The Promising Potential of Triploidy in Date Palm (Phoenix dactylifera L.) Breeding.

Date palms are a vital part of oasis ecosystems and are an important source of income in arid and semi-arid areas. Crossbreeding is limited due to the long juvenile stage of date palms and their dioecious nature. The aim of this study was to create triploid date palms to obtain larger and seedless fruits and to increase resilience to abiotic stresses. A tetraploid date palm mutant was crossed with a diploid male palm, yielding hundreds of seeds suspected of containing triploid embryos. Six years after planting, four palms with confirmed triploidy reached maturity. They are phenotypically distinct from diploids, with a thicker rachis, thinner spines, wider and longer midleaf spines, and a longer apical spine. They were classified as sterile bisexual, sterile male and fertile female. One of the latter produced very tasty dates with a very small seed, which is promising for the marketability and profitability of date palm fruits. This first report on triploid date palms provides a way in which to make a significant leap forward in date palm breeding. Given the vigor and fruit quality of female triploid date palms, compared to their diploid counterparts, they will be the target of breeding programs and may spearhead new oases.

Whole mitochondrial and chloroplast genome sequencing of Tunisian date palm cultivars: diversity and evolutionary relationships.

BACKGROUND: Date palm (Phoenix dactylifera L.) is the most widespread crop in arid and semi-arid regions and has great traditional and socioeconomic importance, with its fruit well-known for its high nutritional and health value. However, the genetic variation of date palm cultivars is often neglected. The advent of high-throughput sequencing has made possible the resequencing of whole organelle (mitochondria and chloroplast) genomes to explore the genetic diversity and phylogenetic relationships of cultivated plants with unprecedented detail. RESULTS: Whole organelle genomes of 171 Tunisian accessions (135 females and 36 males) were sequenced. Targeted bioinformatics pipelines were used to identify date palm haplotypes and genome variants, aiming to provide variant annotation and investigate patterns of evolutionary relationship. Our results revealed the existence of unique haplotypes, identified by 45 chloroplastic and 156 mitochondrial SNPs. Estimation of the effect of these SNPs on genes functions was predicted in silico. CONCLUSIONS: The results of this study have important implications, in the light of ongoing environmental changes, for the conservation and sustainable use of the genetic resources of date palm cultivars in Tunisia, where monoculture threatens biodiversity leading to genetic erosion. These data will be useful for breeding and genetic improvement programs of the date palm through selective cross-breeding.

Phylogeographical Analyses of a Relict Fern of Palaeotropical Flora (Vandenboschia speciosa): Distribution and Diversity Model in Relation to the Geological and Climate Events of the Late Miocene and Early Pliocene.

Fern phylogeographic studies have mostly focused on the influence of the Pleistocene climate on fern distributions and the prevalence of long-distance dispersal. The effect of pre-Pleistocene events on the distributions of fern species is largely unexplored. Here, we elucidate a hypothetical scenario for the evolutionary history of Vandenboschia speciosa, hypothesised to be of Tertiary palaeotropical flora with a peculiar perennial gametophyte. We sequenced 40 populations across the species range in one plastid region and two variants of the nuclear gapCp gene and conducted time-calibrated phylogenetic, phylogeographical, and species distribution modelling analyses. Vandenboschia speciosa is an allopolyploid and had a Tertiary origin. Late Miocene aridification possibly caused the long persistence in independent refugia on the Eurosiberian Atlantic and Mediterranean coasts, with the independent evolution of gene pools resulting in two evolutionary units. The Cantabrian Cornice, a major refugium, could also be a secondary contact zone during Quaternary glacial cycles. Central European populations resulted from multiple post-glacial, long-distance dispersals. Vandenboschia speciosa reached Macaronesia during the Pliocene-Pleistocene, with a phylogeographical link between the Canary Islands, Madeira, and southern Iberia, and between the Azores and northwestern Europe. Our results support the idea that the geological and climate events of the Late Miocene/Early Pliocene shifted Tertiary fern distribution patterns in Europe.

Gamma irradiated date syrup for sucrose substitution in yogurt: effect on physicochemical properties, antioxidant capacity and sensory evaluation.

In the search for domestic natural additives favored by consumers for food flavor and antioxidant enhancement, this work aimed to estimate the influence of the substitution of sucrose by date syrup treated with gamma rays on the physico-chemical properties, antioxidant capacity and organoleptic quality of yogurt. Date syrup was irradiated by two different doses: 1 kGy and 2 kGy and incorporated into yogurt with different sucrose substitution percentages. The obtained results showed that gamma irradiation improved the microbiological quality of the date syrup while retaining its physicochemical quality. In fact, a significant reduction of the microbial charge was observed. The two-irradiation doses were proven not affected the total sugars, proteins, phenols or the syrup antioxidant activity. Besides, water content and color indices were found to decrease. The substitution of sucrose at the rate of 75 and 100% with date syrup irradiated by the dose of 1 kGy enhances the antioxidant activity, phenol, protein and sugar content of the prepared yogurt. Furthermore, yogurt with irradiated date syrup gave good sensory scores. The treated syrup, especially by the dose of 1 kGy, could be a promising technological path. This gamma irradiation guarantees a biological method for preserving the syrup for its use in the engineering of processes applied to the dairy industry. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s13197-021-05000-z.