Rhytidhylides A and B, Two New Phthalide Derivatives from the Endophytic Fungus Rhytidhysteron sp. BZM-9.

Two new phthalide derivatives, rhytidhylides A (1) and B (2), together with ten known compounds (3-12) were isolated from cultures of Rhytidhysteron sp. BZM-9, an endophyte isolated from the leaves of Leptospermum brachyandrum. Their structures were identified by an extensive analysis of NMR, HRESIMS, ECD, and through comparison with data reported in the literature. In addition, the cytotoxic activities against two human hepatoma cell lines (HepG2 and SMMC7721) and antibacterial activities against MRSA and E. coli were evaluated.

A core phyllosphere microbiome exists across distant populations of a tree species indigenous to New Zealand.

The phyllosphere microbiome is increasingly recognised as an influential component of plant physiology, yet it remains unclear whether stable host-microbe associations generally exist in the phyllosphere. Leptospermum scoparium (manuka) is a tea tree indigenous to New Zealand, and honey derived from manuka is widely known to possess unique antimicrobial properties. However, the host physiological traits associated with these antimicrobial properties vary widely, and the specific cause of such variation has eluded scientists despite decades of research. Notably, the manuka phyllosphere microbiome remains uncharacterised, and its potential role in mediating host physiology has not been considered. Working within the prevailing core microbiome conceptual framework, we hypothesise that the phyllosphere microbiome of manuka exhibits specific host association patterns congruent with those of a microbial community under host selective pressure (null hypothesis: the manuka phyllosphere microbiome is recruited stochastically from the surrounding environment). To examine our hypothesis, we characterised the phyllosphere and associated soil microbiomes of five distinct and geographically distant manuka populations across the North Island of New Zealand. We identified a habitat-specific and relatively abundant core microbiome in the manuka phyllosphere, which was persistent across all samples. In contrast, non-core phyllosphere microorganisms exhibited significant variation across individual host trees and populations that was strongly driven by environmental and spatial factors. Our results demonstrate the existence of a dominant and ubiquitous core microbiome in the phyllosphere of manuka, supporting our hypothesis that phyllosphere microorganisms of manuka exhibit specific host association and potentially mediate physiological traits of this nationally and culturally treasured indigenous plant. In addition, our results illustrate biogeographical patterns in manuka phyllosphere microbiomes and offer insight into factors contributing to phyllosphere microbiome assembly.

Eutyscoparols A-G, polyketide derivatives from endophytic fungus Eutypella scoparia SCBG-8.

The chemical investigation on Eutypella scoparia SCBG-8, an endophytic fungus isolated from the leaves of Leptospermum brachyandrum, has resulted in the isolation of six new phenolic compounds eutyscoparols A-F (1-6) and one new natural product eutyscoparol G (7). The structures and absolute configurations of compounds 1-7 were determined by extensive chemical and spectroscopic analyses such as single crystal X-ray diffractions. Moreover, all compounds were evaluated for their antibacterial and cytotoxic activities in vitro.

Growth and survival of seedlings of native plants in an impoverished and highly disturbed soil following inoculation with arbuscular mycorrhizal fungi.

We investigated whether arbuscular mycorrhizas influenced growth and survival of seedlings in an extremely impoverished and highly disturbed soil. Seedlings of four plants species native to the site were either inoculated with native sporocarpic arbuscular mycorrhizal (AM) fungi or fertilised prior to transplanting, and followed over 86 weeks at the site. One treatment was also irrigated with N-rich leachate from the site. In a laboratory experiment, seedlings were fertilised with excess P for 6 weeks, and location of the P store determined. Growth and survival of AM and fertilised seedlings were similar at the site. Inoculated mycorrhizal fungi and roots appeared to extend into the surrounding soil together. P concentration in leaves of all plants was extremely low. Irrigation with leachate increased growth of seedlings. In the laboratory experiment, significantly more P was stored in roots than shoots. We suggest that successful revegetation of extremely disturbed and impoverished sites requires selection of mycorrhizal fungi and plants to suit the edaphic conditions and methods of out-planting.