Hodgins, K. A., Lai, Z., Nurkowski, K., Huang, J. and Rieseberg, L. H. (2013), The molecular basis of invasiveness: differences in gene expression of native and introduced common ragweed (Ambrosia artemisiifolia) in stressful and benign environments. Molecular Ecology, 22: 2496–2510. doi: 10.1111/mec.12179

Although the evolutionary and ecological processes that contribute to plant invasion have been the focus of much research, investigation into the molecular basis of invasion is just beginning. Common ragweed (Ambrosia artemisiifolia) is an annual weed native to North America and has been introduced to Europe where it has become invasive. Using a custom-designed NimbleGen oligoarray, we examined differences in gene expression between five native and six introduced populations of common ragweed in three different environments (control, light stress and nutrient stress), as well as two different time points. We identified candidate genes that may contribute to invasiveness in common ragweed based on differences in expression between native and introduced populations from Europe. Specifically, we found 180 genes where range explained a significant proportion of the variation in gene expression and a further 103 genes with a significant range by treatment interaction. Several of these genes are potentially involved in the metabolism of secondary compounds, stress response and the detoxification of xenobiotics. Previously, we found more rapid growth and greater reproductive success in introduced populations, particularly in benign and competitive (light stress) environments, and many of these candidate genes potentially underlie these growth differences. We also found expression differences among populations within each range, reflecting either local adaptation or neutral processes, although no associations with climate or latitude were identified. These data provide a first step in identifying genes that are involved with introduction success in an aggressive annual weed.

尽管大量的研究集中在进化和生态过程在植物入侵方面的作用方面，然而对于入侵的分子基础的探索才刚刚开始。豚草（Ambrosia artemisiifolia）是北美洲一种本土一年生杂草显著已经被引入欧洲并且形成入侵。我们用定制的Nimblegen芯片比较了2个不同时间点5个本土种群和6个引入种群豚草在三种环境（对照、光胁迫和营养胁迫）下基因表达的差异。根据本地和来自欧洲的引入种群的表达差异我们找到了豚草入侵性相关的备选基因。具体来说，我们找到了分布范围能解释大部分表达差异的180个基因，和分布范围与处理的交互作用控制的103个基因。这些基因中有几个很可能与次生化合物代谢、胁迫响应和外源化学物质解毒相关。之前我们发现，尤其在营养条件好和有竞争压力（光胁迫）的环境下，引入的种群具有较高的生长速度和较大的繁殖成功；并且这些备选基因中的多数很可能导致了这些生长差异。虽然气候或维度与基因表达不相关，我们仍然发现每个分布范围内的种群内部的基因表达也有差异，这反映了局地适应或者中性过程。这些数据迈出了确定与一种破坏性很强的一年生杂草的引种成功相关基因的第一步。