This Article Full Text Full Text (PDF) Supplemental Data All Versions of this Article: 145/4/1600    most recent pp.107.106955v1 Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via CrossRef Citing Articles via Web of Science (7) Citing Articles via Google Scholar Google Scholar Articles by Baier, M. C. Articles by Hohnjec, N. Search for Related Content PubMed PubMed Citation Articles by Baier, M. C. Articles by Hohnjec, N. Agricola Articles by Baier, M. C. Articles by Hohnjec, N. Related Collections Legume Biology

PLANTS INTERACTING WITH OTHER ORGANISMS

Antisense Repression of the Medicago truncatula Nodule-Enhanced Sucrose Synthase Leads to a Handicapped Nitrogen Fixation Mirrored by Specific Alterations in the Symbiotic Transcriptome and Metabolome^1,[W]

Institute for Genome Research and Systems Biology (M.C.B., H.K., N.H.), International Graduate School in Bioinformatics and Genome Research (A.B., H.K., N.H.), and Department of Proteome and Metabolome Research (A.B.), Center for Biotechnology, Bielefeld University, D–33594 Bielefeld, Germany

We analyzed the role of the sucrose (Suc) synthase MtSucS1 during nodulation of the model legume Medicago truncatula, integrating data for the developmental, transcriptional, and metabolic processes affected downstream of an impaired Suc cleavage in root nodules. To reduce carbohydrate supply to nodule tissues, transgenic plants expressing a p35S-driven MtSucS1-antisense fusion were constructed. These plants displayed an up to 90% reduction of MtSucS1 proteins in roots and nodules. Phenotypic studies of two independent MtSucS1-reduced lines demonstrated that only under conditions depending on nodulation, these plants appeared to be impaired in above-ground growth. Specifically plant height, shoot weight, leaf development, flowering, as well as seed maturation were reduced, and the efficiency of photosynthesis was affected. Concomitantly, a significantly enhanced root to shoot ratio with a marked increase in root tip numbers was observed. Root nodule formation was found retarded and the impaired nodulation was accompanied by a less efficient nitrogen (N) acquisition. The decreased total N content of MtSucS1-antisense lines and an enhanced carbon to N ratio in roots, nodules, and shoots correlated with the extent of MtSucS1 knockdown. On the level of transcription, effects of an MtSucS1 reduction were evident for genes representing important nodes of the nodule carbon and N metabolism, while metabolite profiling revealed significantly lower levels of amino acids and their derivatives particularly in strongly MtSucS1-reduced nodules. Our results support the model that nodule-enhanced Suc synthase 1 of the model legume M. truncatula is required for the establishment and maintenance of an efficient N-fixing symbiosis.

The author responsible for distribution of materials integral to the findings presented in this article in accordance with the policy described in the Instructions for Authors (www.plantphysiol.org) is: Helge Küster (helge.kuester{at}genetik.uni-bielefeld.de).

^[W] The online version of this article contains Web-only data.

www.plantphysiol.org/cgi/doi/10.1104/pp.107.106955

^* Corresponding author; e-mail helge.kuester{at}genetik.uni-bielefeld.de.

Received August 6, 2007; accepted October 17, 2007; published October 19, 2007.

This article has been cited by other articles:

				S. A. Fischinger, M. Hristozkova, Z.-A. Mainassara, and J. Schulze Elevated CO2 concentration around alfalfa nodules increases N2 fixation J. Exp. Bot., October 8, 2009; (2009) erp287v1. [Abstract] [Full Text] [PDF]

				T. Welham, J. Pike, I. Horst, E. Flemetakis, P. Katinakis, T. Kaneko, S. Sato, S. Tabata, J. Perry, M. Parniske, et al. A cytosolic invertase is required for normal growth and cell development in the model legume, Lotus japonicus J. Exp. Bot., August 1, 2009; 60(12): 3353 - 3365. [Abstract] [Full Text] [PDF]

				C. Chang, I. Damiani, A. Puppo, and P. Frendo Redox Changes during the Legume-Rhizobium Symbiosis Mol Plant, May 1, 2009; 2(3): 370 - 377. [Abstract] [Full Text] [PDF]