Filamentous Ascomycetes Inhabiting the Rhizoid Environment of the Liverwort Cephaloziella varians in Antarctica Are Assessed by Direct PCR and Cloning

Abstract

We molecularly assesed the ascomycetous fungal communities inhabiting the rhizoid environment of Cephaloziella varians, collected at Rothera Point on the western Antarctic Peninsula. The RFLP-phenotyped and cloned PCR products of a partial small subunit of the ribosomal RNA gene were sequenced and analyzed with neighbor joining (NJ) and maximum parsimony (MP). Both analyses identified four bootstrap-supported groups: (i) a sister group to Onygenales, (ii) a well-supported clade with Phialocephala fortinii, (iii) a large group of clones nested within Chaetothyriales, and (iv) a group nested within Eurotiales with a likely affinity to the genus Aspergillus. An additional marginally supported clade, including helotialean Hymenoscyphus fructigenus, was detected in the NJ analysis. Placement of one clone (possibly helotialean) was not supported by either analysis. We included Hymenoscyphus ericae (Helotiales) in our analyses to test for its presence in clone libraries. None of our clones showed strongly supported affinity to H. ericae. The culture-independent technique proved useful for assessing the composition of rhizoid fungal communities, although it remains unknown whether any of these fungi colonize C. varians tissues. Direct-community assays of this kind might be best combined with traditional isolation techniques to get a more holistic view of fungi occupying plant tissues.