Ectomycorrhiza affect architecture and nitrogen partitioning of beech (Fagus sylvatica L.) seedlings under shade and drought
Ectomycorrhiza affect architecture and nitrogen partitioning of beech (Fagus sylvatica L.) seedlings under shade and drought
复制标题
DOI：
10.1016/j.envexpbot.2012.11.005
复制
发表时间：
2013-03
影响因子：
5.7
通讯作者：
Rodica Pena;J. Simon;H. Rennenberg;A. Polle
中科院分区：
文献类型：
--
作者：
Rodica Pena;J. Simon;H. Rennenberg;A. Polle
研究了外生菌根真菌（EMF）对不同光照和水分胁迫条件下的山毛榉（Fagus sylvatica）幼苗结构和氮素分配的影响。我们假设，电动势修改生物量分配和结构的年轻山毛榉植物增加N的吸收相比，非菌根（NM）植物，因此，干旱响应EM和NM植物分歧。我们预计，充分曝光的植物更耐旱，由于改善水分状况和营养，而遮荫驯化EM植物更干旱敏感，因为减少菌根定植。为了验证这些假设，幼苗生长在原生或灭菌的森林土壤中。为了避免土壤预处理的影响NM和EM植物被移植到砂泥炭培养系统，并暴露于阴凉，干旱或两者的组合因素。遮荫导致根系生物量减少，根冠比降低。轻度干旱胁迫（黎明前水势[dmpd]=-1.3MPa）不影响生物量分配。电磁场的定植并没有增加植物的生物量，但对根构型有很大的影响：根尖数目以及绝对根长和比根长增加，因为形成细根，特别是在直径为0.2 - 0.8mm的级别。与我们的预期相反，尽管EM植物具有更大的土壤开发潜力，但灌溉良好的EM植物对氮的吸收并没有增加。总的来说，EM植物表现出较高的碳固定每单位的N比NM植物吸收和转移N分配向根。电磁场的有益影响是明显的轻度干旱下，但不同的光的可用性的反应：阴影EM植物表现出延迟的减少，光暴露EM植物表现出增加N的吸收相比，NM山毛榉。这些结果表明，电磁场参与介导不同的响应山毛榉干旱依赖于光的可用性。
The aim of this study was to investigate the influence of ectomycorrhizal fungi (EMF) on the architecture of and nitrogen (N) partitioning in young beech (Fagus sylvatica) plants in response to different light regimes and water deprivation. We hypothesized that EMF modify biomass partitioning and architecture of young beech plants by increased N uptake in comparison with non-mycorrhizal (NM) plants and that therefore, the drought responses of EM and NM plants diverge. We anticipated that full light-exposed plants were more drought tolerant due to improved water status and nutrition, whereas shade-acclimated EM plants were more drought susceptible because of decreased mycorrhizal colonization. To test these hypotheses seedlings were grown in native or sterilized forest soil. To avoid effects of soil pretreatment NM and EM plants were transplanted into sand-peat culture systems and exposed to shade, drought or the combination of both factors. Shade resulted in reduced root biomass production decreasing the root-to-shoot ratio. Mild drought stress (pre-dawn water potential [Ψpd]=−1.3MPa) did not affect biomass partitioning. EMF colonization did not increase plant biomass, but had strong effects on root architecture: the numbers of root tips as well as the absolute and specific root lengths were increased because of formation of thin roots, especially in the diameter classes from 0.2 to 0.8mm. In contrast to our expectation N uptake of well irrigated EM plants was not increased despite their larger potential for soil exploitation. Overall, EM plants exhibited higher amounts of carbon fixed per unit of N taken up than NM plants and shifted N partitioning towards the roots. Beneficial effects of EMFs were apparent under mild drought but the responses differed depending on the light availability: shaded EM plants showed a delay in the decrease of Ψpd; light exposed EM plants showed increased N uptake compared with NM beeches. These results indicate that EMFs are involved in mediating divergent responses of beech to drought depending on the light availability.