Abstract Detail

Molecular Ecology and Evolution

Reynolds, Hannah [1], Barton, Hazel [2], Slot, Jason [3].

Re-duplication of nitrate reductase (NRT2) and dual nitrate response and in Pseudogymnoascus destructans, the White-nose Syndrome bat pathogen.

Pseudogymnoascus destructans, the causative agent of White-nose Syndrome (WNS), has been found both on bats and in cave sediments. The nitrate concentration of these sediments ranges over several orders of magnitude, and thus presents an environment in which dual nitrate uptake could be beneficial; adaptation to life in caves may have contributed to the emergence of P. destructans as a bat pathogen. While plants frequently have multiple nitrate transporters with varying affinities for nitrate, most fungi have only one high-affinity nitrate transporter. However, many fungi have been found to have two nitrate transporters, which permit both high affinity and high capacity nitrate uptake under different environmental conditions. We identified two nitrate transporter genes (NRT2) in the sequenced genome of P. destructans (Broad Institute) – one in a cluster with the nitrate and nitrite reductases and one unclustered on another scaffold -- suggesting P. destructans may have a dual-affinity nitrate uptake system. Remnants of the flanking genes near the unclustered NRT2, which was nearly identical in sequence to the clustered copy, led us to hypothesize this could be a recent duplication unique to P. destructans and a possible contributor to its shift to pathogenesis. To evaluate the evolutionary history of NRT2 in Pseudogymnoascus, we obtained 29 NRT2 sequences from 19 Pseudogymnoascus spp. genomes (15 from GenBank and 4 newly sequenced) and an additional 14 sequences from 7 strains by PCR. All examined species contained a clustered NRT2, with the cluster structure conserved throughout the genus, and 15 of the 26 non-pathogenic species contained a second, unclustered copy. The unclustered NRT2 sequences did not form a clade in phylogenetic analysis, suggesting multiple origins of dual-transporters in Pseudogymnoascus. A reconstruction of NRT2 duplications and losses compared to a multigene species phylogeny indicates the unclustered NRT2 in P. destructans is a very recent duplication, which followed the previous loss of an older unclustered copy. To test whether dual nitrate transporters enable dual nitrate transport capacities, we examined growth and nitrate metabolism of P. destructans in ten starting nitrate concentrations and found evidence of a dual nitrate response. This response may be beneficial for growth on bats, which excrete nitrogen-rich waste, and in cave sediments, which are low in organic nitrogen. Evolution of a more flexible nitrate uptake system may have increased P. destructans fitness in the cave/bat ecosystem and contributed to its emergence as a pathogen.

1 - The Ohio State University, Plant Pathology, 472 Kottman Hall, 2021 Co, Columbus, OH, 43210, USA
2 - University of Akron, Biology, 200 Carroll St, ASEC West Tower 178, Akron, OH, 44325, USA
3 - The Ohio State University, Plant Pathology, Columbus, OH, 43210, USA

Keywords:
White nose syndrome
nitrate
Pseudogymnoascus destructans
gene duplication
genomics
gene cluster.

Presentation Type: Oral Paper:Papers for Topics
Session: 61
Location: Salon 15/16/The Shaw Conference Centre
Date: Wednesday, July 29th, 2015
Time: 10:00 AM
Number: 61008
Abstract ID:1232
Candidate for Awards:Margaret Menzel Award