Mycorrhizal associations of the exotic hickory trees, Carya laciniosa and Carya cordiformis, grown in Kórnik Arboretum in Poland

Abstract

We studied mycorrhizal associations of North American Carya laciniosa and Carya cordiformis trees, successfully acclimated to local habitat conditions of the historic Kórnik Arboretum in Poland, in order to better understand mycorrhizal host range extensions in new environments. The root systems of Carya seedlings (1–3 years old), regenerated under a canopy of mature hickory trees, were analyzed using microscopic, morphological, and molecular techniques. Our results, for the first time, indicate that C. laciniosa and C. cordiformis have both arbuscular and ectomycorrhizal associations. In the cleared and stained roots of both Carya species, typical structures of arbuscular mycorrhizae (vesicles, arbuscules, hyphal coils, and intercellular nonseptate hyphae) were detected. On the basis of ITS rDNA sequencing, 40 ectomycorrhizal fungal taxa were revealed, with 25 on C. laciniosa and 19 on C. cordiformis. Only four fungal species (Cenococcum geophilum sensu lato, Russula recondita, Xerocomellus cisalpinus, Humaria hemisphaerica) were shared by both Carya species. The high number of infrequent fungal taxa found, as well as the calculated richness estimator, indicates that the real ectomycorrhizal community of C. laciniosa and C. cordiformis is probably richer. The ability of the exotic Carya species to form arbuscular and ectomycorrhizal linkages with native fungi could be a factor in the successful establishment of these tree species under the conditions of Kórnik Arboretum.Electronic supplementary materialThe online version of this article (10.1007/s00572-018-0846-8) contains supplementary material, which is available to authorized users.

The Limited Establishment of Native Ectomycorrhizal Fungi in Exotic Eucalyptus spp. Stands in Japan

“…We presume that differences in the results obtained for Oji Zoo and the Botanical Gardens might be attributed to the presence/absence of infection via mycelial networks shared between eucalyptus and native hosts, given that eucalyptus and native hosts grow in close proximity in the Botanical Gardens, but not in Oji Zoo. High infection rates in exotic hosts, as well as infection of exotic hosts by native ECM fungi, have also been reported previously in mixed forests composed of both native and exotic hosts (Jairus et al, 2011;Pennington et al, 2011;Moeller et al, 2015;Rudawska et al, 2018;Santolamazza-Carbone et al, 2019). Especially, Santolamazza-Carbone et al (2019) reported lower infection rates and ECM fungal richness of eucalyptus growing inside the eucalyptus plantations than inside the natural forests, which is in line with our results.…”

“…Previous studies are generally conducted in forests where native and exotic tree species grow together to a greater or lesser extent. Although some native ECM fungi have been reported to infect exotic host species in such mixed-stand forests ( Bahram et al, 2013 ; Rudawska et al, 2018 ; Santolamazza-Carbone et al, 2019 ), caution should be exercised in interpreting these results, as the host ranges of ECM fungi could be broadened in areas where multiple host plants are growing together, owing to infection via common mycelial networks ( Smith et al, 1995 ; Suz et al, 2017 ). If this hypothesis is true, it is unclear whether ECM fungi associated with exotic hosts in mixed forests are able to establish an association with novel host plant species in areas where their original host plants are absent.…”

Rhizobium Presence and Functions in Microbiomes of Non-leguminous Plants

“…Facultative dual mycorrhizal symbiosis is considered to be the plant's ability to establish the different types of mycorrhizal associations in response to environmental conditions or plant age. For example, the predominance of ectomycorrhizal and presence of arbuscular structures have been examined for Quercus rubra seedlings inside its native range and Carya seedling outside its native range in Europe (Rudawska et al 2018), where Q. rubra (Fagaceae, Fagales) is invasive species but Carya species (Juglandaceae, Fagales) are naturalized and still grown on the old European plantations abandoned for a half of a century (Paź et al 2018;Wilgan et al 2020). The general proportion of plant species that have naturalized outside their native range is significantly higher for plants entering the mycorrhizal symbiosis facultatively (76%) than obligatorily (52%).…”

“…Both arbuscular and ectomycorrhizal fungal species may belong to commonly occurring generalists/cosmopolitans and to the specialists, whose occurrence is limited by several environmental, geographical, or physiological factors. Up to now, more studies describing fungal communities have been concentrated on ectomycorrhizal fungi associated with woody species in natural conditions, nurseries, or at disturbed areas (e.g., Karliński et al 2013;Leski et al 2019;Rudawska et al 2018Rudawska et al , 2019. Communities of arbuscular fungi, despite their widespread occurrence, were thought to be less diverse .…”

Mycorrhizal symbiosis of alien and invasive tree species

“…the hickories growing in european forests do not exhibit the characteristics of invasive species (Tokarska-Guzik et al 2012;Paź et al 2018), and the ectomycorrhizal fungi communities associating with themare formed exclusively by european fungi species, the majority (90%) of which are oak symbionts. these communities are characterised by high diversity (about 100 species) (Rudawska et al 2018b; wilgan et al 2019), comparable to and even higher than the diversity of ectomycorrhizal fungi in native oak-hornbeam forests (Wilgan et al 2019). Perhaps this reflects the assumptions of the degraded mutualismhypothesis, wherein alien species that have become invasive (such as red oak) would become symbiotic with fewer fungal species and be less dependent on symbiosis than non-invasive alien species such as hickories.…”