Improving growth, flower yield, and water relations of snapdragon (Antirhinum majus L.) plants grown under well-watered and water-stress conditions using arbuscular mycorrhizal fungi

The influence of arbuscular mycorrhizal (AM) fungus Glomus deserticola (Trappe and John) on plant growth, nutrition, flower yield, water relations, chlorophyll (Chl) contents and water-use efficiency (WUE) of snapdragon (Antirhinum majus cv. butterfly) plants were studied in potted culture under well-watered (WW) and water-stress (WS) conditions. The imposed water stress condition significantly reduced all growth parameters, nutrient contents, flower yield, water relations, and Chl pigment content and increased the electrolyte leakage of the plants comparing to those of nonstressed plants. Regardless of the WS level, the mycorrhizal snapdragon plants had significantly higher shoot and root dry mass (DM), WUE, flower yield, nutrient (P, N, K, Mg, and Ca) and Chl contents than those nonmycorrhizal plants grown both under WW or WS conditions. Under WS conditions, the AM colonization had greatly improved the leaf water potential (??_w), leaf relative water content (RWC) and reduced the leaf electrolyte leakage (EL) of the plants. Although the WS conditions had markedly increased the proline content of the leaves, this increase was significantly higher in nonmycorrhizal than in mycorrhizal plants. This suggests that AM colonization enhances the host plant WS tolerance. Values of benefit and potential dry matter for AM-root associations were highest when plants were stressed and reduced under WW conditions. As a result, the snapdragon plants showed a high degree of dependency on AM fungi which improve plant growth, flower yield, water relations particularly under WS conditions, and these improvements were increased as WS level had increased. This study confirms that AM colonization can mitigate the deleterious effect of water stress on growth and flower yield of the snapdragon ornamental plant.     

New developments in developmental biology

A report on the 15th International Society of Developmental Biologists Congress, Sydney, Australia, 3-7 September 2005.     

Bioconversion of poultry wastes. I--Factors influencing the assay and productivity of crude uricase by three uricolytic filamentous fungi

The optimum temperature for biomass yield and uricase production by uricolytic fungi, Aspergillus terreus, A. flavus and Trichoderma sp. was at 30 degrees C. The time required for maximum production of uricase and biomass yield was 4 days for two Aspergillus species and 6 days for Trichoderma sp. The optimum pH was at 6.4 for A. terreus and pH 6.6 for A. flavus and Trichoderma sp. The maximum fungal biomass yield was achieved in medium supplemented with 4% poultry waste. The best carbon sources for the production of uricase and mycelia yield were glycerol, sucrose and maltose by A. terreus, A. flavus and Trichoderma sp., respectively. Uric acid was found to be the best nitrogen source for production and activity of uricase by the three tested fungi. The addition of some vitamins to the culture media increased the maximum biomass yield of all the isolates, although no significantly increased uricase production was found.     

Complete nucleotide sequences of bovine alpha S2- and beta-casein cDNAs: comparisons with related sequences in other species

The nucleotide sequences corresponding to bovine alpha S2- and beta- casein mRNAs have been determined by cDNA analysis. Both sequences appear to be complete at their 5' ends. The nucleotide sequence of alpha S2-casein, when compared with the corresponding cavine A sequence, helps to define the boundaries of a large amino acid repeat (approximately 80 residues) whereas comparisons with the nucleotide sequences of rat gamma- and mouse epsilon-casein mRNAs also reveal extensive sequence similarities. An alignment of these four sequences shows that the divergence of their translated regions has been characterized by the duplication and deletion of discrete segments of sequence that probably correspond to exons. A high degree of nucleotide substitution is also found when the four sequences are compared, except for well-conserved leader-peptide and phosphorylation-site sequences and, to a lesser extent, the 5'-untranslated regions. Similar comparison of the bovine and rat beta-caseins shows that their divergence has involved a high rate of nucleotide substitution but that no major insertions or deletions of sequence have occurred. The several splice sites that have veen defined in the rat beta-casein gene are likely to have been conserved in the bovine. The contrasting evolutionary histories of the alpha- and beta-casein coding sequences correlate with the distinctive functions of these proteins in the casein micelle system in milk.      

Schistosoma mansoni:The Circulating Cathodic Antigen Forms an Abundant Product of 41/42 kDa in the Urine of Infected Patients

Abdeen, H. H., Attallah, A.-F. M., El-Mohamady, H. I., Harrison, R. A., and Mansour, M. M. 1998.Schistosoma mansoni: The circulating cathodic antigen forms an abundant product of 41/42 kDa in the urine of infected patients.Experimental Parasitology90, 286–289.     

