Tehseen Muhammad Massub, Tonk Fatma Aykut, Tosun Muzaffer, Istipliler Deniz, Amri Ahmed, Sansaloni Carolina P, Kurtulus Ezgi, Mubarik Muhammad Salman, Nazari Kumarse
Department of Field Crops, Ege University, Bornova, Turkey.
ICARDA-PreBreeding and Genebank Operations, Biodiversity and Crop Improvement Program, Rabat, Morocco.
Front Genet. 2022 Jun 15;13:900572. doi: 10.3389/fgene.2022.900572. eCollection 2022.
Landraces are considered a valuable source of potential genetic diversity that could be used in the selection process in any plant breeding program. Here, we assembled a population of 600 bread wheat landraces collected from eight different countries, conserved at the ICARDA's genebank, and evaluated the genetic diversity and the population structure of the landraces using single nucleotide polymorphism (SNP) markers. A total of 11,830 high-quality SNPs distributed across the genomes A (40.5%), B (45.9%), and D (13.6%) were used for the final analysis. The population structure analysis was evaluated using the model-based method (STRUCTURE) and distance-based methods [discriminant analysis of principal components (DAPC) and principal component analysis (PCA)]. The STRUCTURE method grouped the landraces into two major clusters, with the landraces from Syria and Turkey forming two clusters with high proportions of admixture, whereas the DAPC and PCA analysis grouped the population into three subpopulations mostly according to the geographical information of the landraces, i.e., Syria, Iran, and Turkey with admixture. The analysis of molecular variance revealed that the majority of the variation was due to genetic differences within the populations as compared with between subpopulations, and it was the same for both the cluster-based and distance-based methods. Genetic distance analysis was also studied to estimate the differences between the landraces from different countries, and it was observed that the maximum genetic distance (0.389) was between the landraces from Spain and Palestine, whereas the minimum genetic distance (0.013) was observed between the landraces from Syria and Turkey. It was concluded from the study that the model-based methods (DAPC and PCA) could dissect the population structure more precisely when compared with the STRUCTURE method. The population structure and genetic diversity analysis of the bread wheat landraces presented here highlight the complex genetic architecture of the landraces native to the Fertile Crescent region. The results of this study provide useful information for the genetic improvement of hexaploid wheat and facilitate the use of landraces in wheat breeding programs.
地方品种被认为是潜在遗传多样性的宝贵来源，可用于任何植物育种计划的选择过程。在这里，我们收集了600份从八个不同国家采集的面包小麦地方品种，保存在国际干旱地区农业研究中心（ICARDA）的基因库中，并使用单核苷酸多态性（SNP）标记评估了这些地方品种的遗传多样性和群体结构。总共11830个分布在A基因组（40.5%）、B基因组（45.9%）和D基因组（13.6%）的高质量SNP用于最终分析。使用基于模型的方法（STRUCTURE）和基于距离的方法[主成分判别分析（DAPC）和主成分分析（PCA）]对群体结构进行评估。STRUCTURE方法将地方品种分为两个主要聚类，来自叙利亚和土耳其的地方品种形成两个具有高比例混合的聚类，而DAPC和PCA分析主要根据地方品种的地理信息将群体分为三个亚群，即叙利亚、伊朗和土耳其的混合群体。分子方差分析表明，与亚群间相比，大部分变异是由于群体内的遗传差异造成的，基于聚类和基于距离的方法都是如此。还进行了遗传距离分析以估计不同国家地方品种之间的差异，观察到最大遗传距离（0.389）存在于来自西班牙和巴勒斯坦的地方品种之间，而最小遗传距离（0.013）存在于来自叙利亚和土耳其的地方品种之间。研究得出结论，与STRUCTURE方法相比，基于模型的方法（DAPC和PCA）能够更精确地剖析群体结构。这里展示的面包小麦地方品种的群体结构和遗传多样性分析突出了新月沃地地区地方品种复杂的遗传结构。本研究结果为六倍体小麦的遗传改良提供了有用信息，并促进了地方品种在小麦育种计划中的应用。
