**1. Introduction**

Endophytic fungi are ubiquitous to plants, and are mainly members of Ascomycota or their mitosporic stage, but they also include some taxa of Basidiomycota, Zygomycota, and Oomycota. Endophytes are organisms living within the tissues of plants [1] establishing stable relationships with their host, ranging from non-pathogenic to beneficial [2,3]. The endophytic fungi communities represent an enormous reserve of biodiversity and constitute a rich source of bioactive compounds used in agriculture [4,5]. For these reasons, they have attracted the attention of the scientific community worldwide. By definition, all or at least a significant part of the endophytic fungi life cycle occurs within the plant tissues without causing symptoms to their host [6–8]. A wide range of fungi, including pathogens and saprophytes, may be endophytes. Several pathogens live asymptomatically within plant tissues during their latency or quiescent stage, while some saprobes can also be facultative parasites [1,8,9]. Fungal endophytes are influenced by abiotic and biotic factors, occupying different habitats and locations during their life cycle phases. Even if host plants do not show any symptoms, they may represent a source of inoculum for other species [10–13]. Furthermore, changes in environmental conditions or species hosts may modify the fungal behavior, thus producing disease symptoms [8,11,14]. Large quantities of plants and plant material that are globally traded

might contain asymptomatic infections of these fungi. It is generally accepted that the movement of plants and plant products by global trade and human activities is the most common way to introduce exotic pathogens and pests in non-endemic countries. Plant health is increasingly threatened by the introduction of emerging pests and/or pathogens [15,16]. Noticeable examples are represented by the invasion of alien plant pathogens into new areas [17–19]. Generally, biological invasions are the main threat to biodiversity [20], causing a decrease in species richness and diversity [20,21] or affecting local biological communities [22], as well as changing ecosystem processes [23–25].

In this scenario, the European Food Safety Authority (EFSA) Panel on Plant Health is responsible for the risk assessment, evaluations of risk reduction options, as well as guidance documents [26] in the domain of plant health for the European Union (EU) [26,27]. Commission Implementing Regulation (EU) [28] prohibits the importation of 35 so-called 'High-Risk Plants, plant products and other objects' from all third (non-EU) countries as long as no full risk assessment has been carried out. The EFSA Panel on Plant Health was requested to prepare and deliver risk assessments for these commodities [27,28], to evaluate whether the plant material will remain prohibited or removed from the list, with or without the application of additional measures [27,29]. The Commodity Risk Assessment has to be performed on the basis of technical dossiers provided by National Plant Protection Organizations of third countries. Information required for the preparation and submission of technical dossiers includes data on the pests potentially associated with the plant species or genera and on phytosanitary mitigation measures and inspections [30,31].

These plants have been identified as 'High-Risk Plants' by the EU since they 'host commonly hosted pests known to have a major impact on plant species which are of major economic, social or environmental importance to the Union' [28]. However, among these 35 plant genera, within the meaning of Art. 42 of Regulation (EU) 2016/2031, a list of only 13 taxa have been selected by the EFSA as plants mostly traded for ornamental purposes. According to this list, we have reviewed the following genera: *Acacia* Mill., *Albizia* Durazz., *Bauhinia* L., *Berberis* L., *Caesalpinia* L., *Cassia* L., *Cornus* L., *Hamamelis* L., *Jasminus* L., *Ligustrum* L., *Lonicera* L., *Nerium* L., and *Robinia* L. In this article, as much as possible, we highlight the potential risks associated with the movement of plants or materials among nations. Although other plant species may also have a significant impact, this review is limited to plants included in EU regulation [28] that do not originate within Europe. Thus, given these perspectives for future assessments, the present investigation offers an up-to-date snapshot of endophytic fungi associated with the so-called 'High-Risk Plants for ornamental purpose'. The aim is to facilitate the information required for technical dossiers, needed by the EFSA to perform the Commodity Risk Assessment of 13 plants mandated on an EU import list.
