Synthesis of Furanylalkyl Hex- and Pentenopyranosid-4-uloses

A few novel furanylalkyl hex- and pentenopyranones have been synthesized from the corresponding  hexenopyranosides or hydroxymethylfurfural. In the hexose series, the reactions proceeded through monosilylation of the primary alcohol followed by oxidation of secondary alcohols. The pentenopyranones have been obtained by glycosidation of hydroxymethylfurfural oxidation product.KEYWORDS: Hydroxymethylfurfural (HMF), silylation, oxidation, pyranone

Long term effect of municipal solid waste amendment on soil heavy metal content of sites used for periurban agriculture in Ngaoundere, Cameroon

An assessment of the impact of amendment using untreated municipal solid wastes on the trace element contents of periurban areas soils was carried out in  Ngaoundere. Waste samples were collected in November and soil samples were collected in November, January, April and July. Heavy metal total concentrations in urban wastes differed significantly among sites and ranged from 0.48 to 7.64 mg/kg for Cd, 38.3 to 236 mg/kg for Cu, 44.06 to 58.03 mg/kg for Ni, 117 to 528 mg/kg for Pb and 270 to 2110 mg/kg for Zn. These levels were out of the critical level for agricultural use at Camp prison (for Pb and Zn), Norvegien (for Cd, Cu and Zn), and Sabongari Gare site (for Cd, Cu and Zn). The levels of Ni in urban wastes from all sites and the levels of all heavy metals in urban wastes from Douze Poteaux site were lower than the critical level. The results revealed that the soil total  concentrations of Cu, Zn, Cd and Pb were below the typical agricultural soil critical level for the soil control and out of the critical level for amended soils. The levels of Ni were found to be within the normal range at all sites. The highest available  concentration of Zn (139.17 mg/kg) was found in November, Fe (843.23 mg/kg) and Pb (38.82 mg/kg) in January and Cu (19.09 mg/kg) and Ni (8.98 mg/kg) in July.  The available concentrations of Cd did not differ among periods. The highest   bioavailable factor (BF) of Zn, Ni and Pb was found at Douze Poteaux site and of Cd and Cu at Sabongari Gare site.Key words: Heavy metals, soils, municipal solid wastes, amendment, bioavailability factor

Isolation and identification of bioactive compounds from kernel seed cake of the mango (Mangifera indica Lam)

The ethanol extract and ethyl acetate fraction of Mangifera indica kernel seed cake inhibited the growth of Staphylococcus aureus and Pseudomonas aeruginosa. The bioactive compounds were isolated and identified by NMR, UV and mass spectrometry as methyl gallate, gallic acid and penta-O-galloylglucose. Theisolated methyl gallate and penta-O-galloylglucose also showed significant antibacterial activities against Staphylococcus aureus and Pseudomonas aeruginosa.Keywords: Mangifera indica, kernel seed cake, antibacterial activity, gallic acid, penta-O-galloylglucose, methyl gallate

Long-term effect of Mali phosphate rock on the grain yield of interspecifics and saltiva rice cultivars on acid soil in a humid forest zone of Côte d’Ivoire

To generate knowledge of upland rice intensification in West Africa, the grain yields of four interspecific cultivars (V2 = WAB450-1 B-P-38-HB; V3 = WAB450-11-1-P-40-HB; V4 = WAB450-11-1-P-40-1-H; and V5 = WAB450-24-3-2-P-18-HB) were compared with that of a soil acidity tolerant sativa (WAB 56-104 = V1) on acid soil at Man in the humid forest zone in Côte d’Ivoire during five cropping seasons (1998, 1999, 2000, 2001 and 2002). Nitrogen and potassium were annually applied at 100 and 50 kg ha-1 respectively. Mali phosphate rock from Tilemsi was applied once in 1998 at 0, 150, 300 and 450 kg P ha-1 in a randomized complete block design with three replications. The results revealed a grain yield ranging from 0.5 t ha-1 to 2.6 t ha-1 with highest productivity of interspecific cultivars V3 and V4 even at 0 kg P ha-1 compared to acid tolerant saltiva (V1). Annual optimum rates of P application were determined at 31.5 and 45 kg P ha-1 respectively for V3 and V4. Applying Mali PR at 31.5 and 45 kg P ha-1 respectively for V3 and V4 was recommended for upland rice intensification in the humid forest zone of Côte d’Ivoire.Keywords: Mali phosphate rock, rice, Côte d’Ivoire, interspecific, acid soil

Activite Pathologique Comparee de Deux Isolats de Colletotrichum gloeosporioïdes (PENZ.) sur Deux Varietes de Mangues (Mangifera indica L.)

