Laboratory of Fungal Biology, Institute of Microbiology, Academy of Sciences of the Czech Republic Prague, Czech Republic.
Laboratory of Fungal Biology, Institute of Microbiology, Academy of Sciences of the Czech Republic Prague, Czech Republic ; Department of Mycorrhizal Symbioses, Institute of Botany, Academy of Sciences of the Czech Republic Průhonice, Czech Republic.
Front Plant Sci. 2015 Feb 13;6:65. doi: 10.3389/fpls.2015.00065. eCollection 2015.
Plant and fungal partners in arbuscular mycorrhizal symbiosis trade mineral nutrients for carbon, with the outcome of this relationship for plant growth and nutrition being highly context-dependent and changing with the availability of resources as well as with the specific requirements of the different partners. Here we studied how the model legume Medicago truncatula, inoculated or not with a mycorrhizal fungus Rhizophagus irregularis, responded to a gradient of light intensities applied over different periods of time, in terms of growth, phosphorus nutrition and the levels of root colonization by the mycorrhizal fungus. Short-term (6 d) shading, depending on its intensity, resulted in a rapid decline of phosphorus uptake to the shoots of mycorrhizal plants and simultaneous accumulation of phosphorus in the roots (most likely in the fungal tissues), as compared to the non-mycorrhizal controls. There was, however, no significant change in the levels of mycorrhizal colonization of roots due to short-term shading. Long-term (38 d) shading, depending on its intensity, provoked a multitude of plant compensatory mechanisms, which were further boosted by the mycorrhizal symbiosis. Mycorrhizal growth- and phosphorus uptake benefits, however, vanished at 10% of the full light intensity applied over a long-term. Levels of root colonization by the mycorrhizal fungus were significantly reduced by long-term shading. Our results indicate that even short periods of shade could have important consequences for the functioning of mycorrhizal symbiosis in terms of phosphorus transfer between the fungus and the plants, without any apparent changes in root colonization parameters or mycorrhizal growth response, and call for more focused research on temporal dynamics of mycorrhizal functioning under changing environmental conditions.
植物与菌根真菌共生体在共生关系中交换矿质养分和碳，这种关系对植物生长和营养的结果高度依赖于资源的可利用性以及不同共生体的具体需求。在这里，我们研究了模式豆科植物蒺藜苜蓿在接种或不接种菌根真菌粗糙球囊霉的情况下，如何在不同时间段内，对不同光照强度梯度做出响应，包括生长、磷营养和菌根真菌对根系的定殖水平。短期（6 天）遮荫，取决于其强度，导致共生植物地上部磷吸收迅速下降，同时根部磷（很可能在真菌组织中）积累，与非菌根对照相比。然而，由于短期遮荫，根系菌根定殖水平没有显著变化。长期（38 天）遮荫，取决于其强度，引发了许多植物补偿机制，而这些机制进一步被菌根共生所促进。然而，在长期光照强度为 10%时，菌根生长和磷吸收的益处就消失了。菌根真菌对根系的定殖水平因长期遮荫而显著降低。我们的研究结果表明，即使是短期的荫蔽也可能对菌根共生体在真菌和植物之间磷转移方面的功能产生重要影响，而不会对根定植参数或菌根生长反应产生任何明显变化，并呼吁在不断变化的环境条件下，对菌根功能的时间动态进行更有针对性的研究。
