GENETIC STUDIES OF SYMBIOTIC NITROGEN FIXATION IN SPANISH CLOVER

1980 ◽  
Vol 60 (2) ◽  
pp. 509-518 ◽  
Author(s):  
B. R. PINCHBECK ◽  
R. T. HARDIN ◽  
F. D. COOK ◽  
I. R. KENNEDY
Keyword(s):  
Nitrogen Fixation ◽  
Genetic Variation ◽  
Symbiotic Nitrogen Fixation ◽  
Diallel Analysis ◽  
Heritable Variation ◽  
Genetic Studies ◽  
Population Means ◽  
Plant Vigor ◽  
Highly Correlated ◽  
Juvenile Plant

In this genetic study of symbiotic nitrogen fixation in the tropical legume Spanish clover (Desmodium sandwicense E. Mey), it was established that the quantitative variance found within several estimates of nitrogen fixation had a genetic basis. The diallel analysis suggested that genetic variation was present and that a major portion of this variation was attributable to differences between the parents and their F1 crosses. The within-cross genetic variation was due solely to general combining ability suggesting the presence of heritable genetic variation. Genotype by environment interactions were also found to be significant. The analysis of the data from a cross between two lines suggested that the four nitrogen fixation estimates measured were highly correlated and this variation could be represented by one principal axis of variation. Significant differences among population means were found for all analyses. Plants with larger cotyledons and juvenile leaves fixed significantly more nitrogen than did plants with smaller cotyledons and juvenile leaves. This difference was attributed to juvenile plant vigor which may assist the onset of nodulation. Analysis of the population means suggested that non-heritable variation accounted for the predominant portion of the genetic variance when the nitrogen fixation estimates were unadjusted for differences due to juvenile plant vigor. However, when the nitrogen fixation estimates were adjusted for the effects of juvenile plant vigor the genetic variation was totally heritable. Such heritable variation is of agricultural importance.

scholarly journals Plasmids Related to the Symbiotic Nitrogen Fixation Are Not Only Cooperated Functionally but Also May Have Evolved over a Time Span in Family Rhizobiaceae

2020 ◽  
Vol 12 (11) ◽  
pp. 2002-2014
Author(s):  
Ling-Ling Yang ◽  
Zhao Jiang ◽  
Yan Li ◽  
En-Tao Wang ◽  
Xiao-Yang Zhi
Keyword(s):  
Nitrogen Fixation ◽  
Gene Transfer ◽  
Horizontal Gene Transfer ◽  
Symbiotic Nitrogen Fixation ◽  
Gene Families ◽  
Time Span ◽  
Soil Conditions ◽  
Gene Gain ◽  
Nitrogen Fixing ◽  
Pan Genome

Abstract Rhizobia are soil bacteria capable of forming symbiotic nitrogen-fixing nodules associated with leguminous plants. In fast-growing legume-nodulating rhizobia, such as the species in the family Rhizobiaceae, the symbiotic plasmid is the main genetic basis for nitrogen-fixing symbiosis, and is susceptible to horizontal gene transfer. To further understand the symbioses evolution in Rhizobiaceae, we analyzed the pan-genome of this family based on 92 genomes of type/reference strains and reconstructed its phylogeny using a phylogenomics approach. Intriguingly, although the genetic expansion that occurred in chromosomal regions was the main reason for the high proportion of low-frequency flexible gene families in the pan-genome, gene gain events associated with accessory plasmids introduced more genes into the genomes of nitrogen-fixing species. For symbiotic plasmids, although horizontal gene transfer frequently occurred, transfer may be impeded by, such as, the host’s physical isolation and soil conditions, even among phylogenetically close species. During coevolution with leguminous hosts, the plasmid system, including accessory and symbiotic plasmids, may have evolved over a time span, and provided rhizobial species with the ability to adapt to various environmental conditions and helped them achieve nitrogen fixation. These findings provide new insights into the phylogeny of Rhizobiaceae and advance our understanding of the evolution of symbiotic nitrogen fixation.

scholarly journals Antioxidation and symbiotic nitrogen fixation function of prxA gene in Mesorhizobium huakuii

2019 ◽  
Vol 8 (10) ◽  
Author(s):  
Sanjiao Wang ◽  
Tiantian Lu ◽  
Qiang Xue ◽  
Ke Xu ◽  
Guojun Cheng
Keyword(s):  
Nitrogen Fixation ◽  
Symbiotic Nitrogen Fixation ◽  
Mesorhizobium Huakuii

scholarly journals Influence of PRE-emergence herbicides on soybean development, root nodulation and symbiotic nitrogen fixation

