Miscanthus species are perennial C4 grasses that are considered promising energy crops because of their high biomass yields, excellent adaptability and low management costs. Miscanthus lutarioriparius and Miscanthus sacchariflorus are closely related subspecies that are distributed in different habitats. However, there are only a few reports on the mechanisms by which Miscanthus adapts to different environments. Here, comparative transcriptomic and morphological analyses were used to study the evolutionary adaptation of M. lutarioriparius and M. sacchariflorus to different habitats. In total, among 7586 identified orthologs, 2060 orthologs involved in phenylpropanoid biosynthesis and plant hormones were differentially expressed between the two species. Through an analysis of the Ka/Ks ratios of the orthologs, we estimated that the divergence time between the two species was approximately 4.37 Mya. In addition, 37 candidate positively selected orthologs (PSGs) that played important roles in the adaptation of these species to different habitats were identified. Then, the expression levels of 20 PSGs in response to flooding and drought stress were analyzed, and the analysis revealed significant changes in their expression levels. These results facilitate our understanding of the evolutionary adaptation to habitats and the speciation of M. lutarioriparius and M. sacchariflorus. We hypothesise that lignin synthesis genes are the main cause of the morphological differences between the two species. In summary, the plant nonspecific phospholipase C gene family and the receptor-like protein kinase gene family played important roles in the evolution of these two species.

芒草属多年生C4禾本科植物，因其生物量高、适应性强、管理成本低而被认为是很有前景的能源作物。Miscanthus lutarioriparius和Miscanthus sacchariflorus是分布在不同栖息地的密切相关的亚种。然而，关于芒草适应不同环境的机制的报道很少。在这里，比较转录组学和形态学分析用于研究M. lutarioriparius和M. sacchariflorus的进化适应到不同的栖息地。总共在 7586 个已鉴定的直系同源物中，2060 个参与苯丙烷类生物合成和植物激素的直系同源物在两个物种之间差异表达。通过对直系同源物的 Ka/Ks 比率的分析，我们估计这两个物种之间的分歧时间约为 4.37 Mya。此外，还确定了 37 个候选正选择直系同源物 (PSG)，它们在这些物种适应不同栖息地的过程中发挥了重要作用。然后，分析了响应洪水和干旱胁迫的 20 个 PSG 的表达水平，分析显示它们的表达水平发生了显着变化。这些结果有助于我们理解对栖息地的进化适应和M. lutarioriparius和M. sacchariflorus。我们假设木质素合成基因是两个物种之间形态差异的主要原因。综上所述，植物非特异性磷脂酶C基因家族和受体样蛋白激酶基因家族在这两个物种的进化过程中发挥了重要作用。