L. Pereg Laboratory

Plant-microbe interactions

Molecular factors in the associations of the fungus Thielaviopsis basicola with plants, leading to Black Root Rot disease
(CRDC/CCC-CRC funded project with prospects for Honours/PhD funding.)

Clamydospores of Thielaviopsis basicola(photo by S. Al-Jaaidi)

Black root rot presents a substantial threat to crops, such as cotton, tobacco, pansy, red clover, carrots strawberries and cucumbers. The disease, caused by the fungal pathogen Thielaviopsis basicola, affects crops in Australia, especially in cooler areas and seasons. We are a group of scientists from UNE and other institutes working together to study different aspects of the fungal disease. We have made progress in the development of tools to study plant and fungal
proteins as well as in the genetic manipulation of the fungal pathogen.

2) Signal Transduction Systems involved in Azospirillum-plant interactions

Bacterial survival depends upon constant monitoring of surrounding conditions and rapid adjustment to environmental changes. Azospirillum, an important genus of soil bacteria, is used as a model in the study of plant growth promotion. In A. brasilense the response-regulatory protein FlcA controls cell differentiation from vegetative into cyst

Azospirillum brasilense on wheat root, site of lateral root emergence (photo by L. Pereg)

forms and attachment to plant roots in response to environmental stimuli. It is involved in controlling the production of arabinose, a component of the extra-cellular polysaccharide layer surrounding the cell. The protein FlcA belongs to a family of two-component transcriptional regulators involved in signal transduction.

The aim of the project is to study the effects of external and cellular signals on the expression and activity of FlcA and study the involvement of such factors in bacterial differentiation and in interactions with plants. Another aim is to study structural motives of the FlcA protein and their involvement
in the process of signal transduction.

Marine Microbiology

1) Microbial probiotics in the aquaculture industry

Bacterial diseases are a major limiting factor in developing cultivation systems of ornate spiny lobster (Panulirus ornatus). Opportunistic pathogens cause infections as early as at the larval stages. A study at AIMS, in collaboration with the lobster industry, is aimed at identifying potential patheons and biocontrol agents. At UNE, we look at finding probiotic bacterial species that may suppress the growth of the larval pathogen.

GFP-tagged pathogen cells in larval gastrointestinal tract
(photo by E. Goulden)

Molecular tools are in used in analysing the mechanisms involved in pathogen suppression by probiotic candidates.

2) Microbial distribution and microbial processes in the marine benthos and its relation to aquatic organism survival or diseases

Marine benthos includes any organisms and systems in the bottom of the sea. It may include corals, benthic algae, seagrasses, marine sediment and many organisms associating with these systems, such as benthic fish, crabs, shrimps, microorganisms, etc. Many microbial processes, such as the nitrogen cycle, are essential for survival of marine organisms, in particular in nutrient-poor systems.

Novel microbial diseases of reef-building corals have altered total abundance and species diversity in reef communities, causing serious environmental and heritage damages and affecting regional tourism industries. Associative microorganisms play vital role in the survival of some marine species. If
you are interested in any of such marine microbial associations, whether pathogenic or beneficial, you may contact me to discuss a suitable project.

Lily Pereg Research

Coral reef (Photo by L. Pereg)

Dr. Lily Pereg lily.pereg@une.edu.au (02) 6773 2708