Beghè D, Piotti A, Satovic Z, de la Rosa R, Belaj A
Department of Food Science, Parco Area delle Scienze, 95/a, 43124 Parma, Italy.
Institute of Tree and Timber (IVALSA), Italian National Research Council (CNR), Via Madonna del Piano 10, 50019 Sesto Fiorentino (FI), Italy.
Ann Bot. 2017 Mar 1;119(4):671-679. doi: 10.1093/aob/mcw246.
Wild olive ( Olea europaea subsp. europaea var. sylvestris ) is important from an economic and ecological point of view. The effects of anthropogenic activities may lead to the genetic erosion of its genetic patrimony, which has high value for breeding programmes. In particular, the consequences of the introgression from cultivated stands are strongly dependent on the extent of gene flow and therefore this work aims at quantitatively describing contemporary gene flow patterns in wild olive natural populations.
The studied wild population is located in an undisturbed forest, in southern Spain, considered one of the few extant hotspots of true oleaster diversity. A total of 225 potential father trees and seeds issued from five mother trees were genotyped by eight microsatellite markers. Levels of contemporary pollen flow, in terms of both pollen immigration rates and within-population dynamics, were measured through paternity analyses. Moreover, the extent of fine-scale spatial genetic structure (SGS) was studied to assess the relative importance of seed and pollen dispersal in shaping the spatial distribution of genetic variation.
The results showed that the population under study is characterized by a high genetic diversity, a relatively high pollen immigration rate (0·57), an average within-population pollen dispersal of about 107 m and weak but significant SGS up to 40 m. The population is a mosaic of several intermingled genetic clusters that is likely to be generated by spatially restricted seed dispersal. Moreover, wild oleasters were found to be self-incompatible and preferential mating between some genotypes was revealed.
Knowledge of the within-population genetic structure and gene flow dynamics will lead to identifying possible strategies aimed at limiting the effect of anthropogenic activities and improving breeding programmes for the conservation of olive tree forest genetic resources.
野生油橄榄（油橄榄欧洲亚种欧洲变种野生油橄榄）在经济和生态方面都很重要。人为活动的影响可能导致其遗传遗产的基因侵蚀，而这些遗传遗产对育种计划具有很高的价值。特别是，来自人工林渗入的后果在很大程度上取决于基因流的程度，因此这项工作旨在定量描述野生油橄榄自然种群中当代的基因流模式。
所研究的野生种群位于西班牙南部一片未受干扰的森林中，该森林被认为是现存为数不多的真正野生油橄榄多样性热点地区之一。通过八个微卫星标记对来自五棵母树的总共225棵潜在父本树和种子进行了基因分型。通过父系分析测量了当代花粉流水平，包括花粉迁入率和种群内部动态。此外，还研究了精细尺度的空间遗传结构（SGS）程度，以评估种子和花粉传播在塑造遗传变异空间分布中的相对重要性。
结果表明，所研究的种群具有高遗传多样性、相对较高的花粉迁入率（0·57）、种群内花粉平均传播距离约为107米以及在40米范围内较弱但显著的SGS。该种群是由几个相互交织的遗传簇组成的镶嵌体，这可能是由空间受限的种子传播产生的。此外，发现野生油橄榄具有自交不亲和性，并揭示了某些基因型之间的优先交配现象。
了解种群内的遗传结构和基因流动态将有助于确定可能的策略，以限制人为活动的影响，并改进橄榄树林遗传资源保护的育种计划。
