Data from: Crossing the divide: gene flow produces intergeneric hybrid in feral transgenic creeping bentgrass population

Gene flow is the most frequently expressed public concern related to the deregulation of transgenic events (Snow 2002; Ellstrand 2003). However, assessing the potential for transgene escape is complex because it depends on the opportunities for unintended gene flow, and establishment and persistence of the transgene in the environment (Warwick et al. 2008). Creeping bentgrass (Agrostis stolonifera L.), a turfgrass species widely used on golf courses, has been genetically engineered to be resistant to glyphosate, a nonselective herbicide. Outcrossing species, such as creeping bentgrass (CB), which have several compatible species, have greater chances for gene escape and spontaneous hybridization (i.e. natural, unassisted sexual reproduction between taxa in the field), which challenges transgene containment. Several authors have emphasized the need for evidence of spontaneous hybridization to infer the potential for gene flow (Armstrong et al. 2005). Here we report that a transgenic intergeneric hybrid has been produced as result of spontaneous hybridization of a feral-regulated transgenic pollen receptor (CB) and a nontransgenic pollen donor (rabbitfoot grass, RF, Polypogon monspeliensis (L.) Desf.). We identified an off-type transgenic seedling and confirmed it to be CB × RF intergeneric hybrid. This first report of a transgenic intergeneric hybrid produced in situ with a regulated transgenic event demonstrates the importance of considering all possible avenues for transgene spread at the landscape level before planting a regulated transgenic crop in the field. Spontaneous hybridization adds a level of complexity to transgene monitoring, containment, mitigation and remediation programmes.

基因流（gene flow）是与转基因事件（transgenic events）解禁相关的最受公众关切的议题（Snow，2002；Ellstrand，2003）。然而，评估转基因逃逸（transgene escape）的潜在风险较为复杂，因为其依赖于非预期基因流发生的概率，以及转基因在环境中的定植与存续能力（Warwick等，2008）。匍匐翦股颖（Creeping bentgrass, *Agrostis stolonifera* L.）是广泛应用于高尔夫球场的草坪草品种，经基因工程改造后可耐受非选择性除草剂草甘膦（glyphosate）。异交物种（outcrossing species）如匍匐翦股颖（CB）存在多个近缘兼容物种，因此更易发生基因逃逸与自然杂交（spontaneous hybridization）——即田间类群间无需人工辅助的自然有性生殖——这对转基因防控（transgene containment）构成挑战。多位学者均强调，需通过自然杂交的相关证据来推断基因流的潜在风险（Armstrong等，2005）。本研究报道了如下发现：野生状态下的已获批转基因花粉受体（CB，匍匐翦股颖）与非转基因花粉供体兔足草（rabbitfoot grass, RF, *Polypogon monspeliensis* (L.) Desf.）通过自然杂交，产生了转基因属间杂种（intergeneric hybrid）。我们发现了一株异常的转基因幼苗，并证实其为CB×RF属间杂种。本研究首次报道了在田间原位（in situ）环境下由获批转基因事件产生的转基因属间杂种，这一结果表明，在田间种植获批转基因作物前，需全面考量景观尺度（landscape level）下所有可能的转基因扩散途径。自然杂交为转基因监测、防控、减缓及修复项目增加了复杂度。