Characteristics of initial growth of hypernodulation soybean mutants, NOD1-3, NOD2-4 and NOD3-7, affected by inoculation of bradyrhizobia and nitrate supply

Abstract

The characteristics of plant growth of hypernodulation soybean mutant lines NOD1-3, NOD2-4 and NOD3-7 were compared with their parent cv. Williams. The plants were grown using hydroponics in an illuminated growth chamber with or without seed inoculation of bradyrhizobia, and in the absence or presence of nitrate in the culture solution. When the plants were grown without inoculation, the total dry weight of all mutant lines was not different statistically from Williams, both in the absence and presence of nitrate. When they were grown with inoculation of bradyrhizobia, however, the total dry weight of each mutant line was significantly lower than that of Williams, both in the absence and presence of nitrate.These results indicate that the reduced accumulation of total dry matter of hypernodulation mutant lines compared with the wild type may be a secondary effect passively resulting from the large number of nodules, while the hypernodulation trait is a primary effect of the mutated gene. When the plants were grown with inoculation, the nodule number was decreased by the presence of nitrate in Williams, NOD1-3 and NOD2-4, but not in NOD3-7. NOD3-7 may be the most tolerant to nitrate inhibition of nodulation among the NOD mutant lines. In contrast, leaf growth of NOD3-7 and NOD1-3 was different from the wild type; the expanded leaf was smaller, but the leaf emergence rate was faster compared with Williams under all conditions. This indicates that NOD3-7 and NOD1-3 might decrease the ability for leaf expansion or may have a faster leaf emergence rate.

Involvement of polyamines in the root nodule regulation of soybeans (Glycine max)

“…It is postulated that signals related to the autoregulation might not be specific only to the nodulation but also be a part of general plant development (Beveridge et al 2007, Buzas and. Ito et al (2007Ito et al ( , 2008 recently suggested that the root-derived autoregulation signal induces the leaf expansion, especially the cell proliferation of leaf blade. Inhibition of the root growth and stimulation of the shoot growth, both of which are induced by the foliarly applied polyamines as described above, might closely link to the suppression of nodule formation.…”

Autoregulation of Nodulation in Soybean Plants

“…Next, characteristics of the initial growth of NOD mutant lines were compared with Williams at 17 or 18 days after sowing [35]. The plants were grown with or without seed-inoculation of bradyrhizobia, and in the absence or presence of nitrate in the culture solution.…”

Unleashing the potential of the root hair cell as a single plant cell type model in root systems biology

“…Compared to these mutants, 4.4- to 7-fold fewer nodules were counted on wild type root system (22.8 ± 9.25 nodules per plant). Although, we found that the number of nodules per root system is lower in the aeroponic system grown plants compared to vermiculite grown plants (i.e., wild type, NOD1-3, NOD2-4, and NOD3-7 mutants showed 67, 441, 344, and 143 nodules per plant, 17–18 days after inoculation, respectively; Ito et al, 2007 ), the NOD hypernodulating phenotype is observed in the aeroponic system. These data support that this technology is fully compatible with the analysis of the early and late stages of legume nodulation.…”

“…; (3) inoculation of plants with pathogenic and symbiotic microorganisms. The latter was validated by inoculating 2 weeks-old root systems of the hypernodulation soybean mutants [i.e., NOD1-3, NOD2-4, and NOD3-7; Ito et al, 2007 ] with a bacterial suspension of B. japonicum , the soybean nitrogen-fixing symbiont. As soon as 10 days after inoculation, nodules emerged.…”