Morphological variability of Mauritanian date-palm (Phoenix dactylifera L.) cultivars as revealed by vegetative traits

The aim of this study was to use morphological markers to characterize twelve Mauritanian date-palm ecotypes currently grown by farmers. Eighteen phenotypic traits describing the vegetative systems were measured in the field in Atar Oasis. The data set was analyzed by principal components analysis (PCA) and UPGMA clustering. PCA revealed a great variability among the cultivars. Fourteen out of the 18 characters studied showed a high discriminating power suggesting their possible uses in the establishment of a Mauritanian date-palm catalogue. UPGMA Clustering revealed association between cultivars with similar fruit characteristics indicating that these ecotypes are morphologically related. Results also showed that individuals belonging to the Ahmar cultivar were morphologically distinct, suggesting it is likely a polyclonal variety

L'intégration de l'ethnobotanique et de la génétique des populations met en évidence l'agrobiodiversité des palmiers dattiers de l'oasis de Siwa (Égypte) et leur importance pour l'histoire évolutive de l'espèce.

Crop diversity is shaped by biological and social processes interacting at different spatiotemporal scales. Here we combined population genetics and ethnobotany to investigate date palm (Phoenix dactylifera L.) diversity in Siwa Oasis, Egypt. Based on interviews with farmers and observation of practices in the field, we collected 149 date palms from Siwa Oasis and 27 uncultivated date palms from abandoned oases in the surrounding desert. Using genotyping data from 18 nuclear and plastid microsatellite loci, we confirmed that some named types each constitute a clonal line, i.e. a true-to-type cultivar. We also found that others are collections of clonal lines, i.e. ethnovarieties, or even unrelated samples, i.e. local categories. This alters current assessments of agrobiodiversity, which are visibly underestimated, and uncovers the impact of low-intensity, but highly effective, farming practices on biodiversity. These hardly observable practices, hypothesized by ethnographic survey and confirmed by genetic analysis, are enabled by the way Isiwans conceive and classify living beings in their oasis, which do not quite match the way biologists do: a classic disparity of etic vs. emic categorizations. In addition, we established that Siwa date palms represent a unique and highly diverse genetic cluster, rather than a subset of North African and Middle Eastern palm diversity. As previously shown, North African date palms display evidence of introgression by the wild relative Phoenix theophrasti, and we found that the uncultivated date palms from the abandoned oases share even more alleles with this species than cultivated palms in this region. The study of Siwa date palms could hence be a key to the understanding of date palm diversification in North Africa. Integration of ethnography and population genetics promoted the understanding of the interplay between diversity management in the oasis (short-time scale), and the origins and dynamic of diversity through domestication and diversification (long-time scale)

Génotypage d’une collection tunisienne de palmier dattier par les marqueurs microsatellites

Introduction Les oasis tunisiennes sont caractérisées par une richesse génétique considérable comme en témoigne la présence d’au moins 250 cultivars répertoriés (Rhouma, 1994). Cependant, avec l’évolution économique et sociale du pays, les palmeraies de Djérid et de Nefzaoua sont réorganisées pour satisfaire une demande sans cesse croissante en dattes de qualité supérieure à l’instar du cultivar « élite » Deglet Nour. Cette réorganisation a fait que la phoéniciculture est passée d’un système ..

Molecular polymorphism and genetic relationships in date palm (Phoenix dactylifera L.): The utility of nuclear microsatellite markers

Due to the economic importance of the date palm in Tunisia, we attempt to develop microsatellite markers for the genetic characterisation and identification of cultivars. This characterisation will enable us to obtain an extensive understanding of the local genetic diversity and its distribution. Fourteen microsatellite loci of Phoenix dactylifera L. were tested to examine the genetic diversity in the Tunisian date palm germplasm: 74 female and 27 male cultivars were represented. A total of 136 alleles and 311 genotypes were detected based on 14 loci microsatellite. A high level of polymorphism was detected at the DNA level. The 101 date palms from three main oases exhibited a high degree of generic diversity and were structured independently of their geographical origin and sex. All the local date palm accessions were successfully fingerprinted and easily distinguished based on only five loci. The possibility of using microsatellites in the large-scale molecular labelling of offshoots and in vitro plantlets and in the certification of plant material is discussed

Contribution à l’étude transcriptomique de la maladie des feuilles cassantes chez le palmier dattier en Tunisie (Phoenix dactylifera L.)

Introduction Le palmier dattier (Phœnix dactylifera L.) est considéré comme étant l’arbre de vie dans les régions sahariennes des pays de l’Afrique du Nord et du Moyen-Orient. En effet, cette plante dioïque et pérenne, constitue l’axe principal de l’agro-système oasien. A ce sujet, le palmier dattier joue un important rôle socioéconomique en Tunisie. En outre, il constitue la base de la production agricole ainsi que la principale source financière et alimentaire des oasiens. Cependant, en dép..

Exploration of bacterial diversity in leaves and rhizosphere soil of flood affected and unaffected apricot trees

International audiencePlants harbor diverse and taxonomically structured communities of protective microorganisms that confer beneficial characteristics in plant growth and protection against biotic and abiotic stresses. The aim of this study is to characterize the composition of endophytic bacterial communities in leaves and rhizobacterial communities of the flood affected and unaffected apricot trees by 16S rRNA genes metabarcoding. Results showed a slight bacterial diversity reduction in flood affected condition compared to the unaffected one. The relative bacterial abundance analysis showed that the bacterial taxa were almost uniformly distributed between the leaves. However, a clear differential taxa abundance was observed in rhizosphere soil which may be associated with apricot tree environmental status. In fact, the flood affected rhizosphere soil showed a significant increase in several bacterial taxa including particularly Bacillusfrigoritolerans and Pseudoarthrobacterphenanthrenivorans which are known to be beneficial to soil. However, some Actinobacteria genera that promote growth of plants, including Nocardioidessp.,Streptomycessp.,BlastococcusandGeodermatophilus were decreased in abundance. This distribution of abundance and diversity of the bacterial community in the flood affected tree can be correlated to abiotic stress. These results provide new insights into rhizosphere-associated microbes that are likely playing a crucial role in plant growth and survival

Genetic diversity of Southeastern Nigerien date palms reveals a secondary structure within Western populations

International audienceDate palm (Phoenix dactylifera L.) is mainly cultivated for its edible fruit and is of great socio-economic importance for the populations of arid zones. Analysis of the date palm genetic diversity in the Old World had revealed a strong genetic structure with the existence of two gene pools, one Eastern comprising Asia and Djibouti, and one Western, consisting of North African accessions. So far, mainly date palm populations from countries within the Maghreb and the Middle East were characterized, but no information from the Sahel was included. Here, we present the genetic diversity of date palms from Southeastern Niger. The DNA of 113 date palm accessions were analyzed and compared with a database containing the genetic information of 248 accessions from the Old World. The diversity generated from microsatellite markers was compared to that of the same loci of both the Eastern and Western genetic pools. Our results show that date palms from Southeastern Niger constitute a unique group with a high level of genetic diversity. Moreover, even though this group is included in the Western genetic pool, it shows a specific originality which differentiates it from other Western populations. It also shows one of the lowest admixture levels of the Western pool. Global analysis showed a secondary genetic structure within the Western pool highlighting a new genetic group located in Southeastern Niger that distinguishes itself from the North African group