Cells Expressing ENOD2 Show Differential Spatial Organization During the Development of Alfalfa Root Nodules

1991 ◽  
Vol 4 (2) ◽  
pp. 139 ◽  
Author(s):  
Ted Allen
Keyword(s):  
Spatial Organization ◽  
Root Nodules ◽  
Alfalfa Root

Reactive oxygen species accumulation patterns of alfalfa root nodules identified using an optimized method

2019 ◽  
Vol 51 (4) ◽  
pp. 448-451
Author(s):  
Liangliang Yu ◽  
Leqi Huang ◽  
Shuang Zeng ◽  
Guirong Tang ◽  
Sunjun Wang ◽  
...  
Keyword(s):  
Reactive Oxygen Species ◽  
Root Nodules ◽  
Reactive Oxygen ◽  
Oxygen Species ◽  
Reactive Oxygen Species Accumulation ◽  
Species Accumulation ◽  
Alfalfa Root

scholarly journals Malic Enzyme Cofactor and Domain Requirements for Symbiotic N2 Fixation by Sinorhizobium meliloti

2006 ◽  
Vol 189 (1) ◽  
pp. 160-168 ◽  
Author(s):  
Michael J. Mitsch ◽  
Alison Cowie ◽  
Turlough M. Finan
Keyword(s):  
Amino Acid ◽  
Malic Enzyme ◽  
Sinorhizobium Meliloti ◽  
Symbiotic Nitrogen Fixation ◽  
Root Nodules ◽  
High Ratio ◽  
Terminal Region ◽  
Wild Type ◽  
Mutant Strains ◽  
Alfalfa Root

ABSTRACT The NAD+-dependent malic enzyme (DME) and the NADP+-dependent malic enzyme (TME) of Sinorhizobium meliloti are representatives of a distinct class of malic enzymes that contain a 440-amino-acid N-terminal region homologous to other malic enzymes and a 330-amino-acid C-terminal region with similarity to phosphotransacetylase enzymes (PTA). We have shown previously that dme mutants of S. meliloti fail to fix N2 (Fix−) in alfalfa root nodules, whereas tme mutants are unimpaired in their N2-fixing ability (Fix+). Here we report that the amount of DME protein in bacteroids is 10 times greater than that of TME. We therefore investigated whether increased TME activity in nodules would allow TME to function in place of DME. The tme gene was placed under the control of the dme promoter, and despite elevated levels of TME within bacteroids, no symbiotic nitrogen fixation occurred in dme mutant strains. Conversely, expression of dme from the tme promoter resulted in a large reduction in DME activity and symbiotic N2 fixation. Hence, TME cannot replace the symbiotic requirement for DME. In further experiments we investigated the DME PTA-like domain and showed that it is not required for N2 fixation. Thus, expression of a DME C-terminal deletion derivative or the Escherichia coli NAD+-dependent malic enzyme (sfcA), both of which lack the PTA-like region, restored wild-type N2 fixation to a dme mutant. Our results have defined the symbiotic requirements for malic enzyme and raise the possibility that a constant high ratio of NADPH + H+ to NADP in nitrogen-fixing bacteroids prevents TME from functioning in N2-fixing bacteroids.

scholarly journals Aspartate Aminotransferase in Alfalfa Root Nodules

1990 ◽  
Vol 94 (4) ◽  
pp. 1634-1640 ◽  
Author(s):  
Mark W. Farnham ◽  
Stephen M. Griffith ◽  
Susan S. Miller ◽  
Carroll P. Vance
Keyword(s):  
Aspartate Aminotransferase ◽  
Root Nodules ◽  
Alfalfa Root

scholarly journals Nitrate Metabolism in Alfalfa Root Nodules under Water Stress

1986 ◽  
Vol 37 (6) ◽  
pp. 798-806 ◽  
Author(s):  
MANUEL BECANA ◽  
PEDRO M. APARICIO-TEJO ◽  
MANUEL SÁNCHEZ-DÍAZ
Keyword(s):  
Water Stress ◽  
Root Nodules ◽  
Nitrate Metabolism ◽  
Alfalfa Root

scholarly journals Nodule-Specific Polypeptides from Effective Alfalfa Root Nodules and from Ineffective Nodules Lacking Nitrogenase

1985 ◽  
Vol 77 (4) ◽  
pp. 833-839 ◽  
Author(s):  
Naomi Lang-Unnasch ◽  
Frederick M. Ausubel
Keyword(s):  
Root Nodules ◽  
Alfalfa Root

scholarly journals ngl9: A Third MADS Box Gene Expressed in Alfalfa Root Nodules

2001 ◽  
Vol 14 (12) ◽  
pp. 1463-1467 ◽  
Author(s):  
Joseph C. Zucchero ◽  
Michal Caspi ◽  
Kathleen Dunn
Keyword(s):  
Target Genes ◽  
Root Nodules ◽  
Signal Transduction Pathway ◽  
Protein Product ◽  
Binding Activity ◽  
Mads Box ◽  
Dna Binding Activity ◽  
Mads Box Gene ◽  
Infected Cells ◽  
Alfalfa Root

Expression of MADS box genes has previously been localized to the infected cells of alfalfa (Medicago sativa) root nodules. These genes represent the first putative transcription factors to be identified in nodules and are hypothesized to be involved in a signal transduction pathway initiated by the intracellular bacterium. The eventual activation of specific target genes defines pertinent characteristics of this nitrogen-fixing differentiated cell. In this study, we identify a third nodule MADS box gene, ngl9, and demonstrate that the DNA-binding activity of its protein product is dependent on the presence of a second MADS box protein, NMH7. Despite previous results to the contrary, both genes are expressed in the early stages of flower development, further strengthening the premise that nodule developmental programming may capitalize upon existing developmental cascades.

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