Data from: ICE1 demethylation drives range expansion of a plant invader through cold-tolerance divergence

Cold tolerance of alien invasive plants is a crucial determinant for their establishment and expansion into new cold environments. A close relationship between cold-tolerance level of 34 populations represented by 147 accessions and latitude, extreme lowest temperature, coldest month average temperature and invasion age revealed that cold-tolerance divergence is a key factor driving the spreading of Ageratina adenophora, a highly invasive plant in China, to subtropical areas northeastward from the first-colonized southwestern region. Four epialles of cold response regulator ICE1 were found ranging from 66 to 50 methylated cytosines, representing a 4.4% to 3.3% methylation rate and significantly corresponded to the lowest to highest cold-tolerance levels among those different populations. A comparative study of four geographically-distinct populations firstly demonstrated that ICE1 demethylation upregulated transcription level of CBF transcription pathway is responsible for this evolution. Those facts, combined with the variation of colt-tolerance and methylation found among three native and two other introduced populations, indicate that demethylation of a gene upregulating cold tolerance may be the underlying evolutionary mechanism allowing crofton weed to expand northwards in China.

外来入侵植物的耐寒性是其成功定殖并扩散至低温新生境的关键决定因素。本研究针对以147份种质材料（accession）为代表的34个种群的耐寒性水平，与纬度、极端最低气温、冷月平均气温以及入侵时长之间的密切关联分析表明，耐寒性分化是驱动中国恶性入侵植物紫茎泽兰（Ageratina adenophora）从首次定殖的西南区域向东北方向亚热带区域扩散的关键因子。研究发现冷应答调控因子ICE1的4种表观等位基因（epiallele）的甲基化胞嘧啶数目介于66至50之间，对应甲基化率为4.4%至3.3%，且与不同种群从最低到最高的耐寒性水平显著相关。对4个地理分化种群的比较研究首次证实，ICE1基因的去甲基化可上调CBF转录通路的转录水平，这是该适应性演化的分子机制。结合在3个原生种群与另外2个引入种群中观测到的耐寒性与甲基化水平变异，上述结果表明：调控耐寒性的基因发生去甲基化，可能是紫茎泽兰得以在中国境内向北扩张的潜在演化机制。