Guarino1, A. Cicatelli1, G. Brundu2 and S. Castiglione1
1University of Salerno, Dept. of Chemistry and Biology “A. Zambelli”, Fisciano (SA), Italy
2University of Sassari, Dept. Agriculture, Sassari (SS), Italy
Giant reed (Arundo donax L.) has been introduced and grown for local uses in the Mediterranean region since ancient times. Common uses of giant reed include basket work, roofing, trellises, musical instruments and traditional medicine. More recently it has attracted the attention of European researchers and farmers as a potential non-food crop and for energy biomass production. As a result of this human-mediated spread, it is now widely naturalized in many areas of Europe, North and South America, Asia, Africa, Australia, New Zealand and in numerous islands across the Pacific (Mariani et al. 2010). Although well adapted to widely different ecological conditions, giant reed thrives in riparian habitats, where it forms dense monospecific stands. Flowers of its inflorescences are perfect, but neither pollen nor caryopsis have been documented in North America and in other parts of the invaded range (e.g. Europe). For this reason, it is considered a sterile plant, which spreads preferentially asexually through rhizomes at close proximity of the invaded area, and, very rarely, sexually (Bell 1997). Vegetative reproduction is expected to reduce the genetic biodiversity because of absence of meiotic mechanisms and, in particular, of its fundamental steps such as: crossing over, gene recombination and random chromosome assortment. Nevertheless, giant reed thrives very well in a large array of pedo-climatic conditions around the world, showing different phenotypic and phenological features, competing with many native species and displacing native vegetation and arthropod fauna in the invaded sites. This ability to adapt morphologically or physiologically to a broad array of conditions could be attributed to epigenetic mechanisms (Pilu et al. 2014). To shed light on this relevant issue, 96 stems of giant reed from spontaneous populations distributed across the Italian invaded range (island of Sardinia, Northern and Southern Italy) were analysed. Leaf DNAs were extracted and processed through Amplified Fragment Length Polymorphisms (AFLPs) and Methylation Sensitive Amplified Polymorphisms (MSAPs) for defining either genetic or epigenetic profiles, respectively. The AFLP results showed an extremely low genetic biodiversity within and among the studied populations due to vegetative reproduction, whilst, epi-biodiversity, estimated through MSAPs, increased. Our results suggests that the ability of giant reed to invade and thrive in diverse environmental conditions can be attributed, at least in part, to a higher epigenetic variability (Guarino et al. 2019). Moreover, in our opinion, the MSAP technique represents an efficient and cost-effective tool with which is possible to estimate epi-biodiversity of species and populations. As such, the epigenetic profiles should be considered and added to those commonly employed in the framework of the Convention on Biological Diversity. We foresee that epigenetic profiling could be determined in a similar way to genetic profiling, using the same indices, or developing new ones, but by processing DNAs separately based on methylation-sensitive and insensitive profiles. Therefore, we are convinced that the investigation of the DNA methylation status is fundamental for basic ecological and biodiversity studies, particularly in the case of plant species that preferentially propagate vegetatively.
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Guarino F., Cicatelli A., Brundu G., Improta G., Triassi M. & Castiglione S. (2019) The use of MSAP reveals epigenetic diversity of the invasive clonal populations of Arundo donax L. PLoS ONE 14: e0215096.
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