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The presence of nodules on legume root systems can alter phenotypic plasticity in response to internal nitrogen independent of nitrogen fixation
Author(s) -
Goh ChooiHua,
Nicotra Adrienne B.,
Mathesius Ulrike
Publication year - 2016
Publication title -
plant, cell and environment
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.646
H-Index - 200
eISSN - 1365-3040
pISSN - 0140-7791
DOI - 10.1111/pce.12672
Subject(s) - rhizobia , medicago truncatula , biology , legume , symbiosis , root nodule , nitrogen fixation , medicago sativa , botany , inoculation , shoot , agronomy , horticulture , bacteria , genetics
All higher plants show developmental plasticity in response to the availability of nitrogen (N) in the soil. In legumes, N starvation causes the formation of root nodules, where symbiotic rhizobacteria fix atmospheric N 2 for the host in exchange for fixed carbon (C) from the shoot. Here, we tested whether plastic responses to internal [N] of legumes are altered by their symbionts. Glasshouse experiments compared root phenotypes of three legumes, Medicago truncatula , Medicago sativa and Trifolium subterraneum , inoculated with their compatible symbiont partners and grown under four nitrate levels. In addition, six strains of rhizobia, differing in their ability to fix N 2 in M . truncatula , were compared to test if plastic responses to internal [N] were dependent on the rhizobia or N 2 ‐fixing capability of the nodules. We found that the presence of rhizobia affected phenotypic plasticity of the legumes to internal [N], particularly in root length and root mass ratio (RMR), in a plant species‐dependent way. While root length responses of M . truncatula to internal [N] were dependent on the ability of rhizobial symbionts to fix N 2 , RMR response to internal [N] was dependent only on initiation of nodules, irrespective of N 2 ‐fixing ability of the rhizobia strains.