Investigation of the genetic structure and trait control of date palm (Phoenix dactylifera L.) germplasm from Oman and exploration of salt tolerance
Publication Date
July 30, 2026
Creator
Aljabri, Abdullah
Abstract
Date palm (Phoenix dactylifera L.) is a foundation crop for Oman and the wider Gulf region, yet its productivity and long-term sustainability are increasingly constrained by climate change, soil degradation, and rising salinity. This thesis integrates phenotypic, genomic, physiological, and transcriptomic approaches to characterise diversity, dissect the genetic architecture of yield-related traits, and clarify the mechanistic basis of salinity tolerance in Omani and Gulf date palm cultivars.
Phenotypic characterisation of 246 cultivars using vegetative, reproductive, and fruit descriptors revealed extensive morphological diversity, with fruit traits (e.g., fruit weight, pulp weight, pulp-to-seed ratio, and total soluble solids) emerging as the most stable and discriminative features, consistent with strong consumer-driven selection. In contrast, vegetative traits showed greater plasticity and clearer geographic structuring, particularly among Omani cultivars, supporting their utility for conservation planning and germplasm management.
Genome-wide association analyses using high-density SNP markers indicated a complex, polygenic basis for yield and fruit-quality traits. Prioritised loci linked to reproductive performance, fruit development, seed traits, and pigmentation converged on plausible pathways involving hormone signalling, transcriptional regulation, cell-cycle control, and transport processes, reinforcing the value of genomics for marker-assisted selection and genomic prediction in date palm improvement programmes.
Controlled salinity-stress experiments on ten Omani cultivars demonstrated that tolerance is multifactorial and best explained by coordinated ion homeostasis, osmotic adjustment, and antioxidant defence. Multivariate synthesis highlighted low Na⁺/K⁺ ratios, enhanced osmolyte accumulation, sustained antioxidant enzyme activity, and maintenance of photosynthetic function as robust, convergent indicators for screening and cultivar ranking under salinity.
Transcriptomic profiling of five contrasting cultivars under severe salinity stress revealed extensive transcriptional reprogramming comprising both conserved and genotype-specific responses. Core adaptive signatures included activation of stress signalling, antioxidant/redox regulation, ion transport, and protein homeostasis, alongside repression of growth- and photosynthesis-associated processes; differences in the magnitude and coordination of these responses help explain cultivar-specific tolerance strategies.
Collectively, the thesis supports an integrative improvement framework that links field-relevant phenotypes to genetic signals and molecular regulation, providing practical physiological and molecular markers to accelerate screening and breeding for salinity resilience and productivity in date palm.
Item Type
ethesis
Thesis Type
PhD
Supervisors
Associate Professor
Professor of Plant Pathology
Subjects (LC)
Associated Schools / Departments
UoN Repository URI
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