Are carbon and nitrogen exchange between fungi and the orchid Goodyera repens affected by irradiance?
Are carbon and nitrogen exchange between fungi and the orchid Goodyera repens affected by irradiance?
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DOI：
10.1093/aob/mcu240
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发表时间：
2015-02-01
期刊：
影响因子：
4.2
通讯作者：
Gebauer, Gerhard
中科院分区：
文献类型：
--
作者：
Liebel, Heiko T.;Bidartondo, Martin I.;Gebauer, Gerhard
背景和目的绿兰（Goodyera repens）已被证明可以将碳转移到其菌根伙伴，因此这种通量可能受到光可用性的影响。本研究旨在测试植物与真菌之间的C和N交换是否依赖于光效，并解决开花和/或结果个体是否通过真菌到植物的C和N流量变化来补偿叶片叶绿素浓度变化的问题。方法利用植物C和N稳定同位素的天然丰度，推测5个地点兰科植物和真菌在自然辐射梯度上的通量变化。用分子分析方法鉴定了苦参根中的菌根真菌。在田间直接测定了兰花和对照植物叶片中的叶绿素浓度。关键结果：兰科植物叶片δ C-13值对光效度变化的响应与自养对照植物相似，不同菌根真菌关联对兰科植物同位素丰度模式也没有影响。开花/结实个体的叶片总氮和叶绿素浓度较低，这可能与花、种子和梢的氮素投入有关。结论根内菌根生理是相对固定的，植物与真菌间C流的量和方向变化不受光效的影响。相反，兰花可能通过增加克隆生长来对低光地点做出反应。兰花不能通过使用富含c -13和N-15的真菌源来补偿叶片总氮和叶绿素浓度的降低。
Background and Aims The green orchid Goodyera repens has been shown to transfer carbon to itsmycorrhizal partner, and this flux may therefore be affected by light availability. This study aimed to test whether the C and N exchange between plant and fungus is dependent on light availability, and in addition addressed the question of whether flowering and/or fruiting individuals of G. repens compensate for changes in leaf chlorophyll concentration with changes in C and N flows from fungus to plant.Methods The natural abundances of stable isotopes of plant C and N were used to infer changes in fluxes between orchid and fungus across natural gradients of irradiance at five sites. Mycorrhizal fungi in the roots of G. repens were identified by molecular analyses. Chlorophyll concentrations in the leaves of the orchid and of reference plants were measured directly in the field.Key Results Leaf delta C-13 values of G. repens responded to changes in light availability in a similar manner to autotrophic reference plants, and different mycorrhizal fungal associations also did not affect the isotope abundance patterns of the orchid. Flowering/fruiting individuals had lower leaf total N and chlorophyll concentrations, which is most probably explained by N investments to form flowers, seeds and shoot.Conclusions The results indicate that mycorrhizal physiology is relatively fixed in G. repens, and changes in the amount and direction of C flow between plant and fungus were not observed to depend on light availability. The orchid may instead react to low-light sites through increased clonal growth. The orchid does not compensate for low leaf total N and chlorophyll concentrations by using a C-13-and N-15-enriched fungal source.