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Title: Integration of C 1 and C 2 Metabolism in Trees

C 1 metabolism in plants is known to be involved in photorespiration, nitrogen and amino acid metabolism, as well as methylation and biosynthesis of metabolites and biopolymers. Although the flux of carbon through the C 1 pathway is thought to be large, its intermediates are difficult to measure and relatively little is known about this potentially ubiquitous pathway. In this study, we evaluated the C 1 pathway and its integration with the central metabolism using aqueous solutions of 13C-labeled C 1 and C 2 intermediates delivered to branches of the tropical species Inga edulis via the transpiration stream. Delivery of [ 13C]methanol and [ 13C]formaldehyde rapidly stimulated leaf emissions of [ 13C]methanol, [ 13C]formaldehyde, [ 13C]formic acid, and 13CO 2, confirming the existence of the C 1 pathway and rapid interconversion between methanol and formaldehyde. However, while [ 13C]formate solutions stimulated emissions of 13CO 2, emissions of [ 13C]methanol or [ 13C]formaldehyde were not detected, suggesting that once oxidation to formate occurs it is rapidly oxidized to CO 2 within chloroplasts. 13C-labeling of isoprene, a known photosynthetic product, was linearly related to 13CO 2 across C 1 and C 2 ([ 13C 2]acetate and [2- 13C]glycine) substrates, consistent with reassimilationmore » of C 1, respiratory, and photorespiratory CO 2. Moreover, [ 13C]methanol and [ 13C]formaldehyde induced a quantitative labeling of both carbon atoms of acetic acid emissions, possibly through the rapid turnover of the chloroplastic acetyl-CoA pool via glycolate oxidation. The results support a role of the C 1 pathway to provide an alternative carbon source for glycine methylation in photorespiration, enhance CO 2 concentrations within chloroplasts, and produce key C 2 intermediates (e.g., acetyl-CoA) central to anabolic and catabolic metabolism.« less
Authors:
 [1] ;  [2] ;  [3] ;  [2] ;  [1] ;  [1] ;  [4] ;  [5]
  1. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
  2. National Institute for Amazon Research, Manaus (Brazil)
  3. California State Univ. (CalState), Hayward, CA (United States)
  4. Estonian Univ. of Life Sciences, Tartu (Estonia); Estonian Academy of Sciences, Tallinn (Estonia)
  5. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Univ. of California, Berkeley, CA (United States)
Publication Date:
Grant/Contract Number:
AC02-05CH11231
Type:
Accepted Manuscript
Journal Name:
International Journal of Molecular Sciences (Online)
Additional Journal Information:
Journal Name: International Journal of Molecular Sciences (Online); Journal Volume: 18; Journal Issue: 10; Journal ID: ISSN 1422-0067
Publisher:
MDPI
Research Org:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23)
Country of Publication:
United States
Language:
English
Subject:
59 BASIC BIOLOGICAL SCIENCES; internal recycling of carbon; volatile emissions; central metabolism; plant growth and senescence; methanol; acetic acid
OSTI Identifier:
1419438