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This review discusses the role arbuscular mycorrhizal fungi play in the regulation of plant nutrient transporter genes. Many plant nutrient transporter genes appear to be transcriptionally regulated by a feed-back mechanism that reduces their expression when the plant reaches an optimal level of nutrition. Their down-regulation in mycorrhizal roots, therefore, would be predicted as a result of sym
This study of functional diversity considers symbiotic associations between two plant species, Medicago truncatula and Lycopersicon esculentum, and seven species of arbuscular mycorrhizal fungi (AMF). The objective was to integrate physiological analyses with molecular techniques to test whether functional diversity between AMF species is not only apparent at the level of mycorrhiza formation, pla
The influence of arbuscular mycorrhizal fungi (AMF) on the expression of plant nutrient transporters was studied using a relative, quantitative reverse-transcription polymerase chain-reaction (RQRT-PCR) technique. Reverse-transcribed 18S rRNA was used to standardize the treatments. The technique had high reproducibility and reflected trends in gene expression as observed by Northern blotting. Usin
Two rapid and simple in planta transformation methods have been developed for the model legume Medicago truncatula. The first approach is based on a method developed for transformation of Arabidopsis thaliana and involves infiltration of flowering plants with a suspension of Agrobacterium. The second method involves infiltration of young seedlings with Agrobacterium. I
Mt4 is a cDNA representing a phosphate-starvation-inducible gene from Medicago truncatula that is down-regulated in roots in response to inorganic phosphate (Pi) fertilization and colonization by arbuscular mycorrhizal fungi. Split-root experiments revealed that the expression of the Mt4 gene in M. truncatula roots is down-regulated systemically by both Pi fertilization and colonization by arbuscu
A cDNA clone (Gv1) was isolated from a Medicago truncatula/Glomus versiforme root cDNA library by a differential screening technique. Gv1 represents a full-length G. versiforme mRNA encoding a 99-amino-acid polypeptide. This shares regions of identity with HMP1, a non-histone, cruciform DNA-binding protein from Ustilago maydis. Northern blot analysis indicated that Gv1 transcripts were present in
A cDNA clone (Mt4) was isolated as a result of a differential screen to identify genes showing altered expression during the interaction between Medicago truncatula and the vesicular-arbuscular mycorrhizal (VAM) fungus Glomus versiforme. Mt4 represents a M. truncatula, mRNA that contains numerous short open reading frames, the two longest of which are predicted to encode polypeptides of 51 amino a
Spores of Frankia strain HFPCcl3 nodulated Casuarina equisetifolia after passage through the digestive tracts of captive parakeets (Melopsittacus undulatus). Parakeets excreted infectious fecal material from 6 to 72 h after ingesting food inoculated with Frankia spores. Air desiccation of spore-containing fecal material reduced its infectious capacity by approximately 90%. Hyphal filaments of this
The ability of Hawaiian volcanic soils to nodulate actinorhizal Myrica cerifera, Casuarina equisetifolia, and Alnus glutinosa was determined using a host-plant bioassay. Myrica-nodulating Frankia occurred in five volcanic deposits with depositional ages ranging from 20 to 162 years before present. The oldest deposit had a mean estimated nodulation capacity from 450 to 1200 times greater than those
Frankia strains grew more and had greater nodulation capacities after air-desiccation when exposed to sugar osmotica prior to dying. Exposure to 200 mm sucrose, maltose or melibiose resulted in an increase in the cellular concentration of the disaccharide trehalose. The cellular trehalose concentration of Frankia strain HFPArI3 from Alnus rubra was positively, linearly correlated with its growth a
Optimization of the in vitro sporulation of Frankia is a prerequisite for the development of spore preparations as a practical inoculum for actinorhizal plants. The in vitro sporulation of Frankia strain HFPCcI3 previously isolated from Casuarina cunninghamiana was increased from 0 to 12 million spores per millilitre of culture medium when nitrogen and phosphorus were excluded from a defined nutri
The in vitro growth and sporulation of Frankia isolate HFPCcI3, a nitrogen‐fixing symbiont of Casuarina, was inhibited by both the toxic and osmotic effects of sodium chloride. This was demonstrated by comparing HFPCcI3 halotolerance with its tolerance to metabolically neutral melibiose osmoticum at sodium chloride and melibiose concentrations from 0 to 500 mmol L‐1. The osmotolerance of this stra
The soil bacterium Frankia of the Actinomycetales, capable of forming N2-fixing symbiotic root nodules on a diverse array of actinorhizal plants, has several morphological forms when grown in pure culture. Fresh hydrated preparations of whole cells, hyphae, and spores were all infective on seedlings of Casuarina at different dilutions. Desiccated hyphae showed no infection capacity, while desiccat
Varying processing conditions can strongly affect the microstructure of mayonnaise, opening up new applications for the creation of products tailored to meet different consumer preferences. The aim of the study was to evaluate the effect of emulsification intensity on sensory and instrumental characteristics of full-fat mayonnaise. Mayonnaise, based on a standard recipe, was processed at low and h
Coalescence during emulsification has a significant effect on the outcome of the process, especially for the high volume fractions of disperse phase common in food and pharmaceutical processing. Controlling emulsification requires that the extent of coalescence during different conditions can be quantified. The step-down technique is the most commonly used method for measuring coalescence frequenc
