The Role of Peribacteroid Membrane in Legume Root Nodules

Abstract Legumes utilize a shoot-mediated signaling system to maintain a mutualistic relationship with nitrogen-fixing bacteria in root nodules. In Lotus japonicus, shoot-to-root transfer of microRNA miR2111 that targets TOO MUCH LOVE, a nodulation suppressor in roots, has been proposed to explain the mechanism underlying nodulation control from shoots. However, the role of shoot-accumulating miR2111s for the systemic regulation of nodulation was not clearly shown. Here, we find L. japonicus has seven miR2111 loci, including those mapped through RNA-seq. MIR2111-5 expression in leaves is the highest among miR2111 loci and repressed after rhizobial infection depending on a shoot-acting HYPERNODULATION ABERRANT ROOT FORMATION1 (HAR1) receptor. MIR2111-5 knockout mutants show significantly decreased nodule numbers and miR2111 levels. Furthermore, grafting experiments using transformants demonstrate scions with altered miR2111 levels influence nodule numbers in rootstocks in a dose-dependent manner. Therefore, miR2111 accumulation in leaves through MIR2111-5 expression is required for HAR1-dependent systemic optimization of nodule number.

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Phytosulfokine Is Involved in Positive Regulation of Lotus japonicus Nodulation

Molecular Plant-Microbe Interactions ◽

10.1094/mpmi-02-15-0032-r ◽

2015 ◽

Vol 28 (8) ◽

pp. 847-855 ◽

Cited By ~ 13

Author(s):

Chao Wang ◽

Haixiang Yu ◽

Zhongming Zhang ◽

Liangliang Yu ◽

Xiaoshu Xu ◽

...

Keyword(s):

Potential Role ◽

Early Stage ◽

Root Nodules ◽

Lotus Japonicus ◽

Positive Regulation ◽

Transgenic Hairy Roots ◽

Exogenous Addition ◽

Nodule Initiation ◽

Spontaneous Nodules

Phytosulfokine (PSK) is a tyrosine-sulfated peptide that is widely distributed in plants, participating in cell proliferation, differentiation, and innate immunity. The potential role of PSK in nodulation in legumes has not been reported. In this work, five PSK precursor genes were identified in Lotus japonicas, designated as LjPSK1 to LjPSK5. Three of them (LjPSK1, LjPSK4, and LjPSK5) were found to be expressed in nitrogen-fixing root nodules. LjPSK1 and LjPSK4 were not induced at the early stage of nodulation. Interestingly, while the expression of LjPSK4 was also found in spontaneous nodules without rhizobial colonization, LjPSK1 was not induced in these pseudo nodules. Promoter-β-glucuronidase analysis revealed that LjPSK1 was highly expressed in enlarged symbiotic cells of nodules. Exogenous addition of 1 μM synthetic PSK peptide resulted in increased nodule numbers per plant. Consistently, the number of mature nodules but not the events of rhizobial infection and nodule initiation was increased by overexpressing LjPSK1 in transgenic hairy roots, in which the expression of jasmonate-responsive genes was found to be repressed. These results suggest that PSK is a new peptide signal that regulates nodulation in legumes, probably through cross-talking with other phytohormones.

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The role of Bradyrhizobium japonicum nitric oxide reductase in nitric oxide detoxification in soya bean root nodules

Biochemical Society Transactions ◽

10.1042/bst0340195 ◽

2006 ◽

Vol 34 (1) ◽

pp. 195-196 ◽

Cited By ~ 17

Author(s):

G.E. Meakin ◽

B.J.N. Jepson ◽

D.J. Richardson ◽

E.J. Bedmar ◽

M.J. Delgado

Keyword(s):

Nitric Oxide ◽

Bradyrhizobium Japonicum ◽

Root Nodules ◽

Soya Bean ◽

Nitric Oxide Reductase ◽

Bean Root ◽

Detoxification Systems ◽

Nitric Oxide Detoxification

The identification of nitric oxide-bound leghaemoglobin within soya bean nodules has led to the question of how Bradyrhizobium japonicum bacteroids overcome the toxicity of this nitric oxide. It has previously been shown that one candidate for nitric oxide detoxification, the respiratory nitric oxide reductase, is expressed in soya bean nodules from plants supplied with nitrate [Mesa, de Dios Alché, Bedmar and Delgado (2004) Physiol. Plant. 120, 205–211]. In this paper, the role of this enzyme in nitric oxide detoxification is assessed and discussion is provided on other possible B. japonicum nitric oxide detoxification systems.

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Functional identification of ATP-driven Ca2+ pump in the peribacteroid membrane of broad bean root nodules

FEBS Letters ◽

10.1016/s0014-5793(99)00262-8 ◽

1999 ◽

Vol 447 (1) ◽

pp. 49-52 ◽

Cited By ~ 17

Author(s):

Igor M. Andreev ◽

Pavel N. Dubrovo ◽

Valeria V. Krylova ◽

Stanislav F. Izmailov

Keyword(s):

Broad Bean ◽

Root Nodules ◽

Functional Identification ◽

Peribacteroid Membrane ◽

Bean Root

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Identification with Proteomics of Novel Proteins Associated with the Peribacteroid Membrane of Soybean Root Nodules

Molecular Plant-Microbe Interactions ◽

10.1094/mpmi.2000.13.3.325 ◽

2000 ◽

Vol 13 (3) ◽

pp. 325-333 ◽

Cited By ~ 87

Author(s):

S. Panter ◽

R. Thomson ◽

G. de Bruxelles ◽

D. Laver ◽

B. Trevaskis ◽

...

Keyword(s):

Protein Translocation ◽

Sequence Data ◽

Root Nodules ◽

Integral Membrane Proteins ◽

Nitrogen Fixing ◽

Peribacteroid Membrane ◽

Novel Proteins ◽

Cytoplasmic Proteins ◽

Molecular Machinery ◽

Specific Proteins

Soybean peribacteroid membrane (PBM) proteins were isolated from nitrogen-fixing root nodules and subjected to N-terminal sequencing. Sequence data from 17 putative PBM proteins were obtained. Six of these proteins are homologous to proteins of known function. These include three chaperones (HSP60, BiP [HSP70], and PDI) and two proteases (a serine and a thiol protease), all of which are involved in some aspect of protein processing in plants. The PBM homologs of these proteins may play roles in protein translocation, folding, maturation, or degradation in symbiosomes. Two proteins are homologous to known, nodule-specific proteins from soybean, nodulin 53b and nodulin 26B. Although the function of these nodulins is unknown, nodulin 53b has independently been shown to be associated with the PBM. All of the eight proteins with identifiable homologs are likely to be peripheral rather than integral membrane proteins. Possible reasons for this apparent bias are discussed. The identification of homologs of HSP70 and HSP60 associated with the PBM is the first evidence that the molecular machinery for co- or post-translational import of cytoplasmic proteins is present in symbiosomes. This has important implications for the biogenesis of this unique, nitrogen-fixing organelle.

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