Abstract
Research Highlights: Protected natural areas are a reservoir of Phytophthora species and represent the most suitable sites to study their ecology, being less disturbed by human activities than other environments. Background and Objectives: The specific objective of this study was to correlate the diversity and distribution of Phytophthora species with the vegetation in aquatic, riparian and terrestrial habitats within a protected area in Eastern Sicily, Southern Italy. Materials and Methods: Environmental samples (water and soil) were sourced from two streams running through the reserve and six different types of vegetation, including Platano-Salicetum pedicellatae, the Sarcopoterium spinosum community, Myrto communis-Pistacietum lentisci, Pistacio-Quercetum ilicis,Oleo-Quercetum virgilianae and a gallery forest dominated by Nerium oleander (Natura 2000 classification of habitats). Phytophthora species were recovered from samples using leaf baiting and were classified on the basis of morphological characteristics and sequencing of internal transcribed spacer (ITS) regions of ribosomal DNA (rDNA). Results: As many as 11 Phytophthora species, within five different ITS clades, were identified, including P. asparagi, P. bilorbang, P. cryptogea, P. gonapodyides, P. lacustris, P. multivora, P. nicotianae, P. oleae, P. parvispora, P. plurivora and P. syringae. No Phytophthora species were found in the Sarcopoterium spinosum comm. Phytophthora asparagi, P. lacustris and P. plurivora were the prevalent species in the other five plant communities, but only P. plurivora was present in all of them. Overall aquatic species from clade 6 (100 out of 228 isolates) were the most common; they were recovered from all five types of vegetation, streams and riparian habitats. Phytophthora populations found in the Platano-Salicetum pedicellatae and Oleo-Quercetum virgilianae show the highest diversity, while no correlation was found with the physicochemical characteristics of the soil. Conclusions: The vegetation type and the aquatic or terrestrial habitat were identified as major environmental factors correlated with the diversity of Phytophthora communities in this reserve.
Highlights
The genus Phytophthora (Pythiaceae, Peronosporales, Oomycota, Chromista) comprises to date over 180 described species while, according to a conservative estimate, the actual number of species in this genus is at least double, if not triple [1,2]
Morphological and internal transcribed spacer (ITS) sequence analyses revealed the occurrence of multiple Phytophthora species in each type of plant community with the only exception of the Sarcopoterium spinosum vegetation, where no Phytophthora species was detected
Matched with 99–100% identity reference sequences of 11 known Phytophthora species belonging to five different ITS clades
Summary
The genus Phytophthora (Pythiaceae, Peronosporales, Oomycota, Chromista) comprises to date over 180 described species while, according to a conservative estimate, the actual number of species in this genus is at least double, if not triple [1,2]. A more restricted number of species in the phylogenetic ITS clade 6 recovered from water courses, lakes and irrigation basins are functionally more adapted to aquatic habitats [17,18,19,20,21]. These aquatic Phytophthora species are weakly aggressive as plant pathogens and, it has been assumed they behave as saprotrophs in plant debris in water and as opportunistic pathogens in riparian habitats. Their ecological role in ecosystems is not fully understood
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