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Oral: Metagenomics and the Phytobiome


Unravelling the sugarcane microbiome to resolve the Yellow Canopy Syndrome in Australia
K. HAMONTS (1), P. Trivedi (2), A. Garg (2), P. Holford (3), J. Grinyer (2), I. Anderson (2), B. Singh (2) (1) Hawkesbury Institute for the Environment, Australia; (2) Hawkesbury Institute for the Environment, Western Sydney University, Australia; (3) Sch

Yellow Canopy Syndrome (YCS) is a largely undiagnosed condition impacting sugarcane crops in Queensland, Australia, causing yield losses up to 30%. Since the first observation of YCS near Cairns in 2012, the condition has spread to all major cane growing areas and is a critical issue for the industry. Key YCS symptoms differ from leaf yellowing due to drought stress, phytotoxicity, insect attack, known diseases, nutrient deficiency or natural maturing. Despite elimination of some potential causes, the causal agent of YCS remains unknown. We aim to determine the involvement of biotic interactions and soil nutritional health in YCS development. A microbiome-based approach using Illumina MiSeq and HiSeq was applied on 598 samples to reveal the complexity of organisms (bacteria, fungi, other eukaryotes, viruses) present in YCS-affected sugarcane and rhizosphere soil. Soil nutrient status and microbial enzyme activity were also determined and did not significantly differ between affected and healthy fields. Bacterial (>25000 OTUs) and fungal (>11000 OTUs) assemblages of leaves, stalks, roots and rhizosphere soils differed between asymptomatic vs. symptomatic plants, as well as some rhizosphere microbial functions. Community shifts with YCS appeared variety-specific, and to date few consistent bacterial and fungal and no viral signals associated with YCS emerged. We envision ongoing data mining may reveal potential causal agent(s) of YCS or management practices for YCS.