High-Throughput Sequencing Shows High Fungal Diversity and Community Segregation in the Rhizospheres of Container-Grown Conifer Seedlings

Abstract

Forest nurseries in Sweden produce ca. 360 million seedlings of Pinus sylvestris L. and Picea abies (L.) Karst. annually. Fungi represent the largest microbial component in rhizospheres and may significantly affect health and, consequently, quality of the seedlings. The aim of this study was to assess fungi focusing on pathogens in roots and the sphagnum peat growth substrate of healthy-looking P. sylvestris and P. abies seedlings from nine forest nurseries situated in northern, central and southern regions of Sweden. We hypothesized that nursery stock and the growth substrate can provide a venue for dissemination of fungal diseases. In each nursery and for each tree species, 100 seedlings with the growth substrate were collected during the dormant period. DNA was isolated from parts of root systems and from samples of the growth substrate, amplified using internal transcribed spacer of rDNA as a marker and 454-sequenced. Clustering at 98.5% similarity of 169,844 high-quality sequences resulted in 619 non-singleton fungal taxa. Although results showed that management practices in forest nurseries generally give a healthy stock, latent establishment of pathogenic fungi in both roots and the growth substrate supported the hypothesis. Furthermore, seedling roots and the growth substrate were inhabited by distinct communities of fungi, and lifestyles of these fungi largely determined community segregation into particular ecological niche.

Diplodia Tip Blight on Its Way to the North: Drivers of Disease Emergence in Northern Europe

“…Isolated trees showing severe symptoms were found in the immediacy of the outbreak, but those seem to fit better as part of the natural spread from the main stand, than as part of a widespread introduction. Recent surveys on spruce and pine seedlings in Sweden have not detected the pathogen (Menkis et al., 2016), so it seems that the current risk of D. sapinea being spread all over Sweden is rather low, although further surveys on the areas where seedlings from the same batch used in the outbreak area were planted should be undertaken.…”

Composition and Diversity of Soil Fungi in Dipterocarpaceae-Dominated Seasonal Tropical Forests in Thailand

“…A Cryptococcus species showed a significant preference for DEF plots, but was also detected in many DDF and FPDDF plots ( Table 2 ). Cryptococcus (OTU_718) was previously reported in various habitats, such as boreal forest soil in the Czech Republic ( 63 ), pine forest soil in the Netherlands ( 47 ), agricultural field soil in the UK ( 1 ), mycorrhizal roots in Germany ( 38 ), conifer mycorrhizal roots in Sweden ( 30 ), and agricultural soils in Michigan, USA ( 27 ). We also found that a fungus in Leohumicola , which includes heat-resistant fungi ( 18 ), showed a preference for DEF plots, although the biased distribution was not explained by the long-term frequency of forest fires (annual forest fires in DDF vs. no forest fires for >100 years in DEF) in Sakaerat.…”

Susceptibility of Several Northeastern Conifers to Fusarium circinatum and Strategies for Biocontrol

“…Moreover, they did not find any effect of F. circinatum on seedling emergence either. This outcome takes on greater relevance taking into account that P. abies, together with P. sylvestris, is the conifer more produced by the forest nurseries and planted in Central and Northern Europe [50,51].…”