The State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, Hubei, China.
College of Advanced Agricultural Sciences, University of Chinese Academy of Sciences, Beijing, China.
Plant Cell Environ. 2024 Dec;47(12):4720-4740. doi: 10.1111/pce.15050. Epub 2024 Jul 30.
Heterophylly is a phenomenon whereby an individual plant dramatically changes leaf shape in response to the surroundings. Hygrophila difformis (Acanthaceae; water wisteria), has recently emerged as a model plant to study heterophylly because of its striking leaf shape variation in response to various environmental factors. When submerged, H. difformis often develops complex leaves, but on land it develops simple leaves. Leaf complexity is also influenced by other factors, such as light density, humidity, and temperature. Here, we sequenced and assembled the H. difformis chromosome-level genome (scaffold N50: 60.43 Mb, genome size: 871.92 Mb), which revealed 36 099 predicted protein-coding genes distributed over 15 pseudochromosomes. H. difformis diverged from its relatives during the Oligocene climate-change period and expanded gene families related to its amphibious habit. Genes related to environmental stimuli, leaf development, and other pathways were differentially expressed in submerged and terrestrial conditions, possibly modulating morphological and physiological acclimation to changing environments. We also found that auxin plays a role in H. difformis heterophylly. Finally, we discovered candidate genes that respond to different environmental conditions and elucidated the role of LATE MERISTEM IDENTITY 1 (LMI1) in heterophylly. We established H. difformis as a model for studying interconnections between environmental adaptation and morphogenesis.
异形叶性是一种现象，即个体植物的叶片形状会因周围环境的变化而发生显著变化。水鳖科的异叶水蓑衣（Hygrophila difformis）因其对各种环境因素的反应而具有显著的叶片形状变化，最近已成为研究异形叶性的模式植物。当浸没在水中时，异叶水蓑衣通常会发育出复杂的叶片，但在陆地上则会发育出简单的叶片。叶片复杂性还受到其他因素的影响，例如光密度、湿度和温度。在这里，我们对异叶水蓑衣进行了染色体水平的基因组测序和组装（scaffold N50：60.43 Mb，基因组大小：871.92 Mb），揭示了 36099 个预测的蛋白编码基因分布在 15 条假染色体上。异叶水蓑衣在渐新世气候变化时期与其亲缘关系分化，并扩展了与两栖习性相关的基因家族。与环境刺激、叶片发育和其他途径相关的基因在浸没和陆地条件下表达不同，可能调节对环境变化的形态和生理适应。我们还发现生长素在异叶水蓑衣异形叶性中发挥作用。最后，我们发现了响应不同环境条件的候选基因，并阐明了晚期分生组织身份 1（LMI1）在异形叶性中的作用。我们确立了异叶水蓑衣作为研究环境适应与形态发生之间相互关系的模式植物。
