Ammonium effects on function and structure of nitrogen-fixing root nodules of Alnus incana (L.) Moench

Planta ◽  
1982 ◽  
Vol 156 (4) ◽  
pp. 332-340 ◽  
Author(s):  
Kerstin Huss-Danell ◽  
Anita Sellstedt ◽  
Anita Flower-Ellis ◽  
Michael Sj�str�m
Keyword(s):  
Root Nodules ◽  
Alnus Incana ◽  
Nitrogen Fixing

Nitrogenase activity in response to restricted shoot growth in Alnus incana

1983 ◽  
Vol 61 (11) ◽  
pp. 2949-2955 ◽  
Author(s):  
Kerstin Huss-Danell ◽  
Anita Sellstedt
Keyword(s):  
Root Biomass ◽  
Shoot Growth ◽  
Nitrogenase Activity ◽  
Root Nodules ◽  
Alnus Incana ◽  
Nitrogen Fixing ◽  
Combined Nitrogen ◽  
Carbon Compounds ◽  
Source Sink ◽  
Nitrogen Percentage

In the Alnus–Frankia symbiosis the nitrogen-fixing root nodules are one of the sinks for carbon compounds newly formed in photosynthesis and exported from the leaves (source). The competition for assimilates between shoot tips and root nodules was studied by reducing shoot growth. Cloned plants of Alnus incana (L.) Moench were grown without combined nitrogen in a growth chamber. Shoot growth was inhibited by excision of all buds or by induced dormancy. The experiments showed an increased root biomass in the treated plants, indicating a changed source–sink balance. The treatments never caused an increased nitrogenase activity (C2H2-dependent C2H4 production); rather it was decreased. The nitrogenase activity was always correlated with leaf areas. It was also correlated with growth, which is shown by the similar nitrogen percentage in intact and treated plants.

scholarly journals Development of the nitrogen-fixing and protein-synthesizing apparatus of bacteroids in pea root nodules

1979 ◽  
Vol 562 (3) ◽  
pp. 515-526 ◽  
Author(s):  
T. Bisseling ◽  
R.C. Van Den Bos ◽  
M.W. Weststrate ◽  
M.J.J. Hakkaart ◽  
A. Van Kammen
Keyword(s):  
Root Nodules ◽  
Nitrogen Fixing ◽  
Pea Root

scholarly journals A New Species of Devosia That Forms a Unique Nitrogen-Fixing Root-Nodule Symbiosis with the Aquatic Legume Neptunia natans (L.f.) Druce

2002 ◽  
Vol 68 (11) ◽  
pp. 5217-5222 ◽  
Author(s):  
Raul Rivas ◽  
Encarna Velázquez ◽  
Anne Willems ◽  
Nieves Vizcaíno ◽  
Nanjappa S. Subba-Rao ◽  
...  
Keyword(s):  
Root Nodule ◽  
Root Nodules ◽  
Infection Process ◽  
Nitrogen Fixing ◽  
Rhizobium Tropici ◽  
Rdna Sequences ◽  
Root Nodule Symbiosis ◽  
16S Rdna Sequences ◽  
The Common ◽  
Nodule Symbiosis

ABSTRACT Rhizobia are the common bacterial symbionts that form nitrogen-fixing root nodules in legumes. However, recently other bacteria have been shown to nodulate and fix nitrogen symbiotically with these plants. Neptunia natans is an aquatic legume indigenous to tropical and subtropical regions and in African soils is nodulated by Allorhizobium undicola. This legume develops an unusual root-nodule symbiosis on floating stems in aquatic environments through a unique infection process. Here, we analyzed the low-molecular-weight RNA and 16S ribosomal DNA (rDNA) sequence of the same fast-growing isolates from India that were previously used to define the developmental morphology of the unique infection process in this symbiosis with N. natans and found that they are phylogenetically located in the genus Devosia, not Allorhizobium or Rhizobium. The 16S rDNA sequences of these two Neptunia-nodulating Devosia strains differ from the only species currently described in that genus, Devosia riboflavina. From the same isolated colonies, we also located their nodD and nifH genes involved in nodulation and nitrogen fixation on a plasmid of approximately 170 kb. Sequence analysis showed that their nodD and nifH genes are most closely related to nodD and nifH of Rhizobium tropici, suggesting that this newly described Neptunia-nodulating Devosia species may have acquired these symbiotic genes by horizontal transfer.

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