Getting around the legume nodule: I. The structure of the peripheral zone in four nodule types

Guinel, Frédérique C.

doi:10.1139/b09-074

Cited by 63 publications

(85 citation statements)

References 92 publications

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“…A number of cell layers, including one or two layers of distributing, boundary and pericycle cells, separate the vascular bundle from the infected zone in soybean nodules (Guinel, 2009). Little is known about iron movement between the xylem and infected cells, both symplastic and apoplastic routes are postulated ( Figure 2 ).…”

Section: Iron Movement Within the Nodulementioning

confidence: 99%

Iron: an essential micronutrient for the legume-rhizobium symbiosis

Brear¹,

Day²,

Smith³

2013

Front. Plant Sci.

175

166

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Legumes, which develop a symbiosis with nitrogen-fixing bacteria, have an increased demand for iron. Iron is required for the synthesis of iron-containing proteins in the host, including the highly abundant leghemoglobin, and in bacteroids for nitrogenase and cytochromes of the electron transport chain. Deficiencies in iron can affect initiation and development of the nodule. Within root cells, iron is chelated with organic acids such as citrate and nicotianamine and distributed to other parts of the plant. Transport to the nitrogen-fixing bacteroids in infected cells of nodules is more complicated. Formation of the symbiosis results in bacteroids internalized within root cortical cells of the legume where they are surrounded by a plant-derived membrane termed the symbiosome membrane (SM). This membrane forms an interface that regulates nutrient supply to the bacteroid. Consequently, iron must cross this membrane before being supplied to the bacteroid. Iron is transported across the SM as both ferric and ferrous iron. However, uptake of Fe(II) by both the symbiosome and bacteroid is faster than Fe(III) uptake. Members of more than one protein family may be responsible for Fe(II) transport across the SM. The only Fe(II) transporter in nodules characterized to date is GmDMT1 (Glycine max divalent metal transporter 1), which is located on the SM in soybean. Like the root plasma membrane, the SM has ferric iron reductase activity. The protein responsible has not been identified but is predicted to reduce ferric iron accumulated in the symbiosome space prior to uptake by the bacteroid. With the recent publication of a number of legume genomes including Medicago truncatula and G. max, a large number of additional candidate transport proteins have been identified. Members of the NRAMP (natural resistance-associated macrophage protein), YSL (yellow stripe-like), VIT (vacuolar iron transporter), and ZIP (Zrt-, Irt-like protein) transport families show enhanced expression in nodules and are expected to play a role in the transport of iron and other metals across symbiotic membranes.

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Section: Iron Movement Within the Nodulementioning

confidence: 99%

Iron: an essential micronutrient for the legume-rhizobium symbiosis

Brear¹,

Day²,

Smith³

2013

Front. Plant Sci.

175

166

View full text Add to dashboard Cite

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“…More mature nodules exhibited additional branching of the vascular bundles with the distal areas losing GUS staining as the vascular bundles matured (Figure 5e,f). Figure 5g illustrates a near-median, sagittal [50] section of a nodule stained for GUS (arrow). The interior cells of the nodule are occupied by bacteroids.…”

Section: Nodulation In Response To Coinoculationmentioning

confidence: 99%

Bacillus simplex—A Little Known PGPB with Anti-Fungal Activity—Alters Pea Legume Root Architecture and Nodule Morphology When Coinoculated with Rhizobium leguminosarum bv. viciae

et al. 2013

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Two strains, 30N-5 and 30VD-1, identified as Bacillus simplex and B. subtilis, were isolated from the rhizospheres of two different plants, a Podocarpus and a palm, respectively, growing in the University of California, Los Angeles (UCLA) Mildred E. Mathias Botanical Garden. B. subtilis is a well-known plant-growth promoting bacterial species, but B. simplex is not. B. simplex 30N-5 was initially isolated on a nitrogen-free medium, but no evidence for nitrogen fixation was found. Nevertheless, pea OPEN ACCESSAgronomy 2013, 3 596 plants inoculated with B. simplex showed a change in root architecture due to the emergence of more lateral roots. When Pisum sativum carrying a DR5::GUSA construct, an indicator for auxin response, was inoculated with either B. simplex 30N-5 or its symbiont Rhizobium leguminosarum bv. viciae 128C53, GUS expression in the roots was increased over the uninoculated controls. Moreover, when pea roots were coinoculated with either B. simplex 30N-5 or B. subtilis 30VD-1 and R. leguminosarum bv. viciae 128C53, the nodules were larger, clustered, and developed more highly branched vascular bundles. Besides producing siderophores and solubilizing phosphate, the two Bacillus spp., especially strain 30VD-1, exhibited anti-fungal activity towards Fusarium. Our data show that combining nodulating, nitrogen-fixing rhizobia with growth-promoting bacteria enhances plant development and strongly supports a coinoculation strategy to improve nitrogen fixation, increase biomass, and establish greater resistance to fungal disease.

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“…All five replicates indicated an AON control circuit, as the delayed inoculated root system always had lower numbers of nodules. [14] In separate experiments, KNO 3 was supplied to pongamia seedlings inoculated with B. japonicum strain CB1809. Plants were examined after 8 weeks cultivation and significant reduction (90 %) in nodule number per plant was observed with 10 mM KNO 3 supplied on alternate days.…”

Section: Autoregulation Of Nodulation (Aon) In Pongamiamentioning

confidence: 99%

Nodulation in the Legume Biofuel Feedstock Tree Pongamia pinnata

2013

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The legume tree Pongamia pinnata (also called Millettia pinnata) is gaining importance as a biofuel feedstock tree because of the abundant annual production of oil-rich seeds, adaptation to a wide range of geoclimatic conditions and significant resistance to abiotic stress, such as water-deficit, salinity and acidity of soils. The major defining benefit of using pongamia as a biofuel feedstock is that it is a legume, enabling biological nitrogen fixation through symbiosis with soil bacteria, collectively called rhizobia, which results in root nodulation. Here, we report preliminary data, (i) indicating the range of rhizobia that can form nodules on pongamia, (ii) demonstrating the measurement of nitrogen fixation activity of pongamia nodules via the classical acetylene reduction assay, (iii) illustrating nodule morphology and development and (iv) demonstrating aspects of nodule regulation by external nitrate as well as internal autoregulation of nodulation. We note that in pongamia most nodulation-related characteristics are similar to those found in other annual crop legumes such as soybean.

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Getting around the legume nodule: I. The structure of the peripheral zone in four nodule types

Cited by 63 publications

References 92 publications

Iron: an essential micronutrient for the legume-rhizobium symbiosis

Iron: an essential micronutrient for the legume-rhizobium symbiosis

Bacillus simplex—A Little Known PGPB with Anti-Fungal Activity—Alters Pea Legume Root Architecture and Nodule Morphology When Coinoculated with Rhizobium leguminosarum bv. viciae

Nodulation in the Legume Biofuel Feedstock Tree Pongamia pinnata

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