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Contribution of current carbon assimilation in supplying root exudates of Lolium perenne measured using steady‐state 13 C labelling
Author(s) -
Thornton Barry,
Paterson Eric,
Midwood Andrew J.,
Sim Allan,
Pratt Shona M.
Publication year - 2004
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1111/j.0031-9317.2004.00250.x
Subject(s) - exudate , lolium perenne , assimilation (phonology) , botany , labelling , biology , steady state (chemistry) , poaceae , chemistry , philosophy , linguistics , biochemistry
Coupling growth of Lolium perenne L. in sterile solution culture with steady‐state 13 CO 2 labelling allowed quantification of the contribution of C, assimilated either before or after a specific time point, both to plant compartments and root exudates. Plants were grown for 27 days in atmospheres containing CO 2 with δ 13 C signatures of either −13.5 or −36.1‰. Air supplies to plants were then reciprocally switched to the opposing signature (day 0), plants were destructively harvested and root exudates collected over the next 8 days. Following the switch, C assimilated after day 0 and transported to the roots initially only appeared in root tips, later appearing in both tip and non‐tip material. The δ 13 C signature of the root exudate changed exponentially with time. Assimilation pre‐ and post‐day 0 contributed equally to exudate C at 4.5 days. Beyond day 8, assimilation pre‐day 0 still contributed 41.7% of exudate C. Over all 8 days, a linear relationship existed between the δ 13 C signatures of root tips and exudate, suggesting that all newly assimilated C in the exudate was from root tips. Results imply pulse‐labelling approaches to study root exudates are discriminative in the sources of exudates labelled and in the sites from which exudation occurs.