Friend or Foe-Light Availability Determines the Relationship between Mycorrhizal Fungi, Rhizobia and Lima Bean (Phaseolus lunatus L.).
Friend or Foe-Light Availability Determines the Relationship between Mycorrhizal Fungi, Rhizobia and Lima Bean (Phaseolus lunatus L.).
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DOI：
10.1371/journal.pone.0154116
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发表时间：
2016
期刊：
影响因子：
3.7
通讯作者：
Kautz S
中科院分区：
文献类型：
--
作者：
Ballhorn DJ;Schädler M;Elias JD;Millar JA;Kautz S
植物与根微生物的关系代表了地球上一些最重要的共生关系。固氮根瘤菌和丛枝菌根真菌（AMF）在促进植物健康的同时，也需要大量的碳水化合物分配来交换关键的营养物质。尽管植物通常可以补偿碳损失，但当植物无法广泛增加光合作用时，在光限制下可能会出现限制。在这种情况下，维持共生关系的成本可能超过收益，将互利微生物变成寄生虫，导致植物生长和繁殖减少。在自然系统中，植物通常与不同的共生体同时生长，这些共生体也可能相互作用。这可能会增加这种多方关系的反应的复杂性。我们用利马豆（Phaseolus lunatus）进行了实验，它有效地与两种类型的根共生体形成了联系。我们采用全光照和低光照的微生物接种的四个处理。经过14周的孵化期，我们量化了地上和地下的植物生物量和种子的数量和活力，以确定联合接种和光照处理对植物适合度的影响。在光限制条件下，营养和繁殖性状抑制AMF和根瘤菌接种利马豆植物相对于对照（非殖民化植物）。引人注目的是，减少种子产量是最关键的组合处理根瘤菌x AMF。我们的研究结果表明，微生物根共生体产生的附加成本，导致在光限制条件下植物健身下降。
Plant associations with root microbes represent some of the most important symbioses on earth. While often critically promoting plant fitness, nitrogen-fixing rhizobia and arbuscular mycorrhizal fungi (AMF) also demand significant carbohydrate allocation in exchange for key nutrients. Though plants may often compensate for carbon loss, constraints may arise under light limitation when plants cannot extensively increase photosynthesis. Under such conditions, costs for maintaining symbioses may outweigh benefits, turning mutualist microbes into parasites, resulting in reduced plant growth and reproduction. In natural systems plants commonly grow with different symbionts simultaneously which again may interact with each other. This might add complexity to the responses of such multipartite relationships. We experimented with lima bean (Phaseolus lunatus), which efficiently forms associations with both types of root symbionts. We applied full light and low-light to each of four treatments of microbial inoculation. After an incubation period of 14 weeks, we quantified vegetative aboveground and belowground biomass and number and viability of seeds to determine effects of combined inoculant and light treatment on plant fitness. Under light-limited conditions, vegetative and reproductive traits were inhibited in AMF and rhizobia inoculated lima bean plants relative to controls (un-colonized plants). Strikingly, reductions in seed production were most critical in combined treatments with rhizobia x AMF. Our findings suggest microbial root symbionts create additive costs resulting in decreased plant fitness under light-limited conditions.