To map the distribution of feral oilseed rape (Brassica napus L.) in Japan, we conducted a roadside survey along 19 km of Route 51 for 10 years, from 2005 to 2014. We found more than 2,000 plants in the first 2 years. The number decreased to 150–305 from 2007 to 2010, and to only 27 in 2014, likely owing to extensive road repairs. Three areas of high frequency were found. One area features frequent hills. The second was where the road narrows, likely where seeds spill from trucks as they decelerate or accelerate. The third is in a fenced patch, showing that if spilled seeds fall in places where they cannot be managed, they can perpetuate. Our survey confirms that feral oilseed rape has nearly disappeared from this road. The proportion of genetically modified (GM) oilseed rape in the feral population was low, and it decreased as the total number of rape plants decreased. Therefore, we conclude that the distribution of GM oilseed rape growing along Route 51 has no effect on biodiversity such as suppression of other species' distribution and introgressive hybridization with wild relatives. This is the first report of a long‐term survey on the fate of oilseed rapes growing along transportation route in Japan.

中文翻译：

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沿日本路边生长超过10年的转基因油菜籽泄漏事件的发生

绘制野生油菜的分布图（甘蓝型油菜）L.）在日本，从2005年到2014年，我们沿着51号公路的19公里进行了为期10年的路边调查。在最初的2年中，我们发现了2,000多家工厂。从2007年到2010年，这一数字下降到150-305，而在2014年只有27个，这可能是由于道路维修的原因。发现了三个高频区域。一个地区经常出现丘陵。第二个是道路变窄的地方，很可能是种子在卡车减速或加速时从卡车溢出的地方。第三个在栅栏上，表明如果溢出的种子落在无法管理的地方，它们就会长存。我们的调查证实，野生油菜已经从这条路几乎消失了。转基因油菜在野生种群中的比例很低，并且随着油菜植株总数的减少而降低。因此，我们得出的结论是，沿51号公路生长的转基因油菜的分布对生物多样性没有影响，例如抑制其他物种的分布以及与野生近缘种的渐渗杂交。这是关于日本沿运输路线生长的油菜籽命运的长期调查的第一份报告。