L’anthracnose, causée par des champignons, est la 2e contrainte majeure à la production et l’exportation de mangues en Côte d’Ivoire. La présente étude vise à déterminer la pathogénicité de deux isolats Bo et Ko de Colletotrichum gloeosporioïdes (Penz.), agent causal de l’anthracnose. Les isolats ont été obtenus à partir d’explants des variétés Brooks (Bo) et Kent (Ko), mis en culture sur milieu PDA. Des fruits issus des variétés Brooks et Kéit ont été inoculés avec des disques mycéliens à travers une « inoculation douce » et une « inoculation brutale ». Les fruits inoculés ont été suivis pendant 14 j, date d’apparition des lésions causées par le champignon, ainsi que l’évolution leur taille ont été notées. Les résultats ont révélé que les deux isolats utilisés n’ont induit aucune lésion sur les deux variétés par la méthode « d’inoculation douce » au 9e j. Par contre, lorsque l’inoculation a été précédée d’une blessure, des lésions ont été observées chez les variétés Brooks et Kéit au 7e j après inoculation. Les tailles des lésions induites chez la variété Kéit par les isolats Ko (1,09 ± 0,08 cm) et Bo (0,19 ± 0,11 cm) ont été significativement différentes au 7e j. Les taux de lésions induites ont été statistiquement identiques avec les isolats Ko (100 %) et Bo (80 à 85 %), dès le 9e j. Par ailleurs, l’isolat Ko s’est révélé le plus virulent. Enfin, le travail a montré que Colletotrichum gloeosporioïdes (Penz.) est un pathogène capable de détériorer la qualité des mangues après récolte, avec une action plus marquée lorsque des blessures surviennent avant ou durant l’infection par les pathogènes.Mots clés : Mangue, Colletotrichum gloeosporioïdes, anthracnose, inoculation, Côte d’Ivoire.The anthracnose, caused by fungi is the second major obstacle in mangoes production and exportation in Côte d’Ivoire. This study has been done to evaluate the pathogenicity of two isolates Bo and Ko of Colletotrichum gloeosporioïdes (Penz.), an agent responsible for anthracnose in mango fruits. Fungi isolates were obtained from Brooks (Bo) and Kent (Ko) mango varieties and cultivated in pure PDA medium. Some fruits from Brooks and Kéit varieties were inoculated with fungi mycelium discs on both previously wounded and unwounded fruits. The inoculated fruits were monitored for 14 days and dates of lesion occurrence and expansion on fruit were recorded with time. Results revealed that both isolates did not cause any lesion on both varieties with the unwounded technique on the 9th day. However, when inoculation was preceded by a wound on the fruit, some lesions were observed with Brooks and Kéit varieties, on the 7th day after inoculation. The length of lesion induced on Kéit variety by Ko isolates (1.09 ± 0.08 cm) and Bo (0.19 ± 0.11 cm) differed significantly on the 7th day. No significant differences in lesion rate induced with the Ko isolates (100 %) and Bo (80 to 85 %) from the 9th day. Besides, Ko shows itself the most virulent. This work revealed that Colletotrichum gloeosporioïdes (Penz.) was a pathogen capable of deteriorating mango fruit quality after harvest, with a more serious impact when the wound occurred before fungi infection.Key words : Mango, Colletotrichum gloeosporioïde, anthracnose, inoculation, Côte d’Ivoire

Nutrient constraint of rainfed rice production in foot slope soil of Guinea Forest in Côte d’Ivoire

Soil nutrient deficiencies can affect rice yield and grain mineral content wherever they occur, but an understanding of their effect on upland rice production in humid forest zone of West Africa is still limited. Therefore, a nutrient omission trial was conducted on foot slope soil in 2003, 2004 and 2005 in Côte d’Ivoire using rice variety WAB 56–104. The effect on rice grain yield (GY) and nutrient content of complete fertilizer (Fc with nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg) and zinc (Zn)) was compared with Fc from which a specific nutrient was excluded (Fc – N, Fc – P, Fc – K, Fc – Ca, Fc – Mg and Fc – Zn). Before the trial, soil K (0.10 cmol kg−1) and Mg (0.20 cmol kg−1) contents were suitable, but available P-Bray I (4.2 mg kg−1) was found to be deficient. In course of the study, K, Mg and P deficiencies were observed. An antagonistic effect was observed between rice GY and grain concentrations in P, Mg and Ca for treatments Fc – Mg, Fc – P and Fc – K, respectively. Therefore, the use of P, K and Mg fertilizers is recommended for successive cropping seasons in order to rich stable and high rice yield while decreasing of grain concentrations in P, Mg and Ca can be observed

Existence of Several Pathotypes among Rice Yellow Mottle Virus (RYMV) Isolates Collected in Niger Republic

This study has been conducted in screen house with an aim to asses the Rice yellow mottle virus pathogenic diversity and the level of resistance of released varieties in Niger republic. Sixty RYMV isolates from 23 Niger rice perimeters were inoculated mechanically to nine rice cultivars. The disease symptoms were scored at 42 days after inoculation. Analysis of Variance (ANOVA) and Additive Main effect and Multiplicative Interaction (AMMI) analysis were performed on the percentage of severity. The reaction of the rice cultivars to the virus isolates was significantly different. The interaction between isolates and rice cultivars was also significant. AMMI cluster analysis revealed the existence of four major pathotypes (Path 1 to 4) of Rice Yellow Mottle Virus (RYMV) in Niger republic. Path 4 pathotype included 12 resistance breaking isolates (20%). Path 3 and Path 2 pathotypes consist of 15 and 26 isolates respectively and were typical of wild type isolates with moderate level of pathogeny, including none aggressive (path 3 = MP) and aggressive isolates (Path 2 = MPA). The fourth pathotype Path 1 was made of 7 isolates and typical of particular isolates which have a moderate pathogenic level (FP). Resistance Breaking (RB) isolates occupied 30% of Niger rice ecologies in variable proportion. The rice varieties (Bassiroumo, IR15-29-690-3-1 and Kassoumo) released in Niger were highly susceptible to RYMV and therefore constituted a favorable condition for the rice yellow mottle disease propagation. This information is useful in rice breeding programs in the development and deployment of RYMV resistant cultivars to different rice perimeters in Niger Republic

A reassessment of the epidemiology of Rice yellow mottle virus following recent advances in field and molecular studies

The available knowledge on the epidemiology of Rice yellow mottle virus (RYMV) is reassessed in the light of major advances in field and molecular studies of the disease it causes in rice. Previously undescribed means of transmission by mammals and through leaf contact have been discovered recently. Several agricultural practices, including the use of seedbed nurseries, have also contributed to a massive build-up of RYMV inoculum. Phytosanitation is now known to be critical to reduce disease incidence in rice. A new model of the ecology of RYMV in which man plays a central role has emerged. Furthermore, estimates of the evolutionary rate of change of RYMV provided a time-frame for its epidemiology, the first attempt for a plant virus. Earlier interpretations of the patterns of virus diversity which assumed a long-term evolution, and assigned a major role to adaptive events had to be discarded. In contrast, a wave-like model of dispersal of RYMV, which postulates its initial diversification in East Africa, followed by westward spread across the continent, was developed, refined and dated. The most salient - and largely unexpected - finding is that RYMV emerged recently and subsequently spread rapidly throughout Africa in the last two centuries, Diversification and Spread of RYMV has been concomitant with an extension of rice cultivation in Africa since the 19th century. This major agro-ecological change increased the encounters between primary hosts of RYMV and Cultivated rice. It also modified the landscape ecology in ways that facilitated virus spread

Rice Yellow Mottle Virus, an RNA Plant Virus, Evolves as Rapidly as Most RNA Animal Viruses▿ †

The rate of evolution of an RNA plant virus has never been estimated using temporally spaced sequence data, by contrast to the information available on an increasing range of animal viruses. Accordingly, the evolution rate of Rice yellow mottle virus (RYMV) was calculated from sequences of the coat protein gene of isolates collected from rice over a 40-year period in different parts of Africa. The evolution rate of RYMV was estimated by pairwise distance linear regression on five phylogeographically defined groups comprising a total of 135 isolates. It was further assessed from 253 isolates collected all over Africa by Bayesian coalescent methods under strict and relaxed molecular clock models and under constant size and skyline population genetic models. Consistent estimates of the evolution rate between 4 × 10−4 and 8 × 10−4 nucleotides (nt)/site/year were obtained whatever method and model were applied. The synonymous evolution rate was between 8 × 10−4 and 11 × 10−4 nt/site/year. The overall and synonymous evolution rates of RYMV were within the range of the rates of 50 RNA animal viruses, below the average but above the distribution median. Experimentally, in host change studies, substitutions accumulated at an even higher rate. The results show that an RNA plant virus such as RYMV evolves as rapidly as most RNA animal viruses. Knowledge of the molecular clock of plant viruses provides methods for testing a wide range of biological hypotheses