Hyphal contribution to water uptake in mycorrhizal plants as affected by the fungal species and water status
Hyphal contribution to water uptake in mycorrhizal plants as affected by the fungal species and water status
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DOI：
10.1111/j.1399-3054.1995.tb00865.x
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发表时间：
1995-03
影响因子：
6.4
通讯作者：
J. M. Ruiz-Lozano;R. Azcón
中科院分区：
文献类型：
--
作者：
J. M. Ruiz-Lozano;R. Azcón
Vasicular-arbuscular mycorrhiza可能通过多种机制提高植物的抗旱性，如增加根系导水率、气孔调节、菌丝吸水和渗透调节。然而，泡囊丛枝菌根（VAM）菌丝对水分吸收的实质性贡献尚未得到明确证明。本研究的目的是研究菌丝从两个VAM真菌的水分吸收和运输的寄主植物的贡献。生菜（Lactuca saliva L.）植物生长在由筛网分成两个隔室的容器中。一个被根占据，另一个只被VAM菌丝占据，屏幕允许通过。根由VAM真菌Glomus deserticola或Glomus fasciculatum定殖，或留下未接种但补充P。将水供应到距离筛网（根）10 cm处的菌丝隔室。在菌丝室内测定了3种不同水分处理下VAM和P处理的CO2交换速率、水分利用效率、蒸腾速率、气孔导度和光合磷利用效率。结果表明，在VAM植物中，大部分水分被菌丝吸收。VAM植物，有机会进入菌丝室，有较高的水分和养分含量。G. deserticola在水分限制条件下能有效地发挥作用，G.束生植物对培养基中的水分非常敏感。VAM行为的这种差异反映了每种真菌根据土壤水分水平的不同能力。不同能力的具体菌丝体也表示在营养和叶片气体交换参数。G. fasciculatum的净光合速率和水分利用效率显著高于G. deserticola和磷施肥植物。相比之下，G.荒漠化处理对N、P、K营养、叶片导度和蒸腾作用的影响最大。由于两种内生菌的根内和根外菌丝延伸没有差异，结果表明，菌根菌丝可以吸收水分，这两种VAM真菌的行为和它们对植物水分关系的影响所涉及的机制有相当大的变化。
Vesicular-arbuscular mycorrhizae may increase resistance of plants to drought by a number of mechanisms, such as increased root hydraulic conductivity, stomatal regulation, hyphal water uptake and osmotic adjustment. However, a substantial contribution of vesicular-arbuscular mycorrhizal (VAM) hyphae to water uptake has not been demonstrated unequivocally. The objective of this investigation was to examine the contribution of hyphae from two VAM fungi to water uptake and transport by the host plant. Lettuce (Lactuca saliva L.) plants were grown in a container divided by a screen into two compartments. One was occupied by roots, the other only by VAM hyphae, which the screen permitted to pass. Roots were colonized by the VAM fungi Glomus deserticola or Glomus fasciculatum, or were left uninoculated but P-supplemented. Water was supplied to the hyphal compartment at a distance of 10 cm from the screen (root). CO 2 exchange rate, water-use efficiency, transpiration, stomatal conductance and photosynthetic phosphorus-use efficiency of VAM or P-amended control plants were evaluated at three levels of water application in the hyphal compartment. Results indicate that much of the water was taken up by the hyphae in VAM plants. VAM plants, which had access to the hyphal compartment, had higher water and nutrient contents. G. deserticola functioned efficiently under water limitation and mycelium from G. fasciculatum-colonized plants was very sensitive to water in the medium. This discrepancy in VAM behaviour reflects the various abilities of each fungus according to soil water levels. Different abilities of specific mycelia were also expressed in terms of nutritional and leaf gas-exchange parameters. G. fasciculatum caused a significant increase in net photosynthesis and rate of water use efficiency compared to G. deserticola and P-fertilized plants. In contrast, the G. deserticola treatment was the most efficient affecting N, P and K nutrition, leaf conductance and transpiration. Since no differences in the intra- and extra-radical hyphal extension of the two endophytes were found, the results demonstrate that mycorrhizal hyphae can take up water and that there are considerable variations in both the behaviour of these two VAM fungi and in the mechanisms involved in their effects on plant water relations.