College of Landscape Architecture, Sichuan Agricultural University, Chengdu, China.
College of Life Science, Sichuan Normal University, Chengdu, China.
Sci Total Environ. 2018 Jul 1;628-629:594-602. doi: 10.1016/j.scitotenv.2018.02.002. Epub 2018 Feb 20.
Clonal integration plays an important role in clonal plant adapting to heterogeneous habitats. It was postulated that clonal integration could exhibit positive effects on nitrogen cycling in the rhizosphere of clonal plant subjected to heterogeneous light conditions. An in-situ experiment was conducted using clonal fragments of Phyllostachys bissetii with two successive ramets. Shading treatments were applied to offspring or mother ramets, respectively, whereas counterparts were treated to full sunlight. Rhizomes between two successive ramets were either severed or connected. Extracellular enzyme activities and nitrogen turnover were measured, as well as soil properties. Abundance of functional genes (archaeal or bacterial amoA, nifH) in the rhizosphere of shaded, offspring or mother ramets were determined using quantitative polymerase chain reaction. Carbon or nitrogen availabilities were significantly influenced by clonal integration in the rhizosphere of shaded ramets. Clonal integration significantly increased extracellular enzyme activities and abundance of functional genes in the rhizosphere of shaded ramets. When rhizomes were connected, higher nitrogen turnover (nitrogen mineralization or nitrification rates) was exhibited in the rhizosphere of shaded offspring ramets. However, nitrogen turnover was significantly decreased by clonal integration in the rhizosphere of shaded mother ramets. Path analysis indicated that nitrogen turnover in the rhizosphere of shaded, offspring or mother ramets were primarily driven by the response of soil microorganisms to dissolved organic carbon or nitrogen. This unique in-situ experiment provided insights into the mechanism of nutrient recycling mediated by clonal integration. It was suggested that effects of clonal integration on the rhizosphere microbial processes were dependent on direction of photosynthates transport in clonal plant subjected to heterogeneous light conditions.
克隆整合在克隆植物适应异质生境中起着重要作用。有人假设，在异质光照条件下，克隆整合可以对克隆植物根际的氮循环产生积极影响。本研究利用具有两个连续分株的刚竹克隆片段进行了原位实验。分别对后代或母分株进行遮荫处理，而对照则进行全光照处理。两个连续分株之间的根茎要么被切断，要么被连接。测量了根际的胞外酶活性和氮转化，以及土壤性质。利用定量聚合酶链反应测定了遮荫、后代或母分株根际中功能基因（古菌或细菌 amoA、nifH）的丰度。碳或氮的可利用性在遮荫分株的根际中受到克隆整合的显著影响。克隆整合显著增加了遮荫分株根际的胞外酶活性和功能基因的丰度。当根茎相连时，遮荫后代分株根际的氮转化（氮矿化或硝化速率）更高。然而，克隆整合显著降低了遮荫母分株根际的氮转化。路径分析表明，遮荫、后代或母分株根际的氮转化主要受土壤微生物对溶解有机碳或氮的响应驱动。这项独特的原位实验深入了解了克隆整合介导的养分循环回收机制。研究表明，在异质光照条件下，克隆整合对根际微生物过程的影响取决于光合作用产物在克隆植物中的运输方向。
