PDF(Pubmed)
Abstract：
Members of the Malvaceae family, including Corchorus spp., Gossypium spp., Bombax spp., and Ceiba spp., are important sources of natural fibers. In the past decade, the genomes of several Malvaceae species have been assembled; however, the evolutionary history of Malvaceae species and the differences in their fiber development remain to be clarified. Here, we report the genome assembly and annotation of two natural fiber plants from the Malvaceae, Bombax ceiba and Ceiba pentandra, whose assembled genome sizes are 783.56 Mb and 1575.47 Mb, respectively. Comparative analysis revealed that whole-genome duplication and Gypsy long terminal repeat retroelements have been the major causes of differences in chromosome number (2n = 14 to 2n = 96) and genome size (234 Mb to 2676 Mb) among Malvaceae species. We also used comparative genomic analyses to reconstruct the ancestral Malvaceae karyotype with 11 proto-chromosomes, providing new insights into the evolutionary trajectories of Malvaceae species. MYB-MIXTA-like 3 is relatively conserved among the Malvaceae and functions in fiber cell-fate determination in the epidermis. It appears to perform this function in any tissue where it is expressed, i.e. in fibers on the endocarp of B. ceiba and in ovule fibers of cotton. We identified a structural variation in a cellulose synthase gene and a higher copy number of cellulose synthase-like genes as possible causes of the finer, less spinnable, weaker fibers of B. ceiba. Our study provides two high-quality genomes of natural fiber plants and offers insights into the evolution of Malvaceae species and differences in their natural fiber formation and development through multi-omics analysis.
摘要：
锦葵科植物是天然纤维的重要来源,含有Corchorusspp.,棉属。,Bombaxspp.,Ceibaspp.,等。在过去的十年里,已经组装了几种锦葵科物种的基因组；然而，锦葵科物种的进化及其纤维发育的分化尚不清楚。这里,我们报道了两种锦葵科天然纤维植物的组装和注释，Bombaxceiba和Ceibapentandra,其基因组大小为783.56Mb和1,575.47Mb，分别。比较分析显示，全基因组复制和吉普赛长末端重复逆转录元件是锦葵科物种中染色体数量（2n=14至2n=96）和基因组大小（234Mb至2,676Mb）差异的主要原因，并报道了具有11个前染色体的Malvaceae的祖先核型，提供对进化轨迹的新见解。MYB-MIXTA样3在锦葵科物种中相对保守，具有确定表皮上纤维细胞命运的功能。它的功能可以在组织MYB-MIXTA-like3表达的任何地方实现，即B.ceiba的内果皮上的纤维和棉花的胚珠纤维。我们确定了过早终止纤维素合酶基因的结构变异和较高拷贝数的纤维素合酶样基因，这可能是B.ceiba比棉花强度更低的更细和更少的可纺纤维的原因。总之,我们的研究提供了两个高质量的天然纤维植物基因组，并通过多组学分析了解锦葵科物种的进化以及天然纤维形成和发育的分化。
