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Movement of newly assimilated 13 C carbon in the grass Lolium perenne and its incorporation into rhizosphere microbial DNA
Author(s) -
Clayton S. J.,
Clegg C. D.,
Bristow A. W.,
Gregory P. J.,
Headon D. M.,
Murray P. J.
Publication year - 2010
Publication title -
rapid communications in mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.528
H-Index - 136
eISSN - 1097-0231
pISSN - 0951-4198
DOI - 10.1002/rcm.4392
Subject(s) - rhizosphere , lolium perenne , microcosm , chemistry , lolium , population , soil respiration , shoot , biomass (ecology) , botany , stable isotope probing , agronomy , poaceae , respiration , microorganism , bacteria , environmental chemistry , biology , demography , sociology , genetics
One of the key processes that drives rhizosphere microbial activity is the exudation of soluble organic carbon (C) by plant roots. We describe an experiment designed to determine the impact of defoliation on the partitioning and movement of C in grass ( Lolium perenne L.), soil and grass‐sterile sand microcosms, using a 13 CO 2 pulse‐labelling method. The pulse‐derived 13 C in the shoots declined over time, but that of the roots remained stable throughout the experiment. There were peaks in the atom% 13 C of rhizosphere CO 2 in the first few hours after labelling probably due to root respiration, and again at around 100 h. The second peak was only seen in the soil microcosms and not in those with sterilised sand as the growth medium, indicating possible microbial activity. Incorporation of the 13 C label into the microbial biomass increased at 100 h when incorporation into replicating cells, as indicated by the amounts of the label in the microbial DNA, started to increase. These results indicate that the rhizosphere environment is conducive to bacterial growth and replication. The results also show that defoliation had no impact on the pattern of movement of 13 C from plant roots into the microbial population in the rhizosphere. Copyright © 2010 John Wiley & Sons, Ltd.