Re ECF Project: 2014-03

Project Title: Rhizosphere Microbiome Analysis of Brown Root Rot Disease Infected Trees

Applicant: Prof KWAN Hoi Shan of The Chinese University of Hong Kong

Total Approved Grant: $ 482,475 (ECF & WWGF: 50/50)

Duration: 1/2/2015 to 30/9/2016

Project Status/Remarks: Completed

The proposed project aims to produce baseline datasets of the rhizosphere microbiome of Phellinus noxius infected trees in Hong Kong. Composition and diversity of the bacteria, archaea and microbial eukaryotes present in the rhizosphere of infected trees will be examined by the use of the Ion Torrent sequencing platform and compared to those recovered from the rhizospheres of healthy trees. An early infection detection system would be crucial for the early administration of treatment, and thereby increasing the survival rates of the trees. To achieve this goal, an in-depth understanding into the changes occurring in the microbiome in the rhizosphere of the diseased and healthy trees would be required to understand the progression of the disease and its effects on the surrounding environment for better conservation of agriculture as well as to uncover potential biomarkers for the presence of the disease.

Summary of the Findings/Outcomes:
This project provided a baseline study into the changes that occur to the rhizosphere microbiome in the presence of a Phellinus noxius infection. The rhizosphere microbiome is made up of a complex web of microorganisms, including bacteria, archaea and fungi, which interact with each other and with the host plant. The rhizosphere microbiome is an important area of research as it sheds insight into what biotic factors make plants susceptible to infections, which could in turn predict when a plant has succumbed to disease through the presence or absence of certain microorganisms. In this study, the research team revealed the diversity and composition of (i) bacterial, (ii) archeal and (iii) fungal communities in the rhizosphere of Phellinus noxius infected trees and healthy trees. It was shown that bacterial communities remained mostly unaffected when a tree had been infected with P. noxius. Higher levels of the common soil dwelling archaea NRPJ occurred in P. noxius infected samples (both in trees in the field in Hong Kong and artificially infected trees) compared to uninfected samples. The diversity and composition of the fungal community was affected under P. noxius infection. There were higher levels of pathogenic fungi present in infected samples which might be the result of secondary opportunistic infections.