Jin-Song Chen1, Jun Li2, Yun Zhang2, Hao Zong2, Ning-Fei Lei1. 1. College of Life Science, Sichuan Normal University, Chengdu 610101, China and College of Materials and Chemistry & Chemical Engineering, Chengdu University of Technology, Chengdu 610059, China cjs74@163.com leiningfei@cdut.cn. 2. College of Life Science, Sichuan Normal University, Chengdu 610101, China and College of Materials and Chemistry & Chemical Engineering, Chengdu University of Technology, Chengdu 610059, China.
Abstract
BACKGROUND AND AIMS: Enhanced availability of photosynthates increases nitrogen (N) mineralization and nitrification in the rhizosphere via rhizodeposition from plant roots. Under heterogeneous light conditions, photosynthates supplied by exposed ramets may promote N assimilation in the rhizosphere of shaded, connected ramets. This study was conducted to test this hypothesis. METHODS: Clonal fragments of the stoloniferous herb Glechoma longituba with two successive ramets were selected. Mother ramets were subjected to full sunlight and offspring ramets were subjected to 80 % shading, and the stolon between the two successive ramets was either severed or left intact. Measurements were taken of photosynthetic and growth parameters. The turnover of available soil N was determined together with the compostion of the rhizosphere microbial community. KEY RESULTS: The microbial community composition in the rhizosphere of shaded offspring ramets was significantly altered by clonal integration. Positive effects of clonal integration were observed on NAGase activity, net soil N mineralization rate and net soil N nitrification rate. Increased leaf N and chlorophyll content as well as leaf N allocation to the photosynthetic machinery improved the photosynthetic capability of shaded offspring ramets when the stolon was left intact. Clonal integration improved the growth performance of shaded, connected offspring ramets and whole clonal fragments without any cost to the exposed mother ramets. CONCLUSIONS: Considerable differences in microbial community composition caused by clonal integration may facilitate N assimilation in the rhizosphere of shaded offspring ramets. Increased N content in the photosynthetic machinery may allow pre-acclimation to high light conditions for shaded offspring ramets, thus promoting opportunistic light capture. In accordance with the theory of the division of labour, it is suggested that clonal integration may ameliorate the carbon assimilation capacity of clonal plants, thus improving their fitness in temporally and spatially heterogeneous habitats.
BACKGROUND AND AIMS: Enhanced availability of photosynthates increases nitrogen (N) mineralization and nitrification in the rhizosphere via rhizodeposition from plant roots. Under heterogeneous light conditions, photosynthates supplied by exposed ramets may promote N assimilation in the rhizosphere of shaded, connected ramets. This study was conducted to test this hypothesis. METHODS: Clonal fragments of the stoloniferous herb Glechoma longituba with two successive ramets were selected. Mother ramets were subjected to full sunlight and offspring ramets were subjected to 80 % shading, and the stolon between the two successive ramets was either severed or left intact. Measurements were taken of photosynthetic and growth parameters. The turnover of available soil N was determined together with the compostion of the rhizosphere microbial community. KEY RESULTS: The microbial community composition in the rhizosphere of shaded offspring ramets was significantly altered by clonal integration. Positive effects of clonal integration were observed on NAGase activity, net soil N mineralization rate and net soil N nitrification rate. Increased leaf N and chlorophyll content as well as leaf N allocation to the photosynthetic machinery improved the photosynthetic capability of shaded offspring ramets when the stolon was left intact. Clonal integration improved the growth performance of shaded, connected offspring ramets and whole clonal fragments without any cost to the exposed mother ramets. CONCLUSIONS: Considerable differences in microbial community composition caused by clonal integration may facilitate N assimilation in the rhizosphere of shaded offspring ramets. Increased N content in the photosynthetic machinery may allow pre-acclimation to high light conditions for shaded offspring ramets, thus promoting opportunistic light capture. In accordance with the theory of the division of labour, it is suggested that clonal integration may ameliorate the carbon assimilation capacity of clonal plants, thus improving their fitness in temporally and spatially heterogeneous habitats.
Authors: Ian J Wright; Peter B Reich; Mark Westoby; David D Ackerly; Zdravko Baruch; Frans Bongers; Jeannine Cavender-Bares; Terry Chapin; Johannes H C Cornelissen; Matthias Diemer; Jaume Flexas; Eric Garnier; Philip K Groom; Javier Gulias; Kouki Hikosaka; Byron B Lamont; Tali Lee; William Lee; Christopher Lusk; Jeremy J Midgley; Marie-Laure Navas; Ulo Niinemets; Jacek Oleksyn; Noriyuki Osada; Hendrik Poorter; Pieter Poot; Lynda Prior; Vladimir I Pyankov; Catherine Roumet; Sean C Thomas; Mark G Tjoelker; Erik J Veneklaas; Rafael Villar Journal: Nature Date: 2004-04-22 Impact factor: 49.962
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