Evolution of Hominin Detoxification: Neanderthal and Modern Human Ah Receptor Respond Similarly to TCDD.

In studies of hominin adaptations to fire use, the role of the aryl hydrocarbon receptor (AHR) in the evolution of detoxification has been highlighted, including statements that the modern human AHR confers a significantly better capacity to deal with toxic smoke components than the Neanderthal AHR. To evaluate this, we compared the AHR-controlled induction of cytochrome P4501A1 (CYP1A1) mRNA in HeLa human cervix epithelial adenocarcinoma cells transfected with an Altai-Neanderthal or a modern human reference AHR expression construct, and exposed to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). We compared the complete AHR mRNA sequences including the untranslated regions (UTRs), maintaining the original codon usage.

The Medicago truncatula nodule identity gene MtNOOT1 is required for coordinated apical-basal development of the root.

Background: Legumes can utilize atmospheric nitrogen by hosting nitrogen-fixing bacteria in special lateral root organs, called nodules. Legume nodules have a unique ontology, despite similarities in the gene networks controlling nodule and lateral root development. It has been shown that Medicago truncatula NODULE ROOT1 (MtNOOT1) is required for the maintenance of nodule identity, preventing the conversion to lateral root development.

Cis-regulatory PLETHORA promoter elements directing root and nodule expression are conserved between Arabidopsis thaliana and Medicago truncatula.

Nodules are unique organs formed on roots of legumes by soil-borne bacteria, collectively known as rhizobium. Recently, we have shown that orthologs of the AINTEGUMENTA-like (AIL) AP2 transcription factors PLETHORA (PLT) 1 to 4, that redundantly regulate Arabidopsis thaliana root development are involved in root and nodule growth in Medicago truncatula. Hence, it is conceivable that rhizobium has co-opted these genes for nodule development.

Root developmental programs shape the Medicago truncatula nodule meristem.

Nodules on the roots of legume plants host nitrogen-fixing Rhizobium bacteria. Several lines of evidence indicate that nodules are evolutionarily related to roots. We determined whether developmental control of the Medicago truncatula nodule meristem bears resemblance to that in root meristems through analyses of root meristem-expressed PLETHORA genes.

Rhizobium Lipo-chitooligosaccharide Signaling Triggers Accumulation of Cytokinins in Medicago truncatula Roots.

Legume rhizobium symbiosis is initiated upon perception of bacterial secreted lipo-chitooligosaccharides (LCOs). Perception of these signals by the plant initiates a signaling cascade that leads to nodule formation. Several studies have implicated a function for cytokinin in this process.

Fate map of Medicago truncatula root nodules.

Legume root nodules are induced by N-fixing rhizobium bacteria that are hosted in an intracellular manner. These nodules are formed by reprogramming differentiated root cells. The model legume Medicago truncatula forms indeterminate nodules with a meristem at their apex.

Assessment of technological options and economical feasibility for cyanophycin biopolymer and high-value amino acid production.

Major transitions can be expected within the next few decades aiming at the reduction of pollution and global warming and at energy saving measures. For these purposes, new sustainable biorefinery concepts will be needed that will replace the traditional mineral oil-based synthesis of specialty and bulk chemicals. An important group of these chemicals are those that comprise N-functionalities.

Medicago truncatula ENOD40-1 and ENOD40-2 are both involved in nodule initiation and bacteroid development.

The establishment of a nitrogen-fixing root nodule on legumes requires the induction of mitotic activity of cortical cells leading to the formation of the nodule primordium and the infection process by which the bacteria enter this primordium. Several genes are up-regulated during these processes, among them ENOD40. Here it is shown, by using gene-specific knock-down of the two Medicago truncatula ENOD40 genes, that both genes are involved in nodule initiation.

ENOD40 affects elongation growth in tobacco Bright Yellow-2 cells by alteration of ethylene biosynthesis kinetics.

Plant developmental processes are controlled by co-ordinated action of phytohormones and plant genes encoding components of developmental response pathways. ENOD40 was identified as a candidate for such a plant factor with a regulatory role during nodulation. Although its mode of action is poorly understood, several lines of evidence suggest interaction with phytohormone response pathways.

Formation of organelle-like N2-fixing symbiosomes in legume root nodules is controlled by DMI2.

In most legume nodules, the N2-fixing rhizobia are present as organelle-like structures inside their host cells. These structures, named symbiosomes, contain one or a few rhizobia surrounded by a plant membrane. Symbiosome formation requires the release of bacteria from cell-wall-bound infection threads.

Reduction of cell size induced by enod40 in Arabidopsis thaliana.

An extensive analysis of organ and cell size was performed in three different Arabidopsis lines transformed with the early nodulin gene enod40 under control of the CaMV35S promoter. All three transgenic lines presented a significant decrease in the mean size of both epidermal internode and leaf mesophyll cells. Flow cytometric and image analysis of enod40-transfected protoplasts prepared from wild-type Arabidopsis cell suspensions showed that transient expression of the gene resulted in reduced forward light scattering (a factor correlated with particle size) and cell size.

RNA interference in Agrobacterium rhizogenes-transformed roots of Arabidopsis and Medicago truncatula.

RNA interference (RNAi) is a powerful reverse genetic tool to study gene function. The data presented here show that Agrobacterium rhizogenes-mediated RNAi is a fast and effective tool to study genes involved in root biology. The Arabidopsis gene KOJAK, involved in root hair development, was efficiently knocked down.

Identification and characterization of a Zea mays line carrying a transposon-tagged ENOD40.

In Zea mays, two ENOD40 homologous were identified that show only 30% of sequence homology to each other. We identified line e40-mum1 carrying a Mu transposon inserted in ZmENOD40-1, the maize gene that has the highest homology to leguminous ENOD40. The insertion causes a dramatic reduction of the ZmENOD40-1 transcript level.

Expression of ENOD40 during tomato plant development.

In legumes, ENOD40 expression is increased upon interaction of plants with rhizobia. Little is known of the expression pattern of ENOD40 during other stages of the plant life cycle. Studies of ENOD40 expression in non-legume development may give an indication of the function of the gene.