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

Tamarind (Tamarindus indica L.) parkland mycorrhizal potential within three agro-ecological zones of Senegal

Introduction. Tamarind (Tamarindus indica L.) belongs to the Fabaceae family; it is a multipurpose tree with slow growth. In order to help improve its growth and development, we assessed mycorrhizal diversity of tamarind parklands in Senegal. Materials and methods. Three sites of tamarind populations were sampled for each agro-ecological zone in Senegal: the Sahelian zone (i), Sahelo-Sudan zone (ii) and Sudan zone (iii). Soil and root samples were collected in each site and used for arbuscular mycorrhizal (AM) spore isolation and root colonization assessment. We identified the mycorrhizal fungi from spore collections and evaluated the root mycorrhization rate, defined as percentage of roots colonized according to agro-ecological zones. Results and discussion. The results did not reveal a specific AM fungal strain associated with tamarind plants. Three arbuscular mycorrhizal fungi (AMF) were identified from spores on the genus level: Glomus, Scutellospora and Acaulospora. Tamarind sites with sandy soil texture (70-90%) and located in dry areas (Sahel and Sudano-Sahel zones) were shown to be rich in mycorrhizal propagules. High densities of soil AM propagules evaluated with the Most Probable Number method (MPN) were found in Niokhoul (1100 propagules per 50 g of soil), Sakal (790 propagules per 50 g of soil) and Mbassis (780 propagules per 50 g of soil). However, higher mycorrhizal colonization (11%) was observed in the Sahel agro-ecological zone compared with the Sudano-Sahelian and Sahelian zones (3%) of Senegal. Conclusion. Our study explored natural AMF diversity as a starting point to develop inocula to be used in commercial nursery production of tamarinds

Power Modeling for Heterogeneous Processors

As power becomes an ever more important design consideration, there is a need for accurate power models at all stages of the design process. While power models are available for CPUs and GPUs, only simple models are available for heterogeneous processors. We present a micro-benchmarkbased modeling technique that can be used for chip multiprocessor (CMPs) and accelerated processing units (APUs). We use our approach to model power on an Intel Xeon CPU and an AMD Fusion heterogeneous processor. The resulting error rate for the Xeon’s model is below 3 % and is only 7% for the Fusion. We also present a method to reduce the number of benchmarks required to create these models. Instead of running micro-benchmarks for every combination of factors (e.g. different operations or memory access patterns), we cluster similar micro-benchmarks to avoid unnecessary simulations. We show that it is possible to eliminate as many as 93 % of the compute micro-benchmarks, while still producing power models having less than 10 % error rate

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

Influence in vitro de divers facteurs abiotiques (température, pH, salinité) sur la croissance mycélienne de trois souches locales de Trichoderma sp.

Les Trichoderma sont des champignons imparfaits saprophytes que l’on retrouve dans divers milieux comme le sol, le bois mort, les débris des végétaux et les organes aériens des plantes. Ils ont un rôle phytoprotecteur et stimulateur du développement des plantes associées. L’effet de différents facteurs abiotiques (température, pH, salinité) sur la croissance mycélienne de trois souches locales de Trichoderma a été évalué. Ces souches ont été isolées à partir de la rhizosphère de la tomate. Une étude préliminaire a été effectuée sur quatre milieux de culture (PDA, MEA, SB et DOX) pour la sélection du milieu d’étude. Les résultats obtenus montrent que le milieu PDA permet une meilleure croissance des souches de Trichoderma. La température optimale de croissance des différentes souches est de 29 °C et le pH 5 se révèle être le plus adéquat pour la culture des Trichoderma. Cette étude montre également que les souches de Trichoderma résistent à des concentrations de sel (NaCl) allant jusqu’à 3%.© 2016 International Formulae Group. All rights reserved.Mots clés: Trichoderma, facteurs limitant, température, pH, salinité, milieu de cultureEnglish Title:  In vitro influence of various abiotic factors (température, pH, salinity) on mycelium growth of three local strains of Trichoderma sp.English AbstractTrichoderma are saprophytic imperfect fungi that are found in various environments such as soil, dead wood, vegetable fragments and plant aerial organs. They protect and stimulate development of related plants. Effects of various abiotic factors (temperature, pH, salinity) on mycelium growth of three local Trichoderma strains were investigated. These strains were isolated from tomato rhizosphere. A preliminary study was performed on four culture media (PDA, MEA, SB and DOX) for the selection of the best media. The results  showed that PDA medium was highly growth of Trichoderma strains. The optimum temperature for growth of different strains is 29 °C and pH 5 was found to be most suitable for Trichoderma culture. Indeed, Trichoderma strains resistant to salt concentrations (NaCl) up to 3%.© 2016 International Formulae Group. All rights reserved.Keywords: Trichoderma, limiting factors, temperature, pH, salinity, culture medi

Germination Stage Screening of Mutants of Cowpea (Vigna unguiculata L. Walp) to Salinity Tolerance

To test the tolerance of cowpea mutants to salinity, cowpea wilds and mutants were subjected to 50, 100, 150, 200, and 250 mM NaCl to test for tolerance to salinity. Genotype and salt concentration interaction were significant. GxS explained mostly the variation observed. More informative salt concentrations were found in 50 mM (99.08) and C100 mM (72.50) against 26.80 in the control environment. High salt concentrations had the lowest germination rates. Seed germination rate of cowpea genotypes decreased from 56.46 to 20.58 with a mean of 36.28 and a variance of 99.08. Despite strong correlations observed between indices, very weak ones were found between AD and STI, -0.02, -0.44, -0.7, -0.79 and -0.84 respectively at salt concentration of 50, 100, 150, 200 and 250. Mouride wild types were most tolerant to salt with a germination rate of 43 % at 50 mM versus 48 and 551 % for respectively Melakh and Yacine. Six (6) mutants were more tolerant to the weakest checks performance which was the 9th best performance

Effet de la salinité sur la germination graines et la croissance des semis de treize cultivars africains de sésame (Sesamum indicum L.)

Le sésame (Sesamum indicum L.), une plante annuelle autoféconde originaire d’Afrique et d’Inde, est très sensible aux stades de germination et de semis mais modérément tolérant aux stress hydrique et salin. Cette étude menée en serre a pour objectif d’évaluer l’effet de différentes concentrations de NaCl sur la germination des graines et la croissance des semis de treize cultivars africains de sésame provenant du Sénégal, du Burkina Faso, du Cameroun et du Soudan. Un dispositif à blocs randomisés avec deux facteurs et trois répétitions a été utilisé . Les résultats montrent un effet négatif du gradient de salinité sur les taux de germination, de survie, la biomasse fraiche, la biomasse sèche, le diamètre au collet et la longueur de la tige. Les cultivars AS09, AS13, AS14, AS15, AS19 et AS25 ont été moins affectés par la salinité. L’importance de l’effet dépressif dépend de la concentration de sel et de la variété de cultivar de sésame. Sesame (Sesamum indicum L.), an annual self-pollinating plant native to Africa and India, is very sensitive to the stages of germination and sowing but moderately tolerant to water and salt stress. The objective of this greenhouse study is to assess the effect of different NaCl concentrations on seed germination and seedling growth of thirteen African sesame cultivars from Senegal, Burkina Faso, Cameroon and Sudan. A randomized block device with two factors and three replicates was used. The results show a negative effect of the salinity gradient on the germination rate, survival, fresh biomass, dry biomass, diameter at the collar and length of the stem. Cultivars AS09, AS13, AS14, AS15, AS19 and AS25 were less affected by salinity. The magnitude of the depressive effect depends on the concentration of salt and the sesame cultivar. &nbsp