Down Regulation of Nodule Sucrose Synthase by Mutation and Antisense

Gordon, A. R.; Skøt, Leif; Webb, K. Judith; Minchin, F. R.; James, Caron; Wang, T. L.; Hedley, C. L.; Craig, Josephine; Smith, Alison M.

doi:10.1007/978-94-011-5159-7_288

Cited by 4 publications

(4 citation statements)

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“…In addition to SucS, apoplastic invertases are able to degrade sucrose (Morell and Copeland 1984), but SucS seems to be primarily responsible for sucrose degradation in mature nodules (Kouchi et al 1988;Anthon and Emmerich 1990). This was con®rmed by Wang and Hedley (1993), as well as by Gordon et al (1998), who reported that Pisum sativum and Lotus japonicus plants with a reduced level of SucS enzymes were severely impaired in growth on nitrogen-free medium.…”

Section: Introductionmentioning

confidence: 80%

Genomic organization and expression properties of the MtSucS1 gene, which encodes a nodule-enhanced sucrose synthase in the model legume Medicago truncatula

Hohnjec¹,

Becker²,

Pühler³

et al. 1999

Mol Gen Genet

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We have isolated and sequenced a sucrose synthase (SucS) cDNA from the model legume Medicago truncatula. This cDNA (MtSucS1) contains an ORF of 2418 bp, coding for a protein of 805 amino acids with a molecular mass of 92.29 kDa. The deduced amino acid sequence shows significant homology to other plant sucrose synthases, in particular to the nodule-enhanced sucrose synthases from pea and broad bean. Northern analysis revealed that the corresponding gene shows a ten-fold higher expression level in root nodules than in uninfected root, stem and leaf tissues. SucS protein was detected in root nodules from a variety of legumes, including M. truncatula. Whereas only one SucS isoform was detectable in root nodules, an additional sucrose synthase of slightly larger molecular weight was present in uninfected root, stem and flower tissues of M. truncatula. From our expression and sequence data we infer that the MtSucS1 gene encodes a nodule-enhanced sucrose synthase in M. truncatula. Southern hybridization data indicate that MtSucS1 is a single-copy gene. An analysis of a genomic MtSucS1 sequence revealed that the gene consists of 14 exons with the start codon being located on exon II. As is common for SucS genes, the MtSucS1 gene contains a large intron of 747 bp in the 5' untranslated region. The transcriptional start of MtSucS1 was mapped and putative regulatory elements in the MtSucS1 promoter were identified.

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Section: Introductionmentioning

confidence: 80%

Genomic organization and expression properties of the MtSucS1 gene, which encodes a nodule-enhanced sucrose synthase in the model legume Medicago truncatula

Hohnjec¹,

Becker²,

Pühler³

et al. 1999

Mol Gen Genet

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“…Sucrose is the primary carbon resource for energy supply and carbon skeletons for SNF and is supplied to legume nodules by transportation from the shoots (Gordon et al, 1998). However, sucrose is not used directly as a substrate by isolated nitrogen-fixing bacteroids to support nitrogenase activity, as demonstrated in the cases of soybean (Stovall and Cole, 1978), garden pea (Glenn and Dilworth, 1981), lupin (Tomaszewska et al, 1991), and alfalfa (Miller et al, 1988).…”

Section: Overview Of Metabolism and Regulation In The Host Plantmentioning

confidence: 99%

“…SS performs a reversible UDP-dependent cleavage of sucrose into UDP-glucose (UDP-Glc) and fructose (Akazawa and Okamoto, 1980). SS activity is reduced in the SNF-defective mutant, rug4 , of P. sativum , indicating that SS plays an important role in nodule functions (Gordon et al, 1998, 1999). Moreover, overexpressing the antisense of MtSucS1 (encoding enzyme SS) in M. truncatula impaired the plant growth and nodulation in the MtSucS1 -reduced nodules, and the contents of amino acids and their derivatives were also found to be reduced, which suggest SS is a crucial player in the establishment and maintenance of an efficient SNF process (Baier et al, 2007).…”

Section: Overview Of Metabolism and Regulation In The Host Plantmentioning

confidence: 99%

Interaction and Regulation of Carbon, Nitrogen, and Phosphorus Metabolisms in Root Nodules of Legumes

et al. 2018

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Members of the plant family Leguminosae (Fabaceae) are unique in that they have evolved a symbiotic relationship with rhizobia (a group of soil bacteria that can fix atmospheric nitrogen). Rhizobia infect and form root nodules on their specific host plants before differentiating into bacteroids, the symbiotic form of rhizobia. This complex relationship involves the supply of C4-dicarboxylate and phosphate by the host plants to the microsymbionts that utilize them in the energy-intensive process of fixing atmospheric nitrogen into ammonium, which is in turn made available to the host plants as a source of nitrogen, a macronutrient for growth. Although nitrogen-fixing bacteroids are no longer growing, they are metabolically active. The symbiotic process is complex and tightly regulated by both the host plants and the bacteroids. The metabolic pathways of carbon, nitrogen, and phosphate are heavily regulated in the host plants, as they need to strike a fine balance between satisfying their own needs as well as those of the microsymbionts. A network of transporters for the various metabolites are responsible for the trafficking of these essential molecules between the two partners through the symbiosome membrane (plant-derived membrane surrounding the bacteroid), and these are in turn regulated by various transcription factors that control their expressions under different environmental conditions. Understanding this complex process of symbiotic nitrogen fixation is vital in promoting sustainable agriculture and enhancing soil fertility.

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“…Nodule nitrogen fixation depends on the photosynthate in the form of sucrose delivered from the phloem (Gordon et al 1998). Once in the nodule, sucrose can be cleaved by either sucrose synthase (SS; EC 2.4.1.13) or alkaline invertase (AI; EC 3.2.1.26).…”

Section: Introductionmentioning

confidence: 99%

Nitrogen fixation is synchronized with carbon metabolism inLotus japonicusandMedicago truncatulanodules under salt stress

López

Lluch

2008

Journal of Plant Interactions

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In the present work, the response to NaCl applied at the vegetative stage to Medicago truncatula and Lotus japonicus has been evaluated in order to ascertain whether the effect of salt stress on nitrogen fixation is due to a limitation on nodular carbon metabolism. Results show maximum sucrose synthase (SS) and alkaline invertase (AI) activities were obtained at the vegetative stage, when maximum nitrogenase activity was detected in both species. SS activity decreased with the salt treatment, providing evidence of the regulatory role of this enzyme for the carbon supply to the bacteroids. Phosphoenolpyruvate carboxylase (PEPC) and malate dehydrogenase (MDH) activities could account for higher nitrogen fixation efficiency detected in L. japonicus nodules and isocitrate dehydrogenase (ICDH) activity compensated for the carbon limitations that occur under salt stress. These results support that nitrogenase inhibition in nodules experiencing salt stress is doubt to a carbon flux shortage, as result of carbon metabolism enzymes activities down-regulation.

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Down Regulation of Nodule Sucrose Synthase by Mutation and Antisense

Cited by 4 publications

References 1 publication

Genomic organization and expression properties of the MtSucS1 gene, which encodes a nodule-enhanced sucrose synthase in the model legume Medicago truncatula

Genomic organization and expression properties of the MtSucS1 gene, which encodes a nodule-enhanced sucrose synthase in the model legume Medicago truncatula

Interaction and Regulation of Carbon, Nitrogen, and Phosphorus Metabolisms in Root Nodules of Legumes

Nitrogen fixation is synchronized with carbon metabolism inLotus japonicusandMedicago truncatulanodules under salt stress

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