Male diversity matters: Genetic structuring of insular male date palm (Phoenix dactylifera L.) revealed valuable breeding and conservation resources

Most male date palms available for pollinating different female cultivars have mainly originated from seed propagation resulting in many different local males that represent a source of genetic diversity. Favorable fruit production is related to quality of pollen and its compatibility with a certain female variety. Therefore, the genetic characterization of the male pollen as a superior one for each female cultivar should be the first step to establish an intensive program to produce superior males through different procedures. In this study, the genetic diversity and population structure of 72 male date palm accessions were investigated using 15 microsatellite loci. A total number of 125 alleles was detected with an average of 8.33 alleles per locus. Bayesian model-based clustering analysis indicated the presence of two differentiated endemic male date palm genetic clusters, continental and insular, with the presence of introduced accessions originating from the Middle East. The diversity analysis in the insular region of Tunisia, which had never been performed before, revealed that this germplasm enclosed valuable endemic resources supporting the hypothesis of the presence of wild material.
These findings are crucial for identifying interesting genotypes that can be integrated into international coordinated actions of Phoenix dactylifera L. breeding programs as well as for the protection and conservation of valuable resources.

当前用于为不同雌性海枣栽培品种授粉的雄性种质材料，多数源自实生繁殖，由此衍生出诸多各具特色的本土雄性株系，构成了遗传多样性的重要来源。优质果品的产量与花粉质量，以及花粉与特定雌性品种的授粉亲和性密切相关。因此，针对每个雌性栽培品种，对其适配的优良雄性花粉开展遗传特征分析，应成为通过多种技术流程构建集约化优良雄性株系培育项目的首要步骤。本研究利用15个微卫星位点（microsatellite loci），对72份雄性海枣种质材料的遗传多样性与种群结构展开了分析。共检测到125个等位基因（alleles），平均每个位点包含8.33个等位基因。基于贝叶斯模型的聚类分析显示，存在两个分化显著的特有雄性海枣遗传簇——大陆型与海岛型，同时还包含源自中东地区的引入种质材料。此前从未针对突尼斯海岛区域开展过海枣遗传多样性研究，本次分析发现该区域的种质资源蕴含极具价值的特有遗传材料，为"该区域存在野生海枣种质"的假说提供了有力支撑。
本研究结果对于筛选可纳入海枣（Phoenix dactylifera L.）国际协同育种项目的优良基因型，以及珍贵种质资源的保护与留存均具有关键意义。