Using a physiological framework for improving the detection of quantitative trait loci related to nitrogen nutrition in Medicago truncatula

Moreau, D. and Burstin, J. and Aubert, G. and et al, . (2012) Using a physiological framework for improving the detection of quantitative trait loci related to nitrogen nutrition in Medicago truncatula. Theoretical and Applied Genetics , 124 (4). pp. 755-768.

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Medicago truncatula is used as a model plant for exploring the genetic and molecular determinants of nitrogen (N) nutrition in legumes. In this study, our aim was to detect quantitative trait loci (QTL) controlling plant N nutrition using a simple framework of carbon/N plant functioning stemming from crop physiology. This framework was based on efficiency variables which delineated the plant's efficiency to take up and process carbon and N resources. A recombinant inbred line population (LR4) was grown in a glasshouse experiment under two contrasting nitrate concentrations. At low nitrate, symbiotic N(2) fixation was the main N source for plant growth and a QTL with a large effect located on linkage group (LG) 8 affected all the traits. Significantly, efficiency variables were necessary both to precisely localize a second QTL on LG5 and to detect a third QTL involved in epistatic interactions on LG2. At high nitrate, nitrate assimilation was the main N source and a larger number of QTL with weaker effects were identified compared to low nitrate. Only two QTL were common to both nitrate treatments: a QTL of belowground biomass located at the bottom of LG3 and another one on LG6 related to three different variables (leaf area, specific N uptake and aboveground:belowground biomass ratio). Possible functions of several candidate genes underlying QTL of efficiency variables could be proposed. Altogether, our results provided new insights into the genetic control of N nutrition in M. truncatula. For instance, a novel result for M. truncatula was identification of two epistatic interactions in controlling plant N(2) fixation. As such this study showed the value of a simple conceptual framework based on efficiency variables for studying genetic determinants of complex traits and particularly epistatic interactions.

Item Type: Article
Additional Information: We thank P. Mathey, C. Jeudy, V. Durey, A. Larmure, A.L. Santoni, V. Pellissier, F. Strbik, H. Busset, F. Monraisin and S. Brunel-Muguet for their excellent technical assistance, S. Jasson, B. Mangin, A. Bordat and V. Savois for their help in QTL detection, B. Julier and B. Teulat-Merah for useful discussions about QTL analysis. We also thank R. Thompson for critical reading of the manuscript and its improvement. This work was supported by the European Project Grain Legumes (FP6-20 02-FOOD-1-506223), UNIP (Union Nationale Interprofessionnelle des plantes riches en ProteĀ“ines) and the Regional Council of Burgundy (France).
Uncontrolled Keywords: Medicago truncatula, Genomic research, Nitrogen nutrition
Author Affiliation: INRA, France.
Subjects: Crop Improvement
Divisions: Other Crops
Depositing User: Mr Arbind Seth
Date Deposited: 19 Feb 2013 15:01
Last Modified: 19 Feb 2013 15:01
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