Isolation and Initial Characterization of Constitutive Nitrate Reductase-Deficient Mutants NR328 and NR345 of Soybean (Glycine max).

Botany Department, Australian National University, Canberra ACT 2600, Australia.
Plant physiology (Impact Factor: 6.56). 07/1986; 81(2):572-6. DOI: 10.1104/pp.81.2.572
Source: PubMed

ABSTRACT Two nitrate reductase deficient mutants of soybean (Glycine max [L.] Merr. cv Bragg) were isolated from approximately 10,000 M(2) seedlings, using a direct enzymic assay in microtiter plates. Stable inheritance of NR345 and NR328 phenotypes has been demonstrated through to the M(5) generation. Both mutants were affected in constitutive nitrate reductase activity. Assayable activities of cNR in nitrate-free grown seedlings was about 3 to 4% of the control for NR345 and 14 to 16% of the control for NR328. Both mutants expressed inducible NR during early plant development and were sensitive to nitrate and urea inhibition of nodulation. These new mutants will allow an extension of the characterization of nitrate reductases and their function in soybean. Preliminary evidence indicates that NR345 is similar to the previously isolated mutant nr(1), while NR328 is different.

  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Combined nitrogen (N) sources are known to strongly affect initiation, development and functioning of Nitrogen-Fixing-Nodules whose formation is triggered by lipochitin-oligosaccharide signals secreted in the rhizospere by the Rhizobium partner. The rapid effects of N supply on nodule initiation have been mainly described when N sources are present at the moment of Rhizobium inoculation or purified Nod Factors addition. We recently reported that high ammonium nitrate growth conditions might also strongly affect the nodulation competence of Lotus japonicus plants, prior to the Rhizobium inoculation. This is a long-term effect, which suggests a change of the general nutritional status as the signal controlling the reduced nodulation capacities. The mechanisms underlying these inhibitory pathways are apparently different and the identification of the molecular actors involved may provide new insights into the linkage between N environmental changes and root organogenesis programs.
    Plant signaling & behavior 12/2009; 4(11):1066-8.
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Root development is remarkably sensitive to variations in the supply and distribution of inorganic nutrients in the soil. Here we review examples of the ways in which nutrients such as N, P, K and Fe can affect developmental processes such as root branching, root hair production, root diameter, root growth angle, nodulation and proteoid root formation. The nutrient supply can affect root development either directly, as a result of changes in the external concentration of the nutrient, or indirectly through changes in the internal nutrient status of the plant. The direct pathway results in developmental responses that are localized to the part of the root exposed to the nutrient supply; the indirect pathway produces systemic responses and seems to depend on long-distance signals arising in the shoot. We propose the term `trophomorphogenesis' to describe the changes in plant morphology that arise from variations in the availability or distribution of nutrients in the environment. We discuss what is currently known about the mechanisms of external and internal nutrient sensing, the possible nature of the long-distance signals and the role of hormones in the trophomorphogenic response.
    Plant and Soil 01/2001; 232(1):51-68. · 3.24 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Ten of 11 supernodulating mutants of soybean [Glycine max (L.) Merr.] cv. Bragg, in which nodulation was far in excess of that in the wild type, showed pronounced tolerance of nodulation to applied nitrate. Mutant nts (nitrate-tolerant symbiosis) 1116 had an intermediate nodulation response and also showed some inhibition by nitrate. Mutant 1029, a revertant of nts382 (an extreme supernodulator), showed a wild-type nodulation pattern and was equally sensitive to nitrate as cv. Bragg. Grafting experiments with cv. Bragg and nts382 indicated that both supernodulation and tolerance of nodulation to nitrate were dependent on shoot factors. Total leaf nitrate reductase (EC and EC activity of the supernodulating mutants was similar to that in cv. Bragg. We conclude from these results that the inhibitory effect of nitrate on nodule initiation and development in soybean depends on an interaction between nitrate and the autoregulation singal. In the supernodulating mutants, the autoregulation signal is either altered or absent and cosequently nodulation in these mutants is not sensitive to nitrate.
    Physiologia Plantarum 04/2006; 75(1):37 - 42. · 3.66 Impact Factor


Available from