Carbon Metabolism and Bacteroid Functioning Are Involved in the Regulation of Nitrogen Fixation in Medicago truncatula Under Drought and Recovery

Author(s): Estibaliz Larrainzar, Stefanie Wienkoop, Christian Scherling, Stefan Kempa, Ruben Ladrera, Cesar Arrese-Igor, Wolfram Weckwerth, Esther M. Gonzalez
Abstract: Regulation of symbiotic nitrogen fixation (SNF) during drought stress is complex and not yet fully understood. In the present work, the involvement of nodule C and N metabolism in the regulation of SNF in Medicago truncatula under drought and a subsequent rewatering treatment was analyzed using a combination of metabolomic and proteomic approaches. Drought induced a reduction of SNF rates and major changes in the metabolic profile of nodules, mostly an accumulation of amino acids (Pro, His, and Trp) and carbohydrates (sucrose, galactinol, raffinose, and trehalose). This accumulation was coincidental with a decline in the levels of bacteroid proteins involved in SNF and C metabolism, along with a partial reduction of the levels of plant sucrose synthase 1 (SuSy1). In contrast, the variations in enzymes related to N assimilation were found not to correlate with the reduction in SNF, suggesting that these enzymes do not have a role in the regulation of SNF. Unlike the situation in other legumes such as pea and soybean, the drought-induced inhibition of SNF in M. truncatula appears to be caused by impairment of bacteroid metabolism and N2-fixing capacity rather than a limitation of respiratory substrate.
Organisation(s)
External organisation(s): Universidad Pública de Navarra, Max-Planck-Institut für Molekulare Pflanzenphysiologie
Journal: Molecular Plant - Microbe Interactions
Volume: 22
Pages: 1565-1576
No. of pages: 12
ISSN: 0894-0282
Publication date: 2009
Peer reviewed: Yes
Austrian Fields of Science 2012: 106002 Biochemistry, 106030 Plant ecology, 106022 Microbiology, 106031 Plant physiology
Portal url: https://ucrisportal.univie.ac.at/en/publications/aadd405c-63e9-49b5-adc5-9190c374f44b