，澄清并有助于该属的分类学，并为理解中美洲和美洲的平行驯化提供了坚实的基础。南美洲导致了全球重要的棉花作物品种G. barbadense和G. hirsutum。棉因此提供了一个证明性的例子，说明基本植物发现的重要性和实用性与现代技术能力相结合，以产生对进化历史的基因组洞察力。我们还回顾了我们关于美洲棉花驯化和传播考古历史的知识现状，这是一个看似不太可能的故事，涉及平行驯化起源和平行定向选择追溯到 8,000 ( G. barbadense ) 和 5,500 ( G. hirsutum )) 多年前，将两种地理上孤立的野生短日照多年生灌木转变为现代日照中性一年生植物，这些灌木具有小胶囊和种子，上面覆盖着短而棕褐色的表皮毛状体，这些一年生植物具有丰富、精细、坚固的白色纤维。这种双重驯化在几千年后发生了无意的和最近有意的种间基因渗入，因为这两个物种在不同半球的最初驯化后开始接触。因此，物种分化和生物重聚的循环被重申，这次是在异源多倍体水平上。了解这一进化历史对于我们了解世界上最重要的纤维植物的基因组结构至关重要，并有助于我们了解一般生物学原理。