Sirov Dagmara, Borovec Jakub, Picek Tom X, Adamec Lubom R, Nedbalov Linda, Vrba Jaroslav
Faculty of Science, University of South Bohemia, Department of Ecosystem Biology, Branišovská 31, CZ-37005 České Budějovice, Czech Republic.
Institute of Botany AS CR, Dukelská 135, CZ-37982 Třeboň, Czech Republic.
Funct Plant Biol. 2011 Jul;38(7):583-593. doi: 10.1071/FP11023.
Rootless aquatic carnivorous Utricularia exude up to 25% of their photosynthates into the trap lumen, which also harbours a complex microbial community thought to play a role in enhancing Utricularia nutrient acquisition. We investigated the composition of organic carbon in the trap fluid, its availability for microbial uptake, the influence of plant nutrient status and trap age on its biodegradability, and the composition of prokaryotic assemblages within the traps of three aquatic Utricularia species. Using ion chromatography and basal respiration rate measurements we confirmed that up to 30% of total dissolved organic carbon in Utricularia trap fluid in oligotrophic conditions was easily biodegradable compounds commonly found in plant root exudates (mainly glucose, fructose and lactate). The proportion of these compounds and their microbial utilisation decreased with increasing mineral nutrient supply and trap age. Fluorescence in situ hybridisation analyses showed that microbial trap assemblages are dominated by alpha and beta Proteobacteria, and that the assemblage composition is affected by changes in the ambient mineral nutrient supply. We suggest that organic carbon dynamics within the traps, involving both the plant and associated microbial assemblages, underlies the acquisition of key nutrients by Utricularia and may help explain the evolutionary success of the genus.
无根水生食肉植物狸藻将高达25%的光合产物分泌到捕虫囊腔中，该腔还栖息着一个复杂的微生物群落，据认为该群落对增强狸藻的养分获取起作用。我们研究了捕虫囊液中有机碳的组成、其对微生物摄取的可用性、植物养分状况和捕虫囊年龄对其生物降解性的影响，以及三种水生狸藻物种捕虫囊内原核生物群落的组成。通过离子色谱法和基础呼吸速率测量，我们证实，在贫营养条件下，狸藻捕虫囊液中高达30%的总溶解有机碳是植物根分泌物中常见的易生物降解化合物（主要是葡萄糖、果糖和乳酸）。随着矿质养分供应和捕虫囊年龄的增加，这些化合物的比例及其微生物利用率降低。荧光原位杂交分析表明，捕虫囊内的微生物群落以α-变形菌纲和β-变形菌纲为主，且群落组成受周围矿质养分供应变化的影响。我们认为，捕虫囊内的有机碳动态，涉及植物和相关微生物群落，是狸藻获取关键养分的基础，并可能有助于解释该属在进化上的成功。
