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Blenheim soil (Typic Quartzipsamment) and Bernam soil (Typic Endoaquept) with low and high Ganoderma basal stem rot (BSR) incidence, respectively, were studied to determine the role of naturally-occurring microbiota in suppressing basal stem rot (BSR) disease in oil palm. These coastal soils were also compared against a typical soil for nursery use, the inland Bungor soil (Typic Kandiudults). For each soil type, half of the soils were sterilized by autoclaving, and the other half were non-sterilized. These soils were then used for the microbiome analysis, evaluation of disease incidences, and effect on plant growth. Soil microbial communities were profiled using 16S and 18S ribosomal RNA gene amplicon sequencing on the Illumina MiSeq. Polybag trials were conducted over a period of 20 weeks. Results showed that by eliminating or inactivating the indigenous microbial communities from BSR-suppressive Blenheim soil through sterilization, this increased BSR incidences (from 50 to 92%) and severity (from 28 to 78%), and affected plant growth (reduction of 35% leaf area, 11% height, and 19% bole’s girth). Soil microbiome analysis revealed that Acidobacteriota, Nitrospirota, Latesbaciterota, Nanoarchaeota, Entotheonellaeta, Zixibacteria, Candidatus Yanofskybacteria (Patescibacteria), MB-A2-108 (Actinobacteriota), Cnidaria and Acaulospora (Mucoromycota) were less prevalent in sterilized Blenheim soil compared to non-sterilized Blenheim soil. Relative abundance of the genus Ganoderma was also lower in BSR-suppressive Blenheim soil compared to sterilized Blenheim soil. In contrast, disease development and plant growth remained unaffected by sterilization of BSR-conducive Bernam and Bungor soils, suggesting that naturally-occurring microbiota in these two soils played minimal roles in contributing to conducive conditions for disease development. Relative abundance of Ganoderma was higher in BSR-conducive Bernam and Bungor soils as well, compared to BSR-suppressive Blenheim. Results from this study provides the first insights into the soil microbiota in BSR suppressive soils and their role in BSR disease progression and growth of oil palms.

Fungal surface hydrophobicity has many ecological functions and water contact angles measurement is a direct and simple approach for its characterization. The objective of this study was to evaluate if in-vitro growth conditions coupled with versatile image analysis allows for more accurate fungal contact angle measurements. Fungal cultures were grown on agar slide media and contact angles were measured utilizing a modified microscope and digital camera setup. Advanced imaging software was adopted for contact angle determination. Contact angles were observed in hydrophobic, hydrophilic and a newly created chronoamphiphilic class containing fungi taxa with changing surface hydrophobicity. Previous methods are unable to detect slight changes in hydrophobicity, which provide vital information of hydrophobicity expression patterns. Our method allows for easy and efficient characterization of hydrophobicity, minimizing disturbance to cultures and quantifying subtle variation in hydrophobicity.

A new species, Sphaerodes mycoparasitica (Ascomycetes, Melanosporales), was isolated from isolates of Fusarium avenaceum and Fusarium graminearum originating from wheat fields in Saskatchewan, and from Fusarium oxysporum originating from asparagus fields in Quebec, Canada. The species is characterized by a unique combination of ascospore size, shape (fusiform and triangular) and wall ornamentation (reticulate and smooth). Also, conidia are produced from simple phialides on the surface of ascoma peridial wall, on ascoma surrounding hyphae, and on irregularly branched conidiophores arising from hyphae. The closest relation of S. mycoparasitica is Sphaerodes quadrangularis, which has no detected anamorphic stage. The description of S. mycoparasitica, its phylogenetic position-based on DNA sequences of large subunit ribosomal RNA gene (LSU)-as well as a key for all known Sphaerodes species are provided.