Instituto de Investigaciones en Ecosistemas y Sustentabilidad, Universidad Nacional Autónoma de México-Campus Morelia, Apartado Postal 27-3 Santa María de Guido, 58090, Morelia, Michoacán, Mexico.
Mycorrhiza. 2019 Mar;29(2):141-147. doi: 10.1007/s00572-019-00880-8. Epub 2019 Jan 14.
Most studies dealing with mycorrhizal associations and drought have focused on the plants, not on the fungi, and tolerance and adaptations of arbuscular mycorrhizal (AM) fungi to cope with water stress are virtually unknown. This study was conducted to assess how water stress directly affects an AM fungus isolate, particularly through morphological and physiological changes in the external mycelium. We used two-compartment pots separated by mesh and an air gap that allowed us to apply water stress treatments only to the external mycelium. Clover (Trifolium subterraneum L.) plants inoculated with Rhizophagus intraradices grew at high humidity until external mycorrhizal mycelium developed in the mycelium compartment. Then, we started three watering treatments: high (H, 70% of soil water holding capacity), low (L, 10%), and mixed watering (HLHL, 70-10-70-10%) only in the hyphal compartment. The HLHL treatment was rewetted once to 70% after 42 days. We measured total mycelium length, hyphal length in diameter categories, respiration activity, and protoplasm fragmentation 42 and 76 days after starting the treatments. Rhizophagus intraradices mycelium responded to water stress by reducing its length, maintaining larger diameter hyphae, and concentrating protoplasm activity in fragments in the HLHL and L treatments. In both water stress treatments, changes suggested a trade-off between avoiding desiccation and storing resources, and maintaining soil exploration and water uptake capacity.
大多数涉及菌根共生体和干旱的研究都集中在植物上，而不是真菌上，对于丛枝菌根（AM）真菌如何耐受和适应水分胁迫几乎一无所知。本研究旨在评估水分胁迫如何直接影响 AM 真菌分离物，特别是通过外部菌丝的形态和生理变化。我们使用两个隔室盆，通过网眼和空气隙隔开，仅在外部菌丝隔室中施加水分胁迫处理。接种了内根结瘤菌（Rhizophagus intraradices）的三叶草（Trifolium subterraneum L.）植物在高湿度下生长，直到外部菌根菌丝在菌丝隔室中发育。然后，我们开始了三种浇水处理：高（H，土壤持水能力的 70%）、低（L，10%）和混合浇水（HLHL，70-10-70-10%），仅在菌丝隔室中进行。HLHL 处理在 42 天后重新湿润至 70%。我们在处理开始后 42 天和 76 天测量了总菌丝长度、直径类别的菌丝长度、呼吸活性和原生质片段化。内根结瘤菌的菌丝对水分胁迫的反应是通过减少其长度、保持较大直径的菌丝以及在 HLHL 和 L 处理中浓缩原生质活性来实现的。在这两种水分胁迫处理中，变化表明在避免干燥和储存资源以及维持土壤探索和吸水能力之间存在权衡。
