Ectomycorrhizal fungi in Mexican Alnus forests support the host co-migration hypothesis and continental-scale patterns in phylogeography

Abstract

To examine the geographic patterns in Alnus-associated ectomycorrhizal (ECM) fungal assemblages and determine how they may relate to host plant biogeography, we studied ECM assemblages associated with two Alnus species (Alnus acuminata and Alnus jorullensis) in montane Mexico and compared them with Alnus-associated ECM assemblages located elsewhere in the Americas. ECM root samples were collected from four sites in Mexico (two per host species), identified with ITS and LSU rRNA gene sequences, and assessed using both taxon- (richness, diversity, evenness indices) and sequence divergence-based (UniFrac clustering and significance) analyses. Only 23 ECM taxa were encountered. Clavulina, an ECM lineage never before reported with Alnus, contained the dominant taxon overall. ECM assemblage structure varied between hosts, but UniFrac significance tests indicated that both associated with similar ECM lineage diversity. There was a strikingly high sequence similarity among a diverse array of the ECM taxa in Mexico and those in Alnus forests in Argentina, the United States, and Europe. The Mexican and United States assemblages had greater overlap than those present in Argentina, supporting the host-ECM fungi co-migration hypothesis from a common north temperate origin. Our results indicate that Alnus-associated ECM assemblages have clear patterns in richness and composition across a wide range of geographic locations. Additional data from boreal western North America as well as the eastern United States and Canada will be particularly informative in further understanding the co-biogeographic patterns of Alnus and ECM fungi in the Americas.

Enigmatic Sebacinales

“…As in Pinaceae and Fagaceae, sebacinalean ECMs are present in Japanese mixed forests on Betula maximowicziana, B. grossa, and Carpinus japonica (Ishida et al 2007). Studies of ECMs in Mexican Alnus forests, supporting the host co-migration hypothesis, also included sebacinalean fungi (Kennedy et al 2011).…”

How Ectomycorrhizae Structures Boost the Root System?

“…Later studies by Á gueda et al (2010), Buée et al (2009), De Román andDe Miguel (2005), García-Barreda and Reyna (2012), Genney et al (2006), Kennedy et al (2011a), Pickles et al (2010), Põlme et al (2013), Pritsch et al (2010), and Roy et al (2013) have confirmed this fact.…”

“…Recent studies about the ectomycorrhizal fungal communities in alder forests on a local scale (Pritsch et al 2010), regional scale (Kennedy et al 2011a;Roy et al 2013), and global scale (Põlme et al 2013) show that they are not primarily rich, regardless of sampling intensity. The special characteristics of the Alnus spp.…”

Mycorrhizal detection of native and non-native truffles in a historic arboretum and the discovery of a new North American species, Tuber arnoldianum sp. nov.

“…The thermocycler program was set for 94°C for 3 min (initiation and denaturation) followed by 35 cycles of 94°C for 1 min (denaturation), 50°C for 45 s (annealing), 72°C for 1.5 min (extension), with a final extension time of 10 min at 72°C. To verify the host of the sampled EcM roots, the primers trnL-c and trnL-d were used to amplify a region of the chloroplast DNA (Taberlet et al 1991) on amplified root tips for each tree sampled, following thermocycler conditions of Kennedy et al (2011). Amplification of DNA was confirmed by electrophoresis on 1 % agarose gels and visualized with GelRed (Biotium, Hayward, CA) under UV light.…”