Plant Physiol.
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
QUICK SEARCH:   [advanced]


     

This Article
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in ISI Web of Science
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via ISI Web of Science (8)
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Volpin, H.
Right arrow Articles by Phillips, D. A.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Volpin, H.
Right arrow Articles by Phillips, D. A.
Agricola
Right arrow Articles by Volpin, H.
Right arrow Articles by Phillips, D. A.

Respiratory Elicitors from Rhizobium meliloti Affect Intact Alfalfa Roots1

Hanne Volpin and Donald A. Phillips*

Department of Agronomy and Range Science, University of California, Davis, California 95616

Molecules produced by Rhizobium meliloti increase respiration of alfalfa (Medicago sativa L.) roots. Maximum respiratory increases, measured either as CO2 evolution or as O2 uptake, were elicited in roots of 3-d-old seedlings by 16 h of exposure to living or dead R. meliloti cells at densities of 107 bacteria/mL. Excising roots after exposure to bacteria and separating them into root-tip- and root-hair-containing segments showed that respiratory increases occurred only in the root-hair region. In such assays, CO2 production by segments with root hairs increased by as much as 100% in the presence of bacteria. Two partially purified compounds from R. meliloti 1021 increased root respiration at very low, possibly picomolar, concentrations. One factor, peak B, resembled known pathogenic elicitors because it produced a rapid (15-min), transitory increase in respiration. A second factor, peak D, was quite different because root respiration increased slowly for 8 h and was maintained at the higher level. These molecules differ from lipo-chitin oligosaccharides active in root nodulation for the following reasons: (a) they do not curl alfalfa root hairs, (b) they are synthesized by bacteria in the absence of known plant inducer molecules, and (c) they are produced by a mutant R. meliloti that does not synthesize known lipo-chitin oligosaccharides. The peak-D compound(s) may benefit both symbionts by increasing CO2, which is required for growth of R. meliloti, and possibly by increasing the energy that is available in the plant to form root nodules.

1   This work was supported by the U.S. National Science Foundation (grant nos. IBN-92-18567 and IBN-97-22988). H.V. was supported in part by a postdoctoral award (no. FI-213-95) from the U.S.-Israel Binational Agricultural Research and Development Fund.
*   Corresponding author; e-mail daphillips{at}ucdavis.edu; fax 1-916-752-4361.

Plant Physiol. (1998) 116: 777-783
Copyright Clearance Center:   0032-0889/98/116/0777/07
© 1998 American Society of Plant Physiologists




This article has been cited by other articles:


Home page
 Plant Physiol.Home page
M'B. Tamasloukht, N. Sejalon-Delmas, A. Kluever, A. Jauneau, C. Roux, G. Becard, and P. Franken
Root Factors Induce Mitochondrial-Related Gene Expression and Fungal Respiration during the Developmental Switch from Asymbiosis to Presymbiosis in the Arbuscular Mycorrhizal Fungus Gigaspora rosea
Plant Physiology, March 1, 2003; 131(3): 1468 - 1478.
[Abstract] [Full Text] [PDF]

Home page
 Agron. J.Home page
S. Peng, J. C. Biswas, J. K. Ladha, P. Gyaneshwar, and Y. Chen
Influence of Rhizobial Inoculation on Photosynthesis and Grain Yield of Rice
Agron. J., July 1, 2002; 94(4): 925 - 929.
[Abstract] [Full Text] [PDF]

Home page
 Soil Sci.Home page
J.C. Biswas, J.K. Ladha, and F.B. Dazzo
Rhizobia Inoculation Improves Nutrient Uptake and Growth of Lowland Rice
Soil Sci. Soc. Am. J., September 1, 2000; 64(5): 1644 - 1650.
[Abstract] [Full Text]

Home page
 Proc. Natl. Acad. Sci. USAHome page
D. A. Phillips, C. M. Joseph, G.-P. Yang, E. Martinez-Romero, J. R. Sanborn, and H. Volpin
Identification of lumichrome as a Sinorhizobium enhancer of alfalfa root respiration and shoot growth
PNAS, October 26, 1999; 96(22): 12275 - 12280.
[Abstract] [Full Text] [PDF]


HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
ASPB Publications PLANT PHYSIOLOGY THE PLANT CELL
Copyright © 1998 by the American Society of Plant Biologists