In vitro culture of arbuscular mycorrhizal fungi: advances and future prospects

Arbuscular mycorrhizal (AM) fungi are ecologically important for most vascular plants for their growth and survival. AM fungi are obligate symbionts. In recent years, there have been many attempts to cultivate in vitro. Some relevant results indicate efforts are not far from successful growth of AM fungi independent of a plant host. This paper describes the methods to cultivate root organs, and to select and purify AM fungal inocula (intraradical and extraradical forms). Axenic and monoxenic cultures of AM fungi are summarized and we propose a methodology to recover and achieve continuous culture of AM fungi without lost of infectivity. The in vitro systems have proved to be a valuable tool to study fundamental and practical aspects of AM symbiosis, complementing the in vivo experimental approaches. Finally, we give some proposals of in vitro AM researches to exploit more the potentialities of AM symbiosis. Key words: Arbuscular mycorrhizal fungi, continuous culture, root organ cultures, intraradical and extraradical forms, in vitro. African Journal of Biotechnology Vol. 2 (12), pp. 692-697, December 200

NEW TRANSITION METAL OXALATO COMPLEXES WITH DABCOH22+ AS ADVERSE CATION: SYNTHESIS AND INFRARED STUDY

On allowing DABCOH2(HC2O4)2 to react with transition metal dihalides in ethanol, a new series of complexes of general formula M(oxalate)2 DABCOH22+. nDABCOH22+.2X- (n=1/2;1) have been obtained. When (n=1) a dimeric structure is suggested, the two monomeric species being hold together by biprotonated DABCO through N-H…O hydrogen bonds. In the case of the complex M(oxalate)2DABCOH22+ .1/2 DABCOH22+.2X- -M = Ni, Cu- the structure is an infinite chain. The environment around the metallic centers is octahedral or square pyramidal. The oxalate behaves as a monochelating and hydrogen bonds involved ligand or is only concerned by hydrogen bonds

Characterization of strains of Aspergillus flavus and A. parasiticus isolated from groundnut (Arachis hypogea), rice (Oryza sativa) and maize (Zea mays) in Senegal

The contamination of certain food crop with aflatoxin poses a real public health problem for consumers and causes many market losses for exporters. Thus, several research works are oriented in the direction of developing methods to combat aflatoxinogenic fungus. This study aimed at identifying and characterizing strains of Aspergillus flavus and A. parasiticus on groundnut, maize and rice seeds grown or imported into Senegal. Four species (A. niger, A. tamarii, A. flavus and A. parasiticus) were isolated from the seeds with incidences ranging from 0 to 100% depending on the samples and their provenance. Six strains of A. flavus and 3 strains of A. parasiticus have been identified and characterized on CYA and G25N culture media. The characterization focused on the morphological characteristics (color and appearance, mycelial growth) of the colonies on the different culture media, and on some microscopic characteristics such as the density of sporulation (production of conidia) and the appearance of the conidiophore. Strains of A. flavus were more frequent on groundnuts and isolates with the same traits were also identified from rice and maize samples, hence the 3 strains of A. parasiticus were isolated

NEW TRANSITION METAL OXALATO COMPLEXES WITH DABCOH22+ AS ADVERSE CATION: SYNTHESIS AND INFRARED STUDY

On allowing DABCOH2(HC2O4)2 to react with transition metal dihalides in ethanol, a new series of complexes of general formula M(oxalate)2 DABCOH22+. nDABCOH22+.2X- (n=1/2;1) have been obtained. When (n=1) a dimeric structure is suggested, the two monomeric species being hold together by biprotonated DABCO through N-H…O hydrogen bonds. In the case of the complex M(oxalate)2DABCOH22+ .1/2 DABCOH22+.2X- -M = Ni, Cu- the structure is an infinite chain. The environment around the metallic centers is octahedral or square pyramidal. The oxalate behaves as a monochelating and hydrogen bonds involved ligand or is only concerned by hydrogen bonds

Solanum cultivar responses to arbuscular mycorrhizal fungi: growth and mineral status

A greenhouse experiment was carried out in a sandy soil with a low available phosphorus to evaluate responsiveness of four Solanum aethiopicum cultivars to indigenous arbuscular mycorrhizal fungi. Results showed clear interaction between genetic variability of cultivars and fungal isolates on shoot biomass and on mineral status. Arbuscular mycorrhizal fungi can be ranked as Glomus aggregatum > Glomus mosseae > Glomus versiforme for improving yield as well as nitrogen, phosphorus, and potassium acquisition of Solanum cultivars. Key words: Arbuscular mycorrhizal fungi, Solanum aethiopicum, sterile soil, relative mycorrhizal dependency. African Journal of Biotechnology Vol.2(11) 2003: 429-43

Study of the Effect of Pseudomonas Putida and Funneliformis Mosseae on the Growth and Productivity of Tomato (Solanum Lycopersicum L.) in Senegal

In Senegal, the Niayes zone plays an important role in the economy of the country. It is the main horticultural production area. Among the crops cultivated, tomato (Solanum lycopersicum L.) is the second place of horticultural crops. However, this crop is confronted with biotic and abiotic constraints leading to lower yields. Thus, the objective of this study is to evaluate the impact of beneficial microorganisms such as rhizobacteria from the group of fluorescent Pseudomonas (Pseudomonas putida) and arbuscular mycorrhizal fungi (Funeliformis mosseae) on the productivity of tomatoes. Soil samples were taken from the rhizosphere of tomato plants. The bacterial strains were isolated by the method of suspensions dilutions, and then seeded on King B medium. Their identification was carried out by using the MALDITOF mass spectrometer. In order to evaluate the effect of these microorganisms on productivity, an experiment was conducted in the field for three months. An experimental device with three randomize blocks was adopted with four block treatments: T (control), PS1 (Pseudomonas putida), Fm (Funneliformis mosseae) and PS1 + Fm. The results obtained showed that the inoculation of tomato plants with PS1 or in combination with Fm induced the best yields with values exceeding respectively 5 t / ha and 1.5 t / ha compared with non-inoculated plants. The yield reductions observed in the case of co-inoculation between Fm and PS1 compared with PS1 treatment alone would suggest an antagonistic effect. These strains of Pseudomonas putida constitute an alternative for the increase of tomato productivity in the Niayes zone