目的:根和根茎对于克隆植物适应土壤水分梯度至关重要。龙稻,根茎状的野生稻,由于其在非生物胁迫条件下的恢复力,因此对多年生水稻育种特别感兴趣。虽然根系对土壤洪水的反应得到了充分研究,根茎对水梯度的响应仍未充分开发。我们假设长水稻的生理整合通过相互联系的根茎缓解了异质水分亏缺胁迫,根和根茎都对不同的水条件作出反应。
方法:我们研究了母株和分株之间的生理整合,测量关键光合参数(光合和蒸腾速率,和气孔导度)使用红外气体分析仪。此外,根和根茎对三种水情的响应(洪水,充分浇水,和水分亏缺)通过测量径向失水和对O2的表观渗透以及组织化学和解剖学特征来检查。
结果:我们的实验强调了通过相互联系的根茎进行生理整合在减轻水分亏缺胁迫中的作用。从暴露于水分亏缺条件的母株或分株切断根茎连接导致关键光合参数显着降低,强调根茎连接在双向缓解应激中的重要性。此外,O.longstaminata根茎表现出本构性的次生质障碍和木质化的质质障碍,而这些障碍是在水分胁迫下在根系中诱导的。解剖学上,根茎和根对水分梯度的反应相似,在缺水条件下显示较小的直径,在洪水条件下显示较大的直径。
结论:我们的发现表明,通过相互联系的根茎的生理整合有助于减轻水分亏缺胁迫时,无论是母株还是分株正在经历水分亏缺,而对方处于控制状态。此外,O.longistaminata可以通过调节根和根茎的解剖和生理特性来适应各种土壤水分状况。
OBJECTIVE: Roots and rhizomes are critical for the adaptation of clonal plants to soil water gradients. Oryza longistaminata, a rhizomatous wild rice, is of particular interest for perennial rice breeding due to its resilience under abiotic stress conditions. While root responses to soil
flooding are well-studied, rhizome responses to water gradients remain underexplored. We hypothesize that physiological integration of Oryza longistaminata mitigates heterogeneous water deficit stress through interconnected rhizomes, and both roots and rhizomes respond to contrasting water conditions.
METHODS: We investigated the physiological integration between mother plants and ramets, measuring key photosynthetic parameters (photosynthetic and transpiration rate, and stomatal conductance) using an Infrared Gas Analyzer. Moreover, root and rhizome responses to three water regimes (
flooding, well-watered, and water deficit) were examined by measuring radial water loss and apparent permeance to O2, along with histochemical and anatomical characterization.
RESULTS: Our experiment highlights the role of physiological integration via interconnected rhizomes in mitigating water deficit stress. Severing rhizome connections from mother plants or ramets exposed to water deficit conditions led to significant decreases in key photosynthetic parameters, underscoring the importance of rhizome connections in bidirectional stress mitigation. Additionally, O. longistaminata rhizomes exhibited constitutive suberized and lignified apoplastic barriers, while such barriers were induced in roots under water stress. Anatomically, both rhizomes and roots respond similarly to water gradients, showing thinner diameters under water deficit conditions and larger diameters under
flooding conditions.
CONCLUSIONS: Our findings indicate that physiological integration through interconnected rhizomes helps alleviate water deficit stress when either the mother plant or the ramet is experiencing water deficit, while the counterpart is in control conditions. Moreover, O. longistaminata can adapt to various soil water regimes by regulating anatomical and physiological traits of roots and rhizomes.