2021 ◽  
Vol 144 ◽  
pp. 105576
Author(s):  
Victor Hugo Vidal Ribeiro ◽  
Lucas Gontijo Silva Maia ◽  
Nicholas John Arneson ◽  
Maxwel Coura Oliveira ◽  
Harry Wood Read ◽  
...  
Keyword(s):  
Nitrogen Fixation ◽  
Symbiotic Nitrogen Fixation ◽  
Root Nodulation

Diallel analysis of nitrogen fixation in the rhizosphere of rice

1983 ◽  
Vol 30 (2) ◽  
pp. 129-135 ◽  
Author(s):  
S Iyama ◽  
Y Sano ◽  
T Fujii
Keyword(s):  
Nitrogen Fixation ◽  
Diallel Analysis

Overexpression of the dctA gene in Rhizobium meliloti: effect on transport of C4 dicarboxylates and symbiotic nitrogen fixation

1992 ◽  
Vol 38 (6) ◽  
pp. 555-562 ◽  
Author(s):  
Vipin Rastogi ◽  
Monika Labes ◽  
Turlough Finan ◽  
Robert Watson
Keyword(s):  
Nitrogen Fixation ◽  
Acetylene Reduction ◽  
Symbiotic Nitrogen Fixation ◽  
Plasmid Stability ◽  
Rhizobium Meliloti ◽  
Mrna Synthesis ◽  
Dicarboxylate Transport ◽  
Fusion Strain ◽  
Tryptophan Operon ◽  
Specific Mrna

Symbiotic nitrogen fixation may be limited by the transport of C4 dicarboxylates into bacteroids in the nodule for use as a carbon and energy source. In an attempt to increase dicarboxylate transport, a plasmid was constructed in which the Rhizobium meliloti structural transport gene dctA was fused to a tryptophan operon promoter from Salmonella typhimurium, trpPO. This resulted in a functional dctA gene that was no longer under the control of the dctBD regulatory genes, but the recombinant plasmid was found to be unstable in R. meliloti. To stably integrate the trpPO-dctA fusion, it was recloned into pBR325 and recombined into the R. meliloti exo megaplasmid in the dctABD region. The resultant strain showed constitutive dctA-specific mRNA synthesis which was about 5-fold higher than that found in fully induced wild-type cells. Uptake assays showed that [14C]succinate transport by the trpPO-dctA fusion strain was constitutive, and the transport rate was the same as that of induced control cells. Acetylene reduction assays indicated a significantly higher rate of nitrogen fixation in plants inoculated with the trpPO-dctA fusion strain compared with the control. Despite this apparent increase, the plants had the same top dry weights as those inoculated with control cells. Key words: acetylene reduction, genetic engineering, nodule, plasmid stability, promoter.

scholarly journals Symbiotic Nitrogen Fixation and the Challenges to Its Extension to Nonlegumes

2016 ◽  
Vol 82 (13) ◽  
pp. 3698-3710 ◽  
Author(s):  
Florence Mus ◽  
Matthew B. Crook ◽  
Kevin Garcia ◽  
Amaya Garcia Costas ◽  
Barney A. Geddes ◽  
...  
Keyword(s):  
Nitrogen Fixation ◽  
Synthetic Biology ◽  
Biological Nitrogen Fixation ◽  
Symbiotic Nitrogen Fixation ◽  
Crop Plants ◽  
Symbiotic Relationships ◽  
Mutualistic Relationship ◽  
Interest In Research ◽  
Biological Nitrogen ◽  
Developed World

ABSTRACTAccess to fixed or available forms of nitrogen limits the productivity of crop plants and thus food production. Nitrogenous fertilizer production currently represents a significant expense for the efficient growth of various crops in the developed world. There are significant potential gains to be had from reducing dependence on nitrogenous fertilizers in agriculture in the developed world and in developing countries, and there is significant interest in research on biological nitrogen fixation and prospects for increasing its importance in an agricultural setting. Biological nitrogen fixation is the conversion of atmospheric N2to NH3, a form that can be used by plants. However, the process is restricted to bacteria and archaea and does not occur in eukaryotes. Symbiotic nitrogen fixation is part of a mutualistic relationship in which plants provide a niche and fixed carbon to bacteria in exchange for fixed nitrogen. This process is restricted mainly to legumes in agricultural systems, and there is considerable interest in exploring whether similar symbioses can be developed in nonlegumes, which produce the bulk of human food. We are at a juncture at which the fundamental understanding of biological nitrogen fixation has matured to a level that we can think about engineering symbiotic relationships using synthetic biology approaches. This minireview highlights the fundamental advances in our understanding of biological nitrogen fixation in the context of a blueprint for expanding symbiotic nitrogen fixation to a greater diversity of crop plants through synthetic biology.

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