Studies on mycoflora of salt marshes in Egypt. i. sugar fungi

Thirty-four genera and 92 species, in addition to two varieties of Aspergillus nidulans, were isolated from 74 soil samples collected from different localities of salt marshes in Egypt. Aspergillus (17 species in addition to 2 varieties of A. nidulans) and Penicillium (17 species) were of high occurrence, from which A. niger, A. fumigatus, A. terreus and P. notatum were dominant. Five genera were of moderate occurrence and these were Cladosporium, Fusarium, Alternaria, Mucor and Rhizopus. Nine genera were of low occurrence, namely, Drechslera, ?Trimmatostroma, Paecilomyces, Stachybotrys, Cephalosporium, Humicola, Botryotrichum, ? Geolegnia and Scopulariopsis. Statistical analyses reveal that soil samples poor in total fungi were significantly higher in total soluble salts, Na and K content than samples with numerous fungi. The difference in organic matter content between poor and rich samples was non-significant. In newly reclaimed fields along the borders of salt marshes, Fusarium was the most numerous fungal genera from soil followed by Aspergillus whereas Cladosporium was completely absent. Comparison between the present results and those of the other studies showed that there is no fungal flora characteristic of salt marshes.     

Selective effects of two systemic fungicides on soil fungi

BAS 317 00F was not toxic to the total count of fungi after 2 days but was regularly significantly toxic at the three doses after 5, 20 and 40 days and toxic at the low and the high doses after 80 days. In the agar medium, it was toxic to the counts of total fungi, Aspergillus, A. terreus, Rhizopus oryzae and Mucor racemosus at the high dose. Only the mycelial growth of Trichoderma viride which was significantly inhibited by the three doses when this fungicide was added to the liquid medium.Polyram-Combi induced two effects on the total population of soil fungi. One inhibitory and this was demonstrated almost regularly after 2, 10 and 40 days and the other stimulatory after 80 days of treatment with the low and the high doses. In the agar medium, this fungicide was very toxic to total fungi and to almost all fungal genera and species at the three doses. Several fungi could survive the high dose. In liquid medium, the test fungi showed variable degree of sensitivity and the most sensitive was Gliocladium roseum which was completely eradicated by the three doses.     

Effect of carbon levels from three organic substrates on egyptian soil fungi

Summary The fungal composition of soils with an equivalent percentage of carbon levels 2%, 5%, 10% and 20% fromOlea europea,, Citrus sinensis andEucalyptus rostrato leaves was studied after 10, 45 and 120 days using the dilution-plate method. They all induced significant increases in the total count of fungi, but their effect on the individual fungi was selective. The best substrate for the total fungus flora wasCitrus sinensis and the poorest wasOlea europeae leaves. The best three colonisers (possessing the highest counts), at carbon levels 2%, 5%, 10% and 20% at the end of the experimental periods were, respectively, as follows: forOlea europeae leaves,Scopulariaopsis brevicaulis, Drechslera halodes andCylindrocarpon sp.;Aspergillus quadrilineatus, A. sydowi andCurvularia lunata; A. quadrilineatus, Alternaria alternata andC. lunata andA. quadrilineatus, A. egyptiacus andA. terreus; forCitrus sinensis leaves,A. quadrilineatus, A. fumigatus andS. brumptii; A. fumigatus, A. quadrilineatus andA. versicolor; A. quadrilineatus, A. terreus andS. brumptii; andA. quadrilineatus, A. flavus andA. sydowi; and forEucalyptus rostrata leaves,A. quadrilineatus, Rhizopus stolonifer andA. sydowi; A. quadrilineatus, A. niger andA. terreus; A. niger, A. quadrilineatus andS. brevicaulis; andA. terreus, A. niger andA. quadrilineatus.     

Keratinolytic Fungi in Egyptian Soils

The frequency of occurrence of keratinolytic fungi in seventy soil samples, collected from different sites in Upper Egypt and in the coastal area of the Mediterranean, was determined by baiting with human and animal hairs and pigeon feathers. Twenty-one species, in addition to an unidentified species, which belong to sixteen genera were collected. Chrysosporium indicum, C. tropicum, C. keratinophilum, and Microsporum gypseum were the most frequent fungal species recovered from the baited soils. The soil samples collected from the salt marshes of the coastal Mediterranean area were completely free from any keratinolytic fungi, whereas the soil samples collected from cultivated soils contributed species, ranging from one to four species.