The Role of Pathogens in Plant Invasion: Accumulation of Local Pathogens Hypothesis

In the past decades, dozens of invasion hypotheses have been proposed to elucidate the invasion mechanisms of exotic species. Among them, the accumulation of local pathogens hypothesis (ALPH) posits that invasive plants can accumulate local generalist pathogens that have more negative effect on native species than on themselves; as a result, invasive plants might gain competitive advantages that eventually lead to their invasion success. However, research on this topic is still quite insufficient. In this context, we performed a comprehensive literature survey in order to provide a detailed description of the origin and theoretical framework of ALPH; in addition, challenges in contemporary research such as limitations in technical methods and the complexity of interactions between plants and soil microorganisms, as well as future directions of ALPH research, are also discussed in this review. So far, there are less than ten case studies supporting ALPH; therefore, more work is needed to demonstrate whether ALPH is a suitable hypothesis to elucidate the invasion success of certain plant species.