Symbiotic nitrogen fixation research in the postgenomics era

Colebatch, Gillian; Trevaskis, Ben; Udvardi, Michael K.

doi:10.1046/j.0028-646x.2001.00304.x

Cited by 42 publications

(18 citation statements)

References 30 publications

(33 reference statements)

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“…The phytochemicals present in the root exudates of plants mediate several types of communication processes in the rhizosphere such as root-root, rootmicrobe and root-insect interactions (Walker et al 2003a;Bais et al 2004), and some of these interactions, such as the legume-rhizobium symbiosis, are of extreme agricultural importance (Colebatch et al 2002). Despite the importance of root exudation of phytochemicals to agriculture and ecology, the genes and networks that control this process have not been studied; and in fact classical knowledge about root exudation regards this occurrence as a passive process controlled by the concentration gradient of compounds (Phillips et al 2004).…”

Section: Introductionmentioning

confidence: 99%

Effect of transporters on the secretion of phytochemicals by the roots of Arabidopsis thaliana

Loyola‐Vargas

Broeckling

Badri

et al. 2006

Planta

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Root exudation, the process by which plants secrete compounds into the soil, is becoming accepted as a communicative process that determines organismal interactions in the rhizosphere. However, the mechanistic processes involved in the root exudation of phytochemicals have not been elucidated; traditionally, exudation has been regarded as a passive process. There is evidence that transporters in plants (and other organisms) have been involved in the movement of chemicals across different membranes. Here, we describe the involvement of different transporters in root exudation of phytochemicals by employing a pharmacological approach. We used a range of concentrations of several compounds known to inhibit different transporters, including potassium cyanide, orthovanadate, quinidine, glibenclamide, nifedipine and verapamil, to examine the effects of transporter inhibition on root exudation profiles in Arabidopsis. Generally, the exudation profile of phenolic compounds in 18-day-old plants shows more than 15 major phytochemicals. In contrast, the inhibitors listed above caused differences in the secretion of specific compounds. For instance, nifedipine and verapamil completely inhibited the exudation of the phytochemicals with molecular masses of 142 and 294, respectively. These results highlight that root exudation of phytochemicals is an active process controlled at the biochemical level and that different transporters may be involved in this root-specific mechanism.

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Section: Introductionmentioning

confidence: 99%

Effect of transporters on the secretion of phytochemicals by the roots of Arabidopsis thaliana

Loyola‐Vargas

Broeckling

Badri

et al. 2006

Planta

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“…The complete genome of S. meliloti has been annotated; however, the function of more than 40% of genes remains unknown (3,4). In the past decade, numerous efforts have been directed toward understanding gene function (functional genomics) and the mechanisms by which symbiosis and nitrogen fixation occur (5)(6)(7)(8). Our research focuses on the study of genes in S. meliloti that are hypothesized to participate in lipid biosynthesis.…”

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confidence: 99%

A shotgun lipidomics approach in Sinorhizobium meliloti as a tool in functional genomics

Basconcillo

Zaheer

Finan

et al. 2009

Journal of Lipid Research

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A shotgun lipidomics approach that allowed the analysis of eight lipid classes directly from crude extracts of the soil bacterium Sinorhizobium meliloti is presented. New MS-MS transitions are reported for the analysis of monomethylphosphatidylethanolamines, dimethylphosphatidylethanolamines, and three bacterial non-phosphorus-containing lipid classes [sulfoquinovosyldiacylglycerols, ornithines, and diacylglyceryl-(N,N,N-trimethyl)-homoserines]. Unique MS-MS transitions allowed the analysis of isomeric species from various lipid classes without chromatography. Analyses required small sample amounts and minimal preparation; thus, this methodology has excellent potential to be used as a screening tool for the analysis of large numbers of samples in functional genomics studies. FA distributions within lipid classes of S. meliloti are described for the first time, and the relative positions of fatty acyl substituents (sn-1, sn-2) in phospholipids are presented. FA distributions in diacylglyceryl-(N, N,N-trimethyl)-homoserines were identical to those of phospholipids, indicating a common biosynthetic origin for these lipids. The method was applied to the analysis of mutants deficient in the PhoB regulator protein. Increased lipid cyclopropanation was observed in PhoB-deficient mutants under P i starvation.-Basconcillo, L. S., R. Zaheer, T. M. Finan, and B. E. McCarry. A shotgun lipidomics approach in Sinorhizobium meliloti as a tool in functional genomics.

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“…Root secretions, or root exudates, help roots penetrate the soil (Iijima et al, 2003) and orchestrate rhizosphere interactions, including symbiotic, pathogenic, and allelopathic interactions. Hence, exudates play a central role in plant growth in natural habitats (Colebatch et al, 2002;Walker et al, 2003;Bais et al, 2004). Root exudates are composed of both low and high M r components, including an array of primary and secondary metabolites, proteins, and peptides (Bais et al, 2006;Weisskopf et al, 2006).…”

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confidence: 99%

Altered Profile of Secondary Metabolites in the Root Exudates of Arabidopsis ATP-Binding Cassette Transporter Mutants

et al. 2007

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Following recent indirect evidence suggesting a role for ATP-binding cassette (ABC) transporters in root exudation of phytochemicals, we identified 25 ABC transporter genes highly expressed in the root cells most likely to be involved in secretion processes. Of these 25 genes, we also selected six full-length ABC transporters and a half-size transporter for in-depth molecular and biochemical analyses. We compared the exuded root phytochemical profiles of these seven ABC transporter mutants to those of the wild type. There were three nonpolar phytochemicals missing in various ABC transporter mutants compared to the wild type when the samples were analyzed by high-performance liquid chromatography-mass spectrometry. These data suggest that more than one ABC transporter can be involved in the secretion of a given phytochemical and that a transporter can be involved in the secretion of more than one secondary metabolite. The primary and secondary metabolites present in the root exudates of the mutants were also analyzed by gas chromatography-mass spectrometry, which allowed for the identification of groups of compounds differentially found in some of the mutants compared to the wild type. For instance, the mutant Atpdr6 secreted a lower level of organic acids and Atmrp2 secreted a higher level of amino acids as compared to the wild type. We conclude that the release of phytochemicals by roots is partially controlled by ABC transporters.

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Symbiotic nitrogen fixation research in the postgenomics era

Cited by 42 publications

References 30 publications

Effect of transporters on the secretion of phytochemicals by the roots of Arabidopsis thaliana

Effect of transporters on the secretion of phytochemicals by the roots of Arabidopsis thaliana

A shotgun lipidomics approach in Sinorhizobium meliloti as a tool in functional genomics

Altered Profile of Secondary Metabolites in the Root Exudates of Arabidopsis ATP-Binding Cassette Transporter Mutants

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