Oxygen Responses, Hemoglobin, And The Structure And Function Of Vesicles

Silvester, Warwick B.; Berg, R. Howard; Schwintzer, Christa R.; Tjepkema, John D.

doi:10.1007/978-1-4020-3547-0_5

Cited by 15 publications

(19 citation statements)

References 112 publications

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“…Superficially, this seems inconsistent with a single gain of nodulation. However, hemoglobin is not crucial for all nitrogen-fixing nodule symbioses because several Frankia microsymbionts possess intrinsic physical characteristics to protect the Nitrogenase enzyme for oxidation ( 67 – 70 ). In line with this, Ceanothus spp.…”

Section: Discussionmentioning

confidence: 99%

Comparative genomics of the nonlegume Parasponia reveals insights into evolution of nitrogen-fixing rhizobium symbioses

Velzen

Holmer

et al. 2018

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

216

378

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SignificanceFixed nitrogen is essential for plant growth. Some plants, such as legumes, can host nitrogen-fixing bacteria within cells in root organs called nodules. Nodules are considered to have evolved in parallel in different lineages, but the genetic changes underlying this evolution remain unknown. Based on gene expression in the nitrogen-fixing nonlegume Parasponia andersonii and the legume Medicago truncatula, we find that nodules in these different lineages may share a single origin. Comparison of the genomes of Parasponia with those of related nonnodulating plants reveals evidence of parallel loss of genes that, in legumes, are essential for nodulation. Taken together, this raises the possibility that nodulation originated only once and was subsequently lost in many descendant lineages.

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Section: Discussionmentioning

confidence: 99%

Comparative genomics of the nonlegume Parasponia reveals insights into evolution of nitrogen-fixing rhizobium symbioses

Velzen

Holmer

et al. 2018

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

216

378

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“…The non‐legume Parasponia is unique in forming nodules with bradyrhizobia, whereas actinorhizal nodules are elicited by Frankia . Unlike other actinorhizal nodules, Frankia strains do not form vesicles to protect nitrogenase in Casuarina nodules, which may be linked to the abundance of Cgla2 in the cytosol (Fleming et al , ; Silvester et al , ). By contrast, a Glb has been found at low concentration in nodules of Alnus glutinosa , although it may be a truncated Glb of Frankia (Silvester et al , ).…”

Section: Globins In Symbiosismentioning

confidence: 99%

“…Unlike other actinorhizal nodules, Frankia strains do not form vesicles to protect nitrogenase in Casuarina nodules, which may be linked to the abundance of Cgla2 in the cytosol (Fleming et al , ; Silvester et al , ). By contrast, a Glb has been found at low concentration in nodules of Alnus glutinosa , although it may be a truncated Glb of Frankia (Silvester et al , ). Interestingly, Pand1 is similar to Lbs in many critical aspects, including the kinetics for O 2 and CO binding (Kortt et al , ; Sturms et al , ) and the localization in the cytosol of nodule infected cells (Trinick et al , ).…”

Section: Globins In Symbiosismentioning

confidence: 99%

Plant hemoglobins: a journey from unicellular green algae to vascular plants

et al. 2020

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Globins (Glbs) are widely distributed in archaea, bacteria and eukaryotes. They can be classified into proteins with 2/2 or 3/3 a-helical folding around the heme cavity. Both types of Glbs occur in green algae, bryophytes and vascular plants. The Glbs of angiosperms have been more intensively studied, and several protein structures have been solved. They can be hexacoordinate or pentacoordinate, depending on whether a histidine is coordinating or not at the sixth position of the iron atom. The 3/3 Glbs of class 1 and the 2/2 Glbs (also called class 3 in plants) are present in all angiosperms, whereas the 3/3 Glbs of class 2 have been only found in early angiosperms and eudicots. The three Glb classes are expected to play different roles. Class 1 Glbs are involved in hypoxia responses and modulate NO concentration, which may explain their roles in plant morphogenesis, hormone signaling, cell fate determination, nutrient deficiency, nitrogen metabolism and plant-microorganism symbioses. Symbiotic Glbs derive from class 1 or class 2 Glbs and transport O 2 in nodules. The physiological roles of class 2 and class 3 Glbs are poorly defined but could involve O 2 and NO transport and/or metabolism, respectively. More research is warranted on these intriguing proteins to determine their non-redundant functions.

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“…This is thought to be mediated by long-distance signals transmitted in phloem from shoots to nodules, which ultimately affect nitrogenase or other key enzymes involved with C or N metabolism of N fixation (Valverde and Huss-Danell 2008). Lower nodule respiration reduces respiratory ATP production and increases pO 2 within vesicles, both of which serve to further reduce nitrogenase activity and N-fixation rates (Silvester et al 2008). Greenhouse experiments with A. incana demonstrate that nodule initiation and C partitioning to nodule growth are reduced by elevated ratios of N:P in growth solutions (Huss-Danell et al 1982, Wall et al 1998, Gentili and Huss-Danell 2003, but we are unaware of field experiments that have quantified N-induced downregulation of N fixation, nodule respiration, and nodule biomass.…”

Section: Fertilization Effects On N Fixation and Plant N:p Balancementioning

confidence: 99%

Ecosystem‐level consequences of symbiont partnerships in an N‐fixing shrub from interior Alaskan floodplains

Ruess

Anderson

McFarland

et al. 2013

Ecological Monographs

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In long-lived N-fixing plants, environmental conditions affecting plant growth and N demand vary at multiple temporal and spatial scales, and symbiont assemblages on a given host and patterns of allocation to nodule activities have been shown to vary according to environmental factors, suggesting that hosts may alter partner choice and manipulate symbiont assemblages based on shifting plant needs. This study assessed economic trade-offs among N-fixing symbionts of thin-leaf alder (Alnus tenuifolia) by examining whether alderFrankia associations change in response to the up-regulation (P fertilization) and downregulation (N-fertilization) of N-fixation activities, and whether these changes are associated with differences among Frankia partners in their relative C cost and/or N benefit to A. tenuifolia.Relative to control plots, alder in þP plots had significantly higher nodule biomass and Nfixation rates; these parameters were significantly lower in þN plots, translating to stand-level N inputs that were more than an order of magnitude greater in þP than þN plots. Nodule respiration and N-fixation rates were positively correlated, and analyses revealed that alder employs mechanisms to increase the efficiency of C use when N fixation is up-regulated. Of the eight Frankia OTUs (operational taxonomic units) identified, two were dominant, with significant differences in Frankia OTU composition across samples being explained by fertilization treatment. Dominant OTUs had similar up-and down-regulatory responses to treatments but differed in C costs of N fixation, while the most abundant sub-dominant failed to up-regulate N-fixation rates in þP plots. Differences among Frankia OTUs in traits relevant to plant performance may form the basis for host choice and explain successional shifts in alder-Frankia assemblages. We suggest that manipulation of Frankia assemblages is an adaptation for a species such as A. tenuifolia that maintains a high dependence on atmospheric N across radically different growth environments. Because of the strong effects of thin-leaf alder on soil N contents, it appears that host changes in C partitioning to nodule activities, including the physiological consequences of host specificity for Frankia assemblages, results in alder both driving and responding to environmental heterogeneity at small to large spatial scales.

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Oxygen Responses, Hemoglobin, And The Structure And Function Of Vesicles

Cited by 15 publications

References 112 publications

Comparative genomics of the nonlegume Parasponia reveals insights into evolution of nitrogen-fixing rhizobium symbioses

Comparative genomics of the nonlegume Parasponia reveals insights into evolution of nitrogen-fixing rhizobium symbioses

Plant hemoglobins: a journey from unicellular green algae to vascular plants

Ecosystem‐level consequences of symbiont partnerships in an N‐fixing shrub from interior Alaskan floodplains

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