High-resolution imaging of rhizosphere oxygen (O2) dynamics in Potamogeton crispus: effects of light, temperature and O2 content in overlying water
High-resolution imaging of rhizosphere oxygen (O2) dynamics in Potamogeton crispus: effects of light, temperature and O2 content in overlying water
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卷叶眼子菜根际氧 (O-2) 动态的高分辨率成像：光、温度和上覆水中 O-2 含量的影响
DOI：
10.1007/s11104-019-04150-6
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发表时间：
2019-08-01
期刊：
影响因子：
4.9
通讯作者：
Luo, Jun
中科院分区：
文献类型：
--
作者：
Han, Chao;Ren, Jinghua;Luo, Jun
目的大型植物的径向氧损失(ROL)与它们的生存和生长密切相关，因此ROL的详细特征及其在地球化学过程中的意义尤其引起人们的兴趣。我们通过实验研究了沉水植物皱纹潜水草的ROL模式，并确定了光、温度和上覆水中O-2含量如何调节根际O-2的微观分布。方法首次采用平面光学仪对种植在含底泥根管中的皱纹白杨单根周围O2的微观分布进行了无损成像。定量测定了不同光照强度(0~216 mU·m~(-2))、不同温度(14℃和25℃)和上覆水(0~256 mU·Mol~(-1))中O-2浓度和氧合膨胀的动态变化。结果在接近自然条件下(14℃光照饱和的上覆水)，根尖上皮细胞主要分布在根尖，平均速率为168.1+/-21.4nmolm(-2)S(-1)，维持了半径为1.33+/-0.21 mm的可见氧化根圈。ROL与光强密切相关，提示光合作用产生O-2。在黑暗中，根际O-2有效性显著降低，并受到上覆水中O-2含量的强烈影响，O-2被动地扩散到植物叶片中。由于周围沉积物对氧气的需求增加，温度升高导致ROL减小。结论首次证实了皱叶松根尖附近存在较高的O-2微观异质性，并提供了直接的经验证据，证明ROL受光照、温度和上覆水中O-2含量的动态调节。
Aims Radial oxygen loss (ROL) for macrophytes is intimately involved in their survival and growth, thus detailed characterizations of ROL and its implication for geochemical processes are of particular interest. We experimentally investigated ROL patterns from the submerged macrophyte species Potamogeton crispus and determined how light, temperature and O-2 content in overlying water regulate O-2 micro-distributions in the rhizosphere. Method Planar optodes were firstly used for non-destructive imaging of the O-2 micro-distributions around single roots of P. crispus planted in rhizotrons containing sediment. The dynamic changes in below-ground O-2 concentrations and oxygenation expansion at different light intensities (0-216 mu mol photons m(-2)), temperatures (14 and 25 degrees C) and O-2 content in overlying waters (0-256 mu moL(-1)) were quantified. Results P. crispus-mediated ROL is predominantly localized to the root apices with an average rate of 168.1 +/- 21.4 nmol m(-2) s(-1) under nearly natural conditions (light, saturated overlying water at 14 degrees C), maintaining a visible oxygenated rhizosphere zone with a radius of 1.33 +/- 0.21 mm. ROL is closely correlated with light intensity, suggesting photosynthetic O-2 evolution. In darkness, the rhizosphere O-2 availability is significantly reduced and strongly affected by the O-2 content in overlying water, which passively diffuses into the plant leaves. Elevated temperatures lead to diminished ROL as a result of increased O-2 demand of the surrounding sediment. Conclusion A high O-2 microheterogeneity around P. crispus root apices is firstly demonstrated, and we provide direct empirical evidences that ROL are regulated dynamically by the shifting light, temperature and O-2 content in overlying water.