The Mycorrhizal Communities of Lophomyrtus Bullata Burret (Myrtaceae) Within Three Natural Forest Associations of New Zealand

Abstract

Lophomyrtus bullata commonly known as ramarama, is a member of the Myrtaceae family. It is one of two endemic taxa (Lophomyrtus bullata and Lophomyrtus obcordata). Lophomyrtus is notable also in that it is one of New Zealand’s few endemic genera. Ramarama has recently been classified as a Threatened – Nationally Critical species because of the threat from myrtle rust (Austropuccinia psidii (G. Winter) Beenken). Mycorrhizal communities play an important role in the survival of plant species. It is important to understand these fungal communities and their effects on plant success, ecology, and resistance to disease; such knowledge works towards the improved management of plant species. This research looked at the mycorrhizal communities of Lophomyrtus bullata, in conjunction with the vegetation and location characteristics in the three forest associations: coastal, montane and cloud forest to understand how different environmental factors can influence its mycorrhizal communities in Northern New Zealand’s ecosystems. Root and soil samples were collected from each forest associations, and notes taken on the vegetation composition at each sample site. Microscopy and molecular work were undertaken on root samples and chemical analyses done on soils. Molecular sampling showed a diverse fungal community in association with L. bullata, including nine families of arbuscular mycorrhizae, the presence of this mycorrhizal type being further confirmed by microscopy. Other fungal groups also found in the sampling include Ascomycota, Basidiomycota and Zygomycota; the family Archaesporaceae is a particularly abundant and diverse arbuscular mycorrhiza in symbiosis with L. bullata. The species composition across vegetation associations is similar but their abundances differ. The Coastal location (Maunganui Bluff) is different in both mycorrhizal community and soil characters from the montane (Six-Foot Track) and Cloud Forest (The Domain) which are shown to be linked as they are similar in composition of both soil and mycorrhizal communities. The differences in arbuscular mycorrhizae communities of L. bullata are driven by a variety of factors including soil characteristics. Multivariate analysis shows that soil pH explains both 18S ribosomal RNA and Internal transcribed spacer community variance, and total nitrogen further explains 18S community variance. This shows how these soil characteristics influence fungal communities in association with L. bullata and may be drivers of fungal communities