Evolutionary Relationships of Native New Zealand Lycopodiaceae and their Endospheric Microbial Associations

Abstract

The Lycopodiaceae, or clubmosses, are an ancient family of vascular land plants that is sister to all other vascular plant linages. Despite the family’s evolutionary significance, the relationships of its 400 species are poorly understood and no phylogeny including all 11 of New Zealand’s native species has been published. Additionally, there has been little research into the microbial communities present in Lycopodiaceae roots. These communities, including arbuscular mycorrhizal (AM) fungi, were vital to the initial expansion of plants into terrestrial environments and New Zealand Lycopodiaceae species have not previously been included in such investigations. In this study, the global relationships of all the New Zealand Lycopodiaceae species were determined for the first time through chloroplast rbcL sequencing and phylogeny reconstruction. Several New Zealand species showed infraspecific genetic variation both within New Zealand and/or compared to conspecific sequences from overseas. Additionally, the endospheric composition and biodiversity of New Zealand Lycopodiaceae microbial communities was measured for the first time using Next-Generation Sequencing. Species-specific endosphere community composition was observed as well as common general fungi and bacteria combinations colonizing all species of New Zealand Lycopodiaceae. Collectively, the microbial communities found in New Zealand Lycopodiaceae roots are comprised of Glomeromycota, Zygomycota, Rozellomycota, Ascomycota, Basidiomycota and bacteria, which on average make up 0.68%, 0.86%, 0.67%, 50.60%, 6.20% and 33.86% of the endosphere respectively. New Zealand Lycopodiaceae species associate with high numbers of Ascomycota fungi, which are thought to be plant pathogens, and high numbers of Alphaproteobacteria, a class of bacteria known for its nitrogen-fixing properties. No novel species of AM fungi were isolated however; orders of dark septate endophytes were retrieved. These results reveal the endospheric associations of one of the oldest families of vascular land plants, which could have shaped the evolution and expansion of lycophytes and therefore modern flora.