PDF(Pubmed)
Abstract：
Alfalfa (Medicago sativa L.) is one of the most important forage legumes in the world, including autotetraploid (M. sativa ssp. sativa) and diploid alfalfa (M. sativa ssp. caerulea, progenitor of autotetraploid alfalfa). Here, we reported a high-quality genome of ZW0012 (diploid alfalfa, 769 Mb, contig N50 = 5.5 Mb), which was grouped into the Northern group in population structure analysis, suggesting that our genome assembly filled a major gap among the members of M. sativa complex. During polyploidization, large phenotypic differences occurred between diploids and tetraploids, and the genetic information underlying its massive phenotypic variations remains largely unexplored. Extensive structural variations (SVs) were identified between ZW0012 and XinJiangDaYe (an autotetraploid alfalfa with released genome). We identified 71 ZW0012-specific PAV genes and 1296 XinJiangDaYe-specific PAV genes, mainly involved in defence response, cell growth, and photosynthesis. We have verified the positive roles of MsNCR1 (a XinJiangDaYe-specific PAV gene) in nodulation using an Agrobacterium rhizobia-mediated transgenic method. We also demonstrated that MsSKIP23_1 and MsFBL23_1 (two XinJiangDaYe-specific PAV genes) regulated leaf size by transient overexpression and virus-induced gene silencing analysis. Our study provides a high-quality reference genome of an important diploid alfalfa germplasm and a valuable resource of variation landscape between diploid and autotetraploid, which will facilitate the functional gene discovery and molecular-based breeding for the cultivars in the future.
摘要：
紫花苜蓿(MedicagosativaL.)是世界上最重要的牧草豆科植物之一。包括同源四倍体(M.sativassp.紫花苜蓿)和二倍体苜蓿(M.sativassp.Caerulea,同源四倍体苜蓿的祖先）。这里,我们报道了ZW0012的高质量基因组(二倍体苜蓿，769Mb,重叠群N50=5.5Mb)，在人口结构分析中被分为北方组，这表明我们的基因组组装填补了水稻复合体成员之间的一个主要空白。在多倍体化过程中,二倍体和四倍体之间发生了巨大的表型差异，其巨大的表型变异背后的遗传信息在很大程度上仍未被探索。在ZW0012和新江大叶（具有释放基因组的同源四倍体苜蓿）之间鉴定出广泛的结构变异（SV）。我们鉴定了71个ZW0012特异性PAV基因和1296个新降大叶特异性PAV基因，主要涉及防御反应，细胞生长,和光合作用。我们已经使用根瘤菌农杆菌介导的转基因方法验证了MsNCR1（新江大叶特异性PAV基因）在结瘤中的积极作用。我们还证明了MsSKIP23_1和MsFBL23_1（两个新姜大叶特异性PAV基因）通过瞬时过表达和病毒诱导的基因沉默分析来调节叶片大小。我们的研究为重要的二倍体苜蓿种质提供了高质量的参考基因组，并为二倍体和同源四倍体之间的变异景观提供了宝贵的资源。这将促进未来品种的功能基因发现和分子育种。
