Abeeha Khalil
Project Title: The Role of Plant Growth Promoting Hormones in Phytoplankton-Bacteria Interactions.
Supervisors: Prof. Justin Seymour and Dr. Jean-Baptiste Raina.
Contact Detail: Abeeha.Khalil@student.uts.edu.au
Project Background: Phytoplankton are essential to marine ecosystems and contribute up to 50% of marine primary productivity. They are vital in maintaining ecosystem functioning in the aquatic environment, so understanding environmental parameters that influence their growth is of utmost importance. In the natural environment, phytoplankton growth can be limited by various abiotic factors, including temperature, light, and nutrient availability. However, recent studies have suggested that interactions with other microorganisms, mainly heterotrophic bacteria, play integral roles in the health and fitness of phytoplankton. In many instances, interactions between phytoplankton and bacteria are a fundamental inter-species relationship in the marine environment. They are responsible for shaping ecosystem productivity by controlling nutrient cycling at the base of aquatic food webs. Often, relationships between these organisms occur due to intercellular reciprocal exchanges of metabolites that take place at the ocean’s microscale. These interactions may influence functions such as biogeochemical cycles, which can have global-scale consequences. One important category of chemicals exchanged within these interactions is plant growth-promoting hormones which are known to play vital roles in terrestrial systems and have also shown evidence of growth-promoting abilities in planktonic systems. Due to the pivotal role of phytoplankton in natural aquatic ecosystems, a growing interest in the metabolic interactions between phytoplankton and members of their microbiome has occurred. Until now, however, only a few studies exploring the intimate ecological interactions between phytoplankton and bacteria have revealed the potential importance of bacterial production of plant growth-promoting hormones.
Project Aims: My project aims to understand the importance of plant growth-promoting hormones, focusing on their influence on the interactions between the diatom Actinocyclus curvatus and putatively symbiotic bacteria. I aim to understand: i) the diversity of bacteria producing plant growth-promoting hormones and their impact on diatom growth, ii) the identity and nature of unknown hormone pathways, and iii) the ecological mechanisms that underpin the efficient transfer of plant growth-promoting hormones between the bacteria and its phytoplankton partner. This will provide us an understanding of the effects of plant growth-promoting hormones in complex phytoplankton-bacteria interactions, ultimately contributing to improving our understanding of the intimate ecological interactions between these organisms and a specific knowledge of the growth-promoting abilities bacteria possess through their production of hormones.