DataSheet_1_Molecular basis of genetic plasticity to varying environmental conditions on growing rice by dry/direct-sowing and exposure to drought stress: Insights for DSR varietal development.pdf

Rice requires plenty of water for its cultivation by transplanting. This poses several challenges to its cultivation due to erratic rainfall resulting in drought, flood, and other abiotic stresses of varying intensity. Dry/direct-sown rice (DSR) has emerged as a water-saving/climate-smart alternative to transplanted rice (TPR). The performance of a rice cultivar on growing by different methods of planting under varying environmental conditions varies considerably. However, the molecular basis of the observed phenotypic plasticity of rice to varying environmental conditions is still elusive. Resilience to various environmental fluctuations is important to ensure sustainable rice production in the present era of global climate change. Our observations on exclusively up-regulated genes in leaf of Nagina 22 (N 22) grown by dry/direct-sowing and subjected to drought stress at panicle initiation stage (compared to that in leaf of IR 64), and another set of genes exclusively down-regulated in leaf of N 22 (compared to that in leaf of IR 64) indicate important roles of leaf in stress resilience. A large number of genes down-regulated exclusively in root of N 22 on dry/direct-sowing subjected to drought stress indicates a major contribution of roots in stress tolerance. The genes for redox-homeostasis, transcription factors, stress signaling, carbohydrate metabolism, and epigenetic modifications play important roles in making N 22 better adapted to DSR conditions. More importantly, the involvement of genes in rendering genetic plasticity to N 22 under changing environmental conditions was confirmed by reversal of the method of planting. To the best of our knowledge, this is the first report on decoding the molecular basis of genetic plasticity of rice grown by two different methods of planting subjected to drought stress at the reproductive stage of plant growth. This might help in DSR varietal development program to enhance water-productivity, conserve natural resources, and minimize the emission of greenhouse gases, thus achieving the objectives of negative-emission agriculture.

水稻移栽栽培需消耗大量水资源。但降雨分布不均引发干旱、洪涝及不同强度的其他非生物胁迫，给移栽水稻种植带来诸多挑战。旱直播水稻（Dry/direct-sown rice, DSR）已成为移栽水稻（Transplanted rice, TPR）的节水型气候友好型替代种植方案。不同种植方式下，水稻品种在多变环境中的生长表现差异显著。然而，水稻应对多变环境的表型可塑性（phenotypic plasticity）背后的分子机制仍未明确。在全球气候变化的当下，提升水稻对环境波动的抗逆能力，是保障水稻可持续生产的关键。我们对孕穗期遭受干旱胁迫的旱直播Nagina 22（N 22）叶片（相较于IR 64叶片）中特异性上调基因的观察，以及该品种叶片中另一组特异性下调基因的分析，均表明叶片在抗逆性中发挥重要作用。旱直播且经受干旱胁迫的N 22根系中大量特异性下调基因，则揭示了根系在耐逆性中的核心贡献。氧化还原稳态、转录因子、胁迫信号传导、碳水化合物代谢及表观遗传修饰相关基因，在N 22适应旱直播环境的过程中扮演关键角色。更为重要的是，通过反转种植方式的实验，证实了相关基因在N 22应对环境变化时赋予其遗传可塑性的功能。据我们所知，本研究首次解析了两种种植方式下，生殖生长期遭受干旱胁迫的水稻遗传可塑性的分子机制。该研究可为旱直播水稻品种选育工作提供参考，以提升水分生产效率、保护自然资源并减少温室气体排放，最终实现负排放农业的目标。