Sakina Elshibli

Microsatellite markers reveal high genetic diversity in date palm ( Phoenix dactylifera L.) germplasm from Sudan

Genetic diversity in date palm germplasm from Sudan representing 37 female and 23 male accessions was investigated using 16 loci of microsatellite (SSR) primers. Eight female accessions from Morocco were included as reference material. The tested SSR markers showed a high level of polymorphism. A total of 343 alleles were detected at the 16 loci. The number of alleles per marker ranged from 14 to 44 with an average of 21.4 per locus. A high level of expected heterozygosity was observed among Sudan cultivars (0.841), Morocco cultivars (0.820) and male accessions (0.799). The results indicate that the genetic groups of the Sudan cultivars and/or males do not follow a clear geographic pattern. However, the morocco group showed significant differentiation in relation to the Sudan groups, as measured by FST values and genetic distances. The effect of the methods of pollination and cultivar selection on the genetic structure was clearly detected by the weak clustering association that was observed for the majority of accessions originating from Sudan and Morocco as well. This suggests the need for further investigation on the genetic diversity of Sudanese date palm germplasm. A deeper insight will be revealed by a detailed analysis of populations originating from different geographic locations.

Biodiversity of date palms ( Phoenix dactylifera L.) in Sudan: chemical, morphological and DNA polymorphisms of selected cultivars

Date palm fruits of 15 cultivars were collected at harvest (Tamr stage) from the Nori Horticultural Orchard in the Northern State of Sudan for morphological and chemical characterization. Morphological and DNA polymorphisms of the mother trees were also investigated. Significant (P , 0.001) differentiation of cultivars in relation to tree height, and number and length of pinnae and spines was observed. Fruit weight, flesh weight and fruit and seed sizes expressed a wide range of diversity among cultivars. Significant differences were also observed among cultivars for all tested sugars (P , 0.001). Titratable acidity was found to be a characteristic feature of almost every cultivar. The results of DNA genotyping indicated high genetic diversity among cultivars with Nei’s genetic distances ranging from 0.693 to 3.496, and expected and observed heterozygosity equalling 0.837 and 0.950, respectively. This study highlights the diversity of date palms in Sudan, as represented by apparent morphological characters, chemical composition of fruits as well as DNA polymorphism. The employment of different techniques for data analyses gave conclusive ideas on some interrelationships among a large set of characters; the knowledge of such relationships can be utilized for screening date palm cultivars for possible descriptors.

Somaclonal Variation in Date Palm

The exploration of somaclonal variation is an approach that could provide date palm breeding programs with new genotypes. Naturally occurring or induced variants may have superior agronomic quality and/or enhanced performance but could also harbor new traits such as tolerance to drought and salinity or resistance to major diseases i.e. bayoud. This chapter summarizes recent progress in terms of studying and exploring date palm somaclonal variation, and provides an outlook about future applications of this biotechnology in this socioeconomically important crop.

Biodiversity in Date Palm: Molecular Markers as Indicators

Date palm, a tree known only as cultivated and under domestication for thousands of years with a wide range of distinct morphological diversity, has been a target of considerable research work, including, e.g. studies on both phenotypic and genetic diversity. Most research has focused on cultivar identification, where both types of markers – phenotypic and genetic – have been utilized. A wide range of molecular markers have been applied, yet, a relatively modest amount of results has been produced. In this chapter, existing knowledge of date palm biodiversity is reviewed. The usability and potential applications of molecular markers to detect biodiversity in plant species are discussed with special emphasis on date palm. Some powerful applications of molecular markers are not utilized or are underutilized, such as DNA sequencing approaches, which will provide a complete view of different events behind the evolution of the date palm genome, and positively enhance its utilization and conservation, especially under the circumstances of climate change and the scenarios expected to follow. Applications, such as germplasm conservation and management – apart from in situ conservation and seed bank strategies – will follow successful germplasm identification and development of efficient in vitro cloning and cryopreservation protocols. A detailed assessment of the date palm biodiversity and availability of information and research results are key factors for efficient utilization of date palm germplasm.

Genetic profiling of the critically endangered palm species Medemia argun using newly developed chloroplast DNA markers

ABSTRACT Background: Medemia argun is a rare wild palm tree species. Its global existence is assumed to include the main population of about 1000 trees in the Nubian Desert of Sudan and some scattered individuals in southern Egypt. The species had previously been assumed to be extinct, but then reported to be extant about 20 years ago. Aims: To assess genetic variation and explore population genetic structure of M. argun, through development and analysis of microsatellite markers. Methods: The genome sequence mining approach was applied in order to identify microsatellites in the chloroplast genome of Bismarckia nobilis, a species closely related of M. argun. A set of 49 markers were designed, and their characteristics are now provided. Seven chloroplast DNA markers were developed for use in the genetic characterisation of this threatened species. Results: Five markers were found polymorphic in M. argun, which enabled the assessment of the genetic diversity of the species. Significant genetic differentiation was observed among generations and collection sites, accompanied by low genetic variation. The seven markers developed were polymorphic among the wild relatives Hyphaene thebaica and Borassus aethiopum. Conclusions: This is the first study to report molecular markers for M. argun. Our results suggest that the genetic consequences of population fragmentation in M. argun are beginning to be evident.

Genetic variation of pedunculate oak (Quercus robur L.) in the urban woodlands of Helsinki

ABSTRACT We present a genetic profile of pedunculate oak (Quercus robur L.) in three woodlands of the Helsinki region. We genotyped all mature trees and samples of seedlings to evaluate patterns of genetic variation and gene flow, and evaluate the long-term stability and natural regeneration of these stands. Although five microsatellite loci showed no significant differences in heterozygosity between generations in most locations, significant (p < .05) pairwise differences were observed between mature trees and seedlings at Seurasaari, with higher diversity within seedlings. Ninety-four percent of the genetic variation occurred within sample sites. Background pollination contributed up to 61% of the diversity among seedlings, and thereby plays an important role in shaping the genetic variation and structure of future generations. Results indicate that pedunculate oak trees in the surveyed parks of Helsinki belong to the same population and that the urban environment per se does not interfere with gene flow over the distances represented here. Based on our findings, a minimal-maintenance program reliant upon natural regeneration of oak in the public parks of Helsinki seems plausible.