Systemic and local effects of long-term application of nitrate on nodule growth and N<sub>2</sub>fixation in soybean (<i>Glycine max</i>[L.] Merr.)

Yashima, Hiroyuki; Fujikake, Hiroyuki; Sato, Takashi; Ohtake, Norikuni; Sueyoshi, Kuni; Ohyama, Takuji

doi:10.1080/00380768.2003.10410344

Cited by 27 publications

(23 citation statements)

References 22 publications

(22 reference statements)

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“…The seeds were inoculated with a suspension of rhizobium strain NM353 (∼10 8 cells·L −1 ) and sown in a sterilized quartzite bed. Plants were grown in a greenhouse under natural light conditions for 4 d; then, seedlings at the same growth stage were transplanted to a two-layered pot system (42), in which the upper pot was filled with 500 mL quartzite medium, and the lower pot was filled with 1 L nutrient solution (P, 250 μM; K, 1,850 μM; Fe, 100 μM; Mg, 100 μM; Mn, 1 μM; Zn, 1 μM; Cu, 0.1 μM; Mo, 0.005 μM). NO 3 − was applied in culture solution at levels of 0, 1, or 2 mM; 3 d later, 10 mL rhizobium suspension was added to each upper pot.…”

Section: Methodsmentioning

confidence: 99%

Root exudates drive interspecific facilitation by enhancing nodulation and N ₂ fixation

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

339

186

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Plant diversity in experimental systems often enhances ecosystem productivity, but the mechanisms causing this overyielding are only partly understood. Intercropping faba beans (Vicia faba L.) and maize (Zea mays L.) result in overyielding and also, enhanced nodulation by faba beans. By using permeable and impermeable root barriers in a 2-y field experiment, we show that root-root interactions between faba bean and maize significantly increase both nodulation and symbiotic N 2 fixation in intercropped faba bean. Furthermore, root exudates from maize promote faba bean nodulation, whereas root exudates from wheat and barley do not. Thus, a decline of soil nitrate concentrations caused by intercropped cereals is not the sole mechanism for maize promoting faba bean nodulation. Intercropped maize also caused a twofold increase in exudation of flavonoids (signaling compounds for rhizobia) in the systems. Roots of faba bean treated with maize root exudates exhibited an immediate 11-fold increase in the expression of chalcone-flavanone isomerase (involved in flavonoid synthesis) gene together with a significantly increased expression of genes mediating nodulation and auxin response. After 35 d, faba beans treated with maize root exudate continued to show up-regulation of key nodulation genes, such as early nodulin 93 (ENOD93), and promoted nitrogen fixation. Our results reveal a mechanism for how intercropped maize promotes nitrogen fixation of faba bean, where maize root exudates promote flavonoid synthesis in faba bean, increase nodulation, and stimulate nitrogen fixation after enhanced gene expression. These results indicate facilitative root-root interactions and provide a mechanism for a positive relationship between species diversity and ecosystem productivity.flavanoids | gene expression | intercropping | root-root interactions | signals M any ecosystems, including grasslands (1, 2), forests (3), phytoplankton communities (4), and cropping systems (5), show a positive relationship between plant diversity and ecosystem productivity. Several mechanisms have been proposed to explain this relationship. A "sampling effect" occurs, because more diverse mixtures have a higher probability of containing a species with higher productivity (6). Complementarity effects occur when species vary in resource use and niche differentiation in space or time, leading to greater resource utilization (6-9). Facilitation occurs when one species increases the growth of other species through a wide range of processes (10). Facilitative effects may be direct (e.g., by shade or protection from harsh conditions) or indirect (e.g., when one species reduces attack by pathogens or herbivores on other species) (11-13).Legume/cereal intercropping systems have been widely studied in the context of diversity and ecosystem function and commonly overyield, because dinitrogen (N 2 ) fixation by legumes increases ecosystem nitrogen (N) supply (7,8), an example of facilitation. This facilitation is important to agriculture on a large scale, because app...

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Section: Methodsmentioning

confidence: 99%

Root exudates drive interspecific facilitation by enhancing nodulation and N ₂ fixation

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

339

186

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“…An open question is whether Parasponia nodulation is somehow less advanced than in legumes (Behm et al, 2014): our results point to similar levels of nodulation control as found in some legume species. Specifically, it has been shown that at high nitrogen levels, legumes can control nodule formation and mass-a process known as autoregulation of nodulation (Cho and Harper, 1991;Sueyoshi et al, 2003;Jeudy et al, 2010). This has also been demonstrated in nodulated actinorhizal plants, which likewise show a reduced investment in nodulation with application of exogenous nitrogen (Kohls and Baker, 1989;Thomas and Berry, 1989;Arnone et al, 1994;Markham and Zekveld, 2007;Wall and Berry, 2007).…”

Section: Discussionmentioning

confidence: 96%

The Non-Legume Parasponia andersonii Mediates the Fitness of Nitrogen-Fixing Rhizobial Symbionts Under High Nitrogen Conditions

2020

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Organisms rely on symbiotic associations for metabolism, protection, and energy. However, these intimate partnerships can be vulnerable to exploitation. What prevents microbial mutualists from parasitizing their hosts? In legumes, there is evidence that hosts have evolved sophisticated mechanisms to manage their symbiotic rhizobia, but the generality and evolutionary origins of these control mechanisms are under debate. Here, we focused on the symbiosis between Parasponia hosts and N 2-fixing rhizobium bacteria. Parasponia is the only non-legume lineage to have evolved a rhizobial symbiosis and thus provides an evolutionary replicate to test how rhizobial exploitation is controlled. A key question is whether Parasponia hosts can prevent colonization of rhizobia under high nitrogen conditions, when the contribution of the symbiont becomes nonessential. We grew Parasponia andersonii inoculated with Bradyrhizobium elkanii under four ammonium nitrate concentrations in a controlled growth chamber. We measured shoot and root dry weight, nodule number, nodule fresh weight, nodule volume. To quantify viable rhizobial populations in planta, we crushed nodules and determined colony forming units (CFU), as a rhizobia fitness proxy. We show that, like legumes and actinorhizal plants, P. andersonii is able to control nodule symbiosis in response to exogenous nitrogen. While the relative host growth benefits of inoculation decreased with nitrogen fertilization, our highest ammonium nitrate concentration (3.75 mM) was sufficient to prevent nodule formation on inoculated roots. Rhizobial populations were highest in nitrogen free medium. While we do not yet know the mechanism, our results suggest that control mechanisms over rhizobia are not exclusive to the legume clade.

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“…When nitrate was supplied to the hydroponically grown soybean roots, the nitrate in-hibition on nodule growth and nitrogen fixation was shown to be rapid and reversible [22][23][24]. On the other hand, indirect or systemic effect of nitrate, which means the effect of nitrate absorbed from distant part of the roots, depended on the site, duration and concentrations of nitrate supply [37,38]. The indirect effect of nitrate was investigated by a two-layered pot system separating the upper roots and lower roots.…”

Section: Effect Of Combined Nitrogen On Nodule Growth and Nitrogen Fimentioning

confidence: 99%

Soybean Seed Production and Nitrogen Nutrition

Ohyama¹,

Minagawa²,

Ishikawa³

et al. 2013

A Comprehensive Survey of International Soybean Research - Genetics, Physiology, Agronomy and Nitrogen Relationships

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Systemic and local effects of long-term application of nitrate on nodule growth and N₂fixation in soybean (Glycine max[L.] Merr.)

Cited by 27 publications

References 22 publications

Root exudates drive interspecific facilitation by enhancing nodulation and N ₂ fixation

Root exudates drive interspecific facilitation by enhancing nodulation and N ₂ fixation

The Non-Legume Parasponia andersonii Mediates the Fitness of Nitrogen-Fixing Rhizobial Symbionts Under High Nitrogen Conditions

Soybean Seed Production and Nitrogen Nutrition

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Systemic and local effects of long-term application of nitrate on nodule growth and N2fixation in soybean (Glycine max[L.] Merr.)

Cited by 27 publications

References 22 publications

Root exudates drive interspecific facilitation by enhancing nodulation and N 2 fixation

Root exudates drive interspecific facilitation by enhancing nodulation and N 2 fixation

The Non-Legume Parasponia andersonii Mediates the Fitness of Nitrogen-Fixing Rhizobial Symbionts Under High Nitrogen Conditions

Soybean Seed Production and Nitrogen Nutrition

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Systemic and local effects of long-term application of nitrate on nodule growth and N₂fixation in soybean (Glycine max[L.] Merr.)

Root exudates drive interspecific facilitation by enhancing nodulation and N ₂ fixation

Root exudates drive interspecific facilitation by enhancing nodulation and N ₂ fixation