Elephant grass (2n = 4x = 28; Cenchrus purpureus Schumach.), also known as Napier grass, is an important forage grass and potential energy crop in tropical and subtropical regions of Asia, Africa and America. However, no study has yet reported a genome assembly for elephant grass at the chromosome scale. Here, we report a high‐quality chromosome‐scale genome of elephant grass with a total size of 1.97 Gb and a 1.5% heterozygosity rate, obtained using short‐read sequencing, single‐molecule long‐read sequencing and Hi‐C chromosome conformation capture. Evolutionary analysis showed that subgenome A' of elephant grass and pearl millet may have originated from a common ancestor more than 3.22 million years ago (MYA). Further, allotetraploid formation occurred at approximately 6.61 MYA. Syntenic analyses within elephant grass and with other grass species indicated that elephant grass has experienced chromosomal rearrangements. We found that some key enzyme‐encoding gene families related to the biosynthesis of anthocyanidins and flavonoids were expanded and highly expressed in leaves, which probably drives the production of these major anthocyanidin compounds and explains why this elephant grass cultivar has a high anthocyanidin content. In addition, we found a high copy number and transcript levels of genes involved in C₄ photosynthesis and hormone signal transduction pathways that may contribute to the fast growth of elephant grass. The availability of elephant grass genome data advances our knowledge of the genetic evolution of elephant grass and will contribute to further biological research and breeding as well as for other polyploid plants in the genus Cenchrus.

中文翻译：

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大象草（Cenchrus purpureus）基因组提供了对花色素积累和快速生长的见解

象草 (2 n  = 4 x  = 28; Cenchrus purpureusSchumach.)，又名纳皮尔草，是亚洲、非洲、美洲热带和亚热带地区重要的牧草和潜在能源作物。然而，还没有研究报告在染色体尺度上对象草进行基因组组装。在这里，我们报告了一个高质量的大象草染色体规模基因组，总大小为 1.97 Gb，杂合率为 1.5%，使用短读长测序、单分子长读长测序和 Hi-C 染色体构象捕获获得. 进化分析表明，象草和珍珠粟的亚基因组A'可能起源于322万多年前的共同祖先（MYA）。此外，异源四倍体形成发生在大约 6.61 MYA。象草和其他草种的同线分析表明象草经历了染色体重排。我们发现一些与花色素和黄酮类化合物生物合成相关的关键酶编码基因家族在叶片中扩增并高度表达，这可能推动了这些主要花色素化合物的产生，并解释了为什么这种象草品种具有高花色素含量。此外，我们发现参与 C 的基因的高拷贝数和转录水平 这可能推动了这些主要花青素化合物的产生，并解释了为什么这种象草品种的花青素含量很高。此外，我们发现参与 C 的基因的高拷贝数和转录水平 这可能推动了这些主要花青素化合物的产生，并解释了为什么这种象草品种的花青素含量很高。此外，我们发现参与 C 的基因的高拷贝数和转录水平₄可能有助于象草快速生长的光合作用和激素信号转导途径。象草基因组数据的可用性提高了我们对象草遗传进化的认识，并将有助于进一步的生物学研究和育种以及Cenchrus属的其他多倍体植物。