Fungal Diversity in the Phyllosphere of Pinus heldreichii H. Christ—An Endemic and High-Altitude Pine of the Mediterranean Region

Abstract

Pinus heldreichii is a high-altitude coniferous tree species naturaly occurring in small and disjuncted populations in the Balkans and southern Italy. The aim of this study was to assess diversity and composition of fungal communities in living needles of P. heldreichii specifically focusing on fungal pathogens. Sampling was carried out at six different sites in Montenegro, where 2-4 year-old living needles of P. heldreichii were collected. Following DNA isolation, it was amplified using ITS2 rDNA as a marker and subjected to high-throughput sequencing. Sequencing resulted in 31,831 high quality reads, which after assembly were found to represent 375 fungal taxa. The detected fungi were 295 (78.7%) Ascomycota, 79 (21.0%) Basidiomycota and 1 (0.2%) Mortierellomycotina. The most common fungi were Lophodermium pinastri (12.5% of all high-quality sequences), L. conigenum (10.9%), Sydowia polyspora (8.8%), Cyclaneusma niveum (5.5%), Unidentified sp. 2814_1 (5.4%) and Phaeosphaeria punctiformis (4.4%). The community composition varied among different sites, but in this respect two sites at higher altitudes (harsh growing conditions) were separated from three sites at lower altitudes (milder growing conditions), suggesting that environmental conditions were among major determinants of fungal communities associated with needles of P. heldreichii. Trees on one study site were attacked by bark beetles, leading to discolouration and frequent dieback of needles, thereby strongly affecting the fungal community structure. Among all functional groups of fungi, pathogens appeared to be an important component of fungal communities in the phyllosphere of P. heldreichii, especially in those trees under strong abiotic and biotic stress.

Patterns of Fungal Diversity in Needles, Rootlets and Soil of Endemic Pinus Peuce

“…Besides, it has been recently reported as one of the most abundant needle pathogens in high-altitude P. heldreichii forests in Montenegro (Lazarević and Menkis 2020), showing that it is not restricted by harsh environmental conditions prevailing in these habitats. Sydowia symptoms include needle discoloration, necrosis and shoot dieback.…”

“…Fungi play key roles in montane forest ecosystems and represent an essential part of biodiversity (Baldrian 2017;Lazarević and Menkis 2020). They directly in uence several physiological processes in trees and contribute to carbon, nutrient and water cycling (Stewart et al 2018).…”

“…. Surveys on the aboveground sporocarp production and analyses of ne roots have shown that Suillus granulatus is the dominant fungus in P. heldreichii forests in Montenegro(Lazarević et al 2011;Lazarević and Menkis 2018). In the present study, S. granulatus was only at the Visitor site, where P. heldreichii forest is in near proximity (see above) Liao et al (2016).…”

Fungal Diversity in the Mediterranean Area

“…Lazarević and Menkis also highlight how the phyllosphere is expressive of high species diversity. In the case study of the phyllosphere of the endemic forest tree Pinus heldreichii H.Christ., a huge number of fungal species were isolated, and mainly constituted Ascomycota [5]. The variability of the fungal community detected at different study sites and altitudes highlights the influence of environmental conditions on the presence/absence of fungal species.…”

New data on the spread of the invasive species Dothistroma septosporum (Dorogin) M. Morelet in Belarus

“…Согласно некоторым литературным источникам, N. germanicum отмечается на соснах, в доминирующей или сопутствующей микрофлоре которых присутствует Dothistroma spp. [31,33]. В данной работе возбудители дотистромоза (DNB) и коричневого пятнистого ожога (BSNB) генетически не были выявлены как в доминирующей, так и в сопутствующей микрофлоре исследуемых экземпляров сосны черной.…”