Genetic variability in landraces populations and the risk to lose genetic variation. The example of landrace ‘Kyperounda’ and its implications for ex situ conservation

Genetic characterization enhances the development of rational conservation strategies and the utilization of germplasm to plant breeding programs. In the present study, 19 microsatellite markers were employed to evaluate the genetic diversity and the genetic affiliations across 20 Cypriot durum wheat (Triticum turgidum L. subsp. durum) landraces, 13 landraces from the broader Mediterranean basin and 22 modern varieties. Cluster analysis depicted a clear separation among modern varieties and landraces, regardless of their origin. Landraces presented the highest genetic variation (average discriminating power of 0.89) and a high number of private alleles (131) was detected; underlying the unique genetic mark-up of this genepool. AMOVA revealed that the highest variability was detected within the landraces originating from Cyprus and landraces from the broader Mediterranean basin. The Cypriot landrace ‘Kyperounda’ was selected for further evaluation of its’ intra-genetic variation and it was determined that genetic diversity was higher in accessions conserved as sublines (He 0.643–0.731) than bulks (He 0.384–0.469). Bayesian analysis revealed substantial admixture within ‘Kyperounda’ accessions, depicted also by Principal Coordinate Analysis. The findings of the current manuscript emphasize that high intra-genetic diversity is retained when landraces are conserved as sublines in ex situ collections, while landraces that are conserved as bulks have a higher risk of bottleneck. Hence, a more exhausting diversity evaluation is needed in order to fully utilize landraces in breeding schemes and to prevent the loss of genetic variation.遗传表征有助于制定合理的保育策略，并推动种质资源在植物育种项目中的应用。本研究采用19个微卫星标记（microsatellite markers），对20份塞浦路斯硬粒小麦（Triticum turgidum L. subsp. durum）地方品种、13份来自地中海周边区域的地方品种以及22个现代品种的遗传多样性与遗传亲缘关系进行了评估。聚类分析结果显示，无论起源地如何，现代品种与地方品种均呈现出清晰的区分。地方品种展现出最高的遗传变异水平（平均鉴别力为0.89），且检测到131个私有等位基因，这凸显了该基因库独特的遗传构成。分子方差分析（AMOVA）结果显示，塞浦路斯地方品种与地中海周边区域地方品种内部的变异程度最高。研究选取塞浦路斯地方品种‘Kyperounda’开展进一步的居群内遗传变异评估，结果发现，以亚系形式保存的种质材料的遗传多样性（期望杂合度He为0.643~0.731）高于以混合群体形式保存的种质材料（He为0.384~0.469）。贝叶斯分析结果显示，‘Kyperounda’的种质材料内部存在显著的遗传混合现象，这一结果也通过主坐标分析得到了验证。本研究结果表明，若将地方品种以亚系形式保存于非原生境种质库中，可保留较高的居群内遗传多样性；而以混合群体形式保存的地方品种则面临更高的瓶颈效应风险。因此，为充分将地方品种应用于育种方案，并避免遗传变异流失，亟需开展更为详尽的多样性评估工作。