Data from: Crop-to-wild gene flow and spatial genetic structure in the closest wild relatives of the cultivated apple

Crop-to-wild gene flow have important evolutionary and ecological consequences and require careful consideration in conservation programs for wild genetic resources of potential use in breeding programs and in assessments of the risk of transgene escape into natural ecosystems. Using 26 microsatellites and a set of 1181 trees, we investigated the extent of introgression from the cultivated apple, Malus domestica, to its three closest wild relatives, M. sylvestris in Europe, M. orientalis in the Caucasus and M. sieversii in Central Asia. We found footprints of introgression from M. domestica to M. orientalis (3.2% of hybrids), M. sieversii (14.8%) and M. sylvestris (36.7%). Malus sieversii and M. orientalis presented weak but significant genetic structures across their geographic range. Malus orientalis displayed genetic differentiation with three differentiated populations in Turkey, Armenia and Russia. Malus sieversii consisted of a main population spread over Central Asia and a smaller population in the Tian Shan Mountains. The low Sp values suggest high dispersal capacities for the wild apple relatives. High potential for crop-to-wild gene flow in apples needs to be considered in the implementation of in situ and ex situ actions for the conservation of wild apple genetic resources potentially useful to plant breeding.

作物向野生近缘种的基因流具有重要的进化与生态学意义，在针对具备育种应用潜力的野生遗传资源开展的保护计划，以及评估转基因逃逸至自然生态系统的风险时，均需审慎考量此类过程。本研究采用26个微卫星（microsatellite）标记，结合1181份苹果样本，探究了栽培苹果（Malus domestica）向其3个近缘野生类群的基因渐渗（introgression）程度，这三个野生类群分别为分布于欧洲的欧洲野苹果（Malus sylvestris）、高加索地区的东方苹果（Malus orientalis）以及中亚的塞威士苹果（Malus sieversii）。研究结果显示，栽培苹果向三个野生种的基因渐渗均存在痕迹：东方苹果的渐渗杂交个体占比为3.2%，塞威士苹果为14.8%，欧洲野苹果则高达36.7%。塞威士苹果与东方苹果在各自的地理分布范围内，均呈现出微弱但显著的遗传结构。其中东方苹果可被划分为3个遗传分化显著的种群，分别分布于土耳其、亚美尼亚与俄罗斯境内；塞威士苹果则包含一个广泛分布于中亚的主要种群，以及一个位于天山山脉的小型种群。较低的Sp统计量表明，这些苹果野生近缘种具备较强的扩散能力。苹果属作物向野生近缘种存在较高的基因流潜力，因此在针对具备植物育种应用价值的苹果野生遗传资源实施原地（in situ）与迁地（ex situ）保护工作时，需充分考量这一因素。