Diversity, phylogeny and distribution of bean rhizobia in salt-affected soils of North-West Morocco

Different molecular methods: BOX-PCR fingerprinting, R-FLP-PCR and sequencing of the 16S rDNA as well as the symbiotic genes nodC and nifH, were used to study the genetic diversity within a collection of nodulating bean rhizobia isolated from five soils of North-West Morocco. BOX fingerprints analysis of 241 isolates revealed 19 different BOX profiles. According to the PFLP-PCR and sequencing of 16S rDNA carried out on 45 representative isolates, 5 genotypes were obtained corresponding to the species Rhizobium etli, R. tropici, R. gallicum, R. leguminosarum and Sinorhizobium meliloti. The most abundant species were R. etli and R. tropici (61% and 24%, respectively). A high intraspecific diversity was observed among the R. etli isolates, while the R. tropici group was homogeneous. Most of the rhizobia studied belong to species known to nodulate common bean, while 2 species were unconventional microsymbionts: R. leguminosarum biovar viciae and S. meliloti. Our results, especially the nodulation promiscuity of common bean and the relation between the predominance of some species of rhizobia in particular soils and the salt content of these soils, indicate that there is a real need for a better understanding of the distribution of common bean rhizobia species in the soils of Morocco before any inoculation attempt.

The Epipalaeolithic (Iberomaurusian) at Grotte des Pigeons (Taforalt), Morocco: a preliminary study of the land Mollusca

Land snail middens occur widely throughout the circum-Mediterranean, particularly in the Maghreb and Libya, but are relatively understudied when compared with the better known coastal marine middens. The site of Taforalt (Grotte des Pigeons) in north east Morocco contains thick ashy deposits with considerable numbers of land snails, dating between 13,000 and 11,000 BP. The site has been excavated periodically since its discovery in 1908, but little attention has been paid to the land snail component. Recent excavations at the site as part of the Cemeteries and Sedentism Project has facilitated reinvestigation of the Iberomaurusian layers, including the upper ashy midden unit. This investigation addresses questions surrounding chronological variation in the lithic assemblage, subsistence strategies, population health and mortuary practices. Preliminary work on the land snails has identified a low species diversity in the grey series midden layers, characterised by the large edible species Alabastrina alabastrites, Helix cf aspersa, Dupotetia dupotetiana, Otala punctata and Cernuella sp, which appear to represent an abrupt intensification in the use of land snails as a food source. Significant quantities of associated plant material and animal bone suggest that land snails are part of a broader based diet which is adopted from around 13,000 